WO1994016556A1 - Transgenic mammals - Google Patents

Transgenic mammals Download PDF

Info

Publication number
WO1994016556A1
WO1994016556A1 PCT/US1994/000526 US9400526W WO9416556A1 WO 1994016556 A1 WO1994016556 A1 WO 1994016556A1 US 9400526 W US9400526 W US 9400526W WO 9416556 A1 WO9416556 A1 WO 9416556A1
Authority
WO
WIPO (PCT)
Prior art keywords
promoter
mammal
megakaryocyte
platelet
nucleic acid
Prior art date
Application number
PCT/US1994/000526
Other languages
French (fr)
Inventor
Murray O. Robinson
Pamela Hunt
Robert A. Bosselman
Original Assignee
Amgen Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Amgen Inc. filed Critical Amgen Inc.
Priority to JP6517125A priority Critical patent/JPH08506014A/en
Priority to AU60888/94A priority patent/AU6088894A/en
Publication of WO1994016556A1 publication Critical patent/WO1994016556A1/en

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09Recombinant DNA-technology
    • C12N15/63Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
    • C12N15/79Vectors or expression systems specially adapted for eukaryotic hosts
    • C12N15/85Vectors or expression systems specially adapted for eukaryotic hosts for animal cells
    • C12N15/8509Vectors or expression systems specially adapted for eukaryotic hosts for animal cells for producing genetically modified animals, e.g. transgenic
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01KANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K67/00Rearing or breeding animals, not otherwise provided for; New breeds of animals
    • A01K67/027New breeds of vertebrates
    • A01K67/0275Genetically modified vertebrates, e.g. transgenic
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07KPEPTIDES
    • C07K14/00Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/005Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from viruses
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01KANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K2217/00Genetically modified animals
    • A01K2217/05Animals comprising random inserted nucleic acids (transgenic)
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01KANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K2227/00Animals characterised by species
    • A01K2227/10Mammal
    • A01K2227/105Murine
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01KANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K2267/00Animals characterised by purpose
    • A01K2267/03Animal model, e.g. for test or diseases
    • A01K2267/0331Animal model for proliferative diseases
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01KANIMAL HUSBANDRY; CARE OF BIRDS, FISHES, INSECTS; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K2267/00Animals characterised by purpose
    • A01K2267/03Animal model, e.g. for test or diseases
    • A01K2267/035Animal model for multifactorial diseases
    • A01K2267/0381Animal model for diseases of the hematopoietic system
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N2710/00MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA dsDNA viruses
    • C12N2710/00011Details
    • C12N2710/22011Polyomaviridae, e.g. polyoma, SV40, JC
    • C12N2710/22022New viral proteins or individual genes, new structural or functional aspects of known viral proteins or genes

Definitions

  • This invention relates to mammals into which foreign DNA has been introduced, thereby generating transgenic mammals. More specifically, the invention concerns generation of transgenic mammals that have a decreased platelet count, megakaryocyte leukemia, or both conditions.
  • transgenic mammals involves the insertion of novel nucleic acid sequences into one or more chromosomes of the mammal.
  • the DNA is typically delivered to the pronucleus of an egg where it is incorporated into the DNA of the embryo. This embryo is then implanted into a "surrogate host" for the duration of gestation. The offspring of the surrogate host are evaluated for the presence of the novel nucleic acid sequence (s) .
  • transgenic mammals are valuable for in vivo screening and testing of compounds that may be useful in treating or preventing the disease (s), and/or for developing methods useful in diagnosing the disease.
  • Transgenic mammals have been described in the art. Wagner et al . , U.S. Patent No. 4,873,191 teach mammals containing exogenous DNA which has been introduced by microinjection of the DNA into a mammalian zygote.
  • mice with a DNA construct that contains a mutant SV40 large T antigen gene (the SV40 tsA58 mutant) linked to a major histocompatibility complex I promoter (H-2Kb) .
  • the specific promoter is used to facilitate expression of the transgene in a wide variety of tissues, and is induced by certain interferons. These mice are used as a source for generating transformed cell lines.
  • mice With a construct containing the SV40 early region genes and a metallothionein fusion gene. Several of the mice developed choroid plexus tumors, and/or thymic hypertrophy.
  • Thrombocytopenia a decreased level of platelets in the blood relative to normal levels for a given mammalian species, affects the blood clotting ability of afflicted individuals.
  • One manifestation of this disorder is increased bleeding.
  • thrombocytopenia is a common side effect in patients receiving chemotherapy.
  • the only currently available method for treating the disorder is platelet transfusion, a difficult and inherently risky procedure.
  • Jackson, Blood Cells, 11:237-253 [1989] describes a rat strain with a reduced platelet number.
  • Megakaryocyte leukemia is a condition characterized by production of cancerous cells that have phenotypic traits resembling megakaryocytes. Such leukemia is currently treated by bone marrow transplants.
  • transgenic mammal that has a genotype which confers an increased proclivity towards thrombocytopenia and/or megakaryocyte leukemia as compared to a non- transgenic mammal.
  • Such mammals are useful in screening compounds for treating these diseases, and for other purposes.
  • mice containing a nucleic acid construct encoding the SV40 early region tsA58 mutant regulated by the rat PF4 promoter unexpectedly develop varying levels of thrombocytopenia and/or megakaryocyte leukemia.
  • the mice present a novel and useful system for screening compounds useful for treating and/or preventing these diseases.
  • a mammal containing a transgene and its progeny are provided.
  • a mouse containing a transgene and its progeny are provided.
  • a method of preparing a mammal with a decreased platelet level as compared to normal platelet counts for that species of that mammal which comprises: (a) introducing into a fertilized embryo a vector comprising nucleic acid encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor or megakaryocyte promoter; and
  • the offspring can be screened for decreased platelet counts.
  • a method of preparing mammals exhibiting megakaryocyte leukemia which comprises:
  • cell lines derived from certain tissues of the transgenic mammals such as bone marrow, lymph node and spleen are provided.
  • Figure 1 is a diagramatic representation of the DNA construct integrated into the genome of transgenic mice.
  • the sequence comprises about 1.1 kb of the Sprague-Dawley rat PF4 promoter sequence linked to the early region of the tsA58 mutation of SV40 viral genome.
  • Figure 2 depicts the nucleic acid sequence of a Sprague-Dawley rat PF4 promoter as originally sequenced(SE ⁇ ) ID NO:l) .
  • Figure 3A depicts platelet counts of founder transgenic mice.
  • Figure 3B shows platelet counts of F2 mice hemizygous or homozygous for the transgene.
  • Figure 3C shows acetylcholinesterase activity (a marker for megakaryocytes) versus platelet count in Fl mice.
  • Figure 4 depicts a comparison of the Fisher rat (bottom sequence) and Sprague-Dawley rat (top sequence) PF4 promoter sequences. The sequences have been aligned in a manner to maximize their homology. The nucleic acid sequence differences are indicated.
  • the term "vector” refers to nucleic acid sequence, arranged in such an order and containing appropriate components such that they are taken up into cells or can be inserted into cells through microinjection or other techniques. Such sequences may or may not naturally be present in the cell, either in whole or in part.
  • the vector contains a promoter or promoters, a structural gene of interest that is to be transferred and expressed in the cell or organism (host) transfected with the vector, and other elements necessary for gene transfer and/or expression in the host such as sequences enabling the processing and translation of the transcription seuences, including translation initiation and polyadenylation sequences.
  • the vector used may be circular or linear, and is preferably linear for insertion into embryos to generate a transgenic mammal.
  • promoter refers to a nucleic acid sequence that regulates the transcription of its corresponding nucleic acid coding sequence or structural gene.
  • the term “promoter” in the context of the present invention may include enhancer, repressor, transcription initiation site(s) and other such elements involved in the overall functioning of the promoter in regulating transcription of the corresponding structural gene.
  • Preferred promoters of this invention include those promoters primarily active in platelet precursor cells, megakaryocytes, and/or megakaryocyte precursor cells such as, for example, the PF4 promoter (Ravid et al . , 1992, supra) , and the MPL promoter (Wendling et al . , Blood :246a [1992]).
  • operably linked refers to the orientation of the promoter with respect to the structural gene(s) of interest along the vector.
  • the promoter is placed in such a position that it is capable of controlling or regulating the expression of the structural gene(s).
  • platelet precursor promoter and “megakaryocyte promoter” refer to promoters that are active, (i.e., capable of driving expression of the structural genes to which they are operably linked) , primarily in platelet precursor cells and/or megakaryocytes and megakaryocyte progenitor cells. Such promoters may exhibit minimal acitivity in other tissues or cell types.
  • transgene refers to a gene that is
  • mutant form is meant a gene that contains one or more nucleotides in the gene sequence that are different from, i . e . , substitutes for, the wild-type or natural sequence; alternatively, or additionally, the gene may contain nucleotide insertions or deletions.
  • SV40 tsA58 early region refers to the nucleic acid encoding the simian virus early region genes, where the large T antigen encoded in the early region nucleic acid sequence contains a mutation, the tsA58 mutation, resulting in an altered activity as compared to the naturally occurring, wild-type large T antigen gene, as described by Tegtmeyer, J. Virol . , 11:613-618 [1975] .
  • mice refers to all non-human animals that belong to the class mammalia.
  • the term includes all members of the class mammalia except humans.
  • the term includes all strains of rodents such as rabbits, rats, mice, and hamsters.
  • rats, hamsters and mice are especially preferred for use in the invention.
  • mice especially those strains that provide high nuclear yield, good pronuclear visibility, good in vitro viability, and good reproductive fitness in the adult, i . e . , those considered to be healthy.
  • progeny and “progeny of the transgenic mammal” refer to any and all offspring of every generation subsequent to the originally transformed mammals.
  • thrombocytopenia refers to a decreased platelet count in the blood relative to a normal platelet count. Such a decrease is meant herein to include any level below that determined as normal for the particular mammalian species of interest . Thrombocytopenia may appear at any stage of the mammal's development, and may be temporary or permanent. Where temporary, the disease may reappear at any time in the lifecycle of the mammal. Thrombocytopenia may or may not be inherited by the offspring of those mammals affected with it.
  • megakaryocyte leukemia and “megakaryocytic leukemia” describe a condition wherein a cell or cells of the mammal divide in an uncontrolled manner, resulting in a pathological state.
  • Such cells express markers of the megakaryocyte lineage including, without limitation, the markers designated as platelet factor 4, von Willebrand factor, and other proteins immunoreactive with antisera produced against platelets.
  • platelet factor 4 the markers designated as platelet factor 4, von Willebrand factor, and other proteins immunoreactive with antisera produced against platelets.
  • such cells may be morphologically identifiable as megakaryocytes using standard criteria to identify such cells.
  • mammalian cell line refers to cells derived from tissues or tumors of mammals that are able to survive and/or divide under appropriate culture conditions. As used herein, this term includes all successive generations of the cells originally derived from tissues or tumors.
  • the term "fertilized mammalian embryo” refers to the early zygote, especialy a single cell, resulting from the fusion of an oocyte and a sperm.
  • the terms "surrogate host” and “surrogate mother” may be used interchangably, and refer to a mammal, preferably a female, that is implanted with a fertilized embryo into which transgene (s) have been introduced.
  • the surrogate host is typically of the same or a similar species as the embryo, and is receptive to the embryos by appropriate treatment with hormones where necessary and/or copulation with a vasectomized male.
  • test tube As used herein, however, the terms are meant to include also a test tube, dish, and/or incubator or other suitable instrument that may be used as a receptacle for embryo maturation and development, either as a substitute for, or in addition to implantation of the embryo into a mammal of the same or similar species.
  • the transgene of interest is selected for its ability to affect cell cycle control and regulation, and/or its ability to promote growth and/or division of cells .
  • the simultaneous use of more than one transgene for insertion into a single embryo is within the scope of this invention.
  • a gene(s) that alters platelet levels in the mammal into which it is introduced, and/or in the offspring of such mammals is the preferred transgene (s) herein.
  • the structural gene may be obtained from any source, including viral, unicellular prokaryotic or eukaryotic organisms, vertebrate or non- vertebrate mammals, or plants. If obtained from vertebrate mammals, the structural gene may be from a homologous source (i . e .
  • transgene may have additional effects on the phenotype of the transgenic mammal, and these effects may be related or unrelated to platelet levels.
  • Preferred transgenes for use in the present invention include myc, myb, E2F (Nevins, J.R., Science 211:424-429 [1992]), abl ras. pim.l.
  • src E1A (Nevins, supra) , HPVE7 (human papilloma virus E7, Nevins, supra) , and SV40 early region, SV40 large T antigen, SV40 large T antigen tsA58 mutant, and mutants and fragments thereof.
  • More preferred genes include myc, E2F, SV40 early region, and the SV40 early region tsA58 mutant. The most preferred gene is SV40 early region tsA58 mutant.
  • Promoters useful in practicing this invention are those that are highly regulated with respect to activity, both temporally and spacially.
  • the promoters of choice are those that are active only in particular tissues or cell types, preferably platelets, platelet precursor cells, and/or megakaryocytes.
  • the source of the promoter may be from any unicellular prokaryotic or eukaryotic organism, any vertebrate or invertebrate, or any plant. Where the promoter is obtained from a mammal, the mammal may be homologous (the same species as the mammal to be transfected) or non-homologous (a different species) .
  • Preferred promoters of this invention are those expressed primarily in platelets and platelet precursors such as megakaryocytes.
  • Preferred for use in the present invention are the PF4 promoter, the alpha-IIB integrin promoter (Marguerie et ai., 7th International Symposium on the Biology of Vascular Cells, p. 18, San Diego,
  • the glycoprotein GPIb promoter (Uzan et al . , J. Biol . Chem. , 211:8932-8939 [1991]), the platelet glycoprotein GPIIb promoter (Wenger et al . , Biochem. Biophys . Res . Comm. , 111:389-395 [1988]), the promoter of the M2PTP gene (Plutzsky et al . , Proc. Nat 'l . Acad. Sci . USA, 12:1123-1127 [1992]) and the MPL promoter
  • the vectors of this invention preferably contain other elements useful for optimal functioning of the vector in the mammal into which the vector is inserted. These elements are well known to those of ordinary skill in the art, and are described, for example in Sambrook et al . , Cold Spring Harbor Laboratory Press, 1989.
  • Vectors used for transforming mammalian embryos are constructed using methods well known in the art, including, without limitation, the standard techniques of restriction endonuclease digestion, ligation, plasmid and DNA and RNA purification, DNA sequencing, and the like as described, for example in Sambrook, Fritsch, and Maniatis, eds., Molecular Cloning: A Laboratory Manual . , (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY [1989]).
  • a preferred vector for use in the invention is plasmid 4C, illustrated in Figure 1, and deposited in the ATCC, as noted below.
  • the specific lines of any mammalian species used to practice this invention are selected for general good health, good embryo yields, good pronuclear visibility in the embryos, and good reproductive fitness.
  • lines such as C57/BL6 x DBA2 Fl cross, or FVB lines are used (obtained commercially from Charles River Labs) .
  • the age of the mammals that are used to obtain embryos and to serve as surrogate hosts is a function of the species used, but is readily determined by one of ordinary skill in the art. For example, when mice are used, pre-puberal females are preferred, as they yield more embryos and respond better to hormone injections.
  • the male mammal to be used as a stud will normally be selected by age of sexual maturity, among other criteria.
  • hormones or other chemical compounds may be necessary to prepare the female for egg production, mating, and/or reimplantation of embryos.
  • the type of hormones/cofactors and the quantity used, as well as the timing of administration of the hormones will vary for each species of mammal. Such considerations will be readily apparent to one of ordinary skill in the art
  • a primed female i.e., one that is producing eggs that can be fertilized
  • a stud male i.e., one that is producing eggs that can be fertilized
  • the resulting fertilized embryos are then removed for introduction of the transgene (s) .
  • eggs and sperm may be obtained from suitable females and males and used for in vitro fertilization to produce an embryo suitable for introduction of the transgene.
  • fertilized embryos are incubated in suitable media until the pronuclei appear.
  • exogenous nucleic acid comprising the transgene of interest is introduced into the female or male pronucleus.
  • the male pronucleus is preferred.
  • nucleic acid may be accomplished by any means known in the art such as, for example, microinjection. Following introduction of the nucleic acid into the embryo, the embryo may be incubated in vitro for varying amounts of time, or reimplanted into the surrogate host, or both. In vitro incubation to maturity is within the scope of this invention. One common method is to incubate the embryos in vitro for 1-7 days and then reimplant them into the surrogate host.
  • Reimplantation is accomplished using standard methods. Usually, the surrogate host is anesthetized, and the embryos are inserted into the oviduct. The number of embryos implanted into a particular host will vary, but will usually be comparable to the number of offspring the species naturally produces.
  • Transgenic offspring of the surrogate host may be screened for the presence of the transgene by any suitable method. Screening is often accomplished by Southern or Northern analysis, using a probe that is complementary to at least a portion of the transgene. Western blot analysis using an antibody against the protein encoded by the transgene may be employed as an alternative or additional method for screening.
  • the tissues or cells believed to express the transgene at the highest levels are tested, although any tissues or cell types may be used for this analysis.
  • Progeny of the transgenic mammals may be obtained by mating the transgenic mammal with a suitable partner, or by in vitro fertilization of eggs and/or sperm obtained from the transgenic mammal. Where in vitro fertilization is used, the fertilized embryo may be implanted into a surrogate host or incubated in vitro, or both. Where mating is used to produce transgenic progeny, the transgenic mammal may be backcrossed to a parental line. Using either method, the progeny may be evaluated for the presence of the transgene using methods described above, or other appropriate methods.
  • the transformed mammals, their progeny, and cell lines of the present invention provide several important uses that will be readily apparent to one of ordinary skill in the art.
  • the mammals and cell lines are particularly useful in screening compounds that have potential as prophylactic or therapeutic treatments for thrombocytopenia and/or megakaryocyte leukemia.
  • screening of candidate compounds is conducted by administering the compound(s) to be tested to the mammal, over a range of doses, and evaluating the mammal's physiological reponse to the compound(s) over time.
  • Administration may be oral, or by suitable injection, depending on the chemical nature of the compound being evaluated. In some cases, it may be appropriate to administer the compound in conjunction with co-factors that would enhance the efficacy of the compound.
  • the compound is added to the cell culture medium at the appropriate time, and the cellular response to the compound is evaluated over time using the appropriate biochemical and/or histological assays
  • the compound of interest may be applied to the culture medium in conjunction with co-factors that would enhance the efficacy of the compound.
  • This fragment was cloned into the vector pBluescript II KS+ (Stratagene, La Jolla, CA) by digesting the pBluescript vector with the restriction endonuclease EcoRV and ligating the insert and the vector with DNA ligase. The resulting clones were isolated and transformed into E . coli DH5 ⁇ cells for plasmid amplification. Plasmid was purified from the cells using the standard alkaline lysis method. This clone was designated plasmid "4A". More than 20 differences between the published sequence from Fisher rat (Ravid et al . [1991], supra) and the sequenced clone were identified. These differences are identified in Figure 4.
  • a DNA fragment generated by Kpnl and BamHI restriction enzyme digestion containing the wild-type SV40 virus early region was ligated into the pBluescript II KS+ vector previously digested with the restriction endonucleases Kpnl and BamHI.
  • This ligated vector containing the SV40 insert was then digested with Hpal, removing a DNA fragment of -1.1 kb from position 3733 to 2666 of the SV40 early region.
  • the same fragment from an SV40 clone containing the tsA58 mutation (Alanine to Valine at position 3505) described by Tegtmeyer, supra, was ligated into the vector.
  • the resulting vector was transformed into E. coli DH5 ⁇ cells for plasmid amplification.
  • the desired plasmid was isolated from these cells and was designated plasmid "4B".
  • Plasmid 4C is deposited at the ATCC in transformed E. coli DH5 ⁇ cells and is available under the accession number ATCC 69182.
  • PMS Pregnant mare's serum
  • FSH Follicle Stimulating Hormone
  • the embryos were teased out of the oviduct and allowed to settle at the bottom of the slide as the cumulus cells detached from the embryos.
  • the cumulus masses were disaggregated (about 5 minutes) the embryos were transferred through two washes of M2 medium and the fertilized embryos were separated from unfertilized and abnormal embryos.
  • the fertilized embryos were then transferred through 5% CO2 equilibrated M16 medium (Hogan et al . , supra) , placed in equilibrated microdrop dishes containing Ml6 medium under paraffin oil and returned to the incubator.
  • Fertilized embryos were selected in Ml6 medium and incubated about 5 hours at 37°C until the pronuclei appeared. Embryos were then transferred into M2 medium in a shallow depression slide under paraffin oil and placed under the microscope. The pronuclei were easily visible under 200X magnification. Using suction on the holding pipet, a single embryo was selected and rotated such that the male pronucleus was away from the holding pipet. Approximately 200 picoliter of solution containing the DNA construct at about 1 microgram per ml was injected into the one of the pronuclei, preferably the male pronucleus.
  • Reimplantations were performed on anaesthetized mice of strain C57/BL6 x DBA2 Fl cross using a dissecting microscope.
  • a pseudo-pregnant female mouse was anaesthetized with 0.017-0.020 ml/g body weight of avertin, injected IP.
  • the mouse was placed under the dissecting microscope and the incision area was disinfected with 70% ethanol.
  • the ovary was exteriorized and the bursal sac that surrounds the ovary and the oviduct was carefully pulled open. The ovary and oviduct were separated to expose the opening of the oviduct (termed the infindibulum) . Surviving embryos were then removed from the incubator and loaded into the reimplantation pipet.
  • the tip of the pipet was inserted several millimeters into the infindibulum and gentle pressure was used to deliver the embryos into the oviduct. About 10 to 20 embryos were implanted per mouse, resulting in a litter size of 5 to 12. The ovary then was returned to the peritoneum, and the body wall and then the skin were sutured.
  • transgenic mice 20 contained the transgene as assayed by specific PCR amplification using the oligonucleotides described in Section A above. These results were confirmed by Southern analysis (Sambrook et al . , [1989]) using a DNA probe generated from the oligonucleotides used for PCR analysis. These transgenic mice are termed the founder mice. Two of these mice died unexpectedly after tail biopsies, having bled profusely. The remaining 18 mice were bled by tail vein nick and the blood samples were placed into a tube containing EDTA powder. H. Analysis of Blood Cell Content
  • Blood cell content of each transgenic founder mouse was analyzed using a Sysmex TM Cell analyzer (TOA Medical Electronics, Kobe, Japan) . Twenty microliters of blood obtained from each mouse was added to manufacturer's diluent for analysis. Platelet counts, white blood cell counts, red blood cell counts, and mean platelet volume were all obtained on that instrument. All blood cell parameters were within the range observed for the control (nontransgenic) littermate mice, except for the platelet counts. Normal platelet counts for mice are 800,000-1,200,000 cells per microliter of blood. Platelet counts of the transgenic mice are shown in Figure 3A.
  • mice PS14, PS27, PS77, PS81, and PS102 had platelet levels that were 5-25% of the controls; founder mice PS2, PS7, PS64, PS71, and PS95 had platelet levels that were 25-60% of the controls; and mice PS22, PS24, PS25, PS28, PS29, PS32, PS43, and PS61 had platelet levels that were comparable to the levels of the control mice.
  • the majority of the transgenic mice had thrombocytopenia.
  • both hemizygous and homozygous Fl generation transgenic mice were derived from all lines except PS28, PS43, and PS61.
  • the Fl generation was prepared by backcrossing each line to the C57/BL6 xDBA2 Fl cross mouse line.
  • RNA/DNA hybridization assay (Hunt et al . , Blood 11 904-911 [1992]) was performed on DNA obtained from tail tissue of each mouse. This assay used both SV40 T antigen and mouse stem cell factor (SCF) RNA probes. The ratio between the T antigen signal and the SCF signal was used to determine the zygosity of the mice. Blood analysis was obtained for each mouse using the Sysmex TM system as described above. To assay the level of megakaryocytes in the transgenic Fl population, bone marrow cells were obtained from lines PS2, PS7, PS14, PS22, PS25, PS29, PS32, and PS77.
  • SCF mouse stem cell factor
  • the bone marrow cells were obtained by flushing marrow from the longbones of the hind legs using Levine's CATCH buffer (Levine, A. and Fedorko, M. J. Cell Biol . , 11:159 [1976]). These cells were stained for acetylcholinesterase, a marker for megakaryocytes (Burstein et al., J. Cell . Physiol . , 122:159-165 [1985]) and with May-Gruenwald Giesma stain. The results are shown in Figure 3C. As is apparent, there is a trend towards an inverse correlation between platelet count in the blood and megakaryocyte cell count in the bone marrow.
  • mice were dispersed and stained for acetylcholinesterase activity, and line PS14 was observed to contain about four times the number of acetylcholinesterase positive staining cells as observed in the control mice.
  • mice homozygous for the transgene were identified for lines PS2, PS7, PS22, and PS29. Platelet counts were obtained for these mice. The platelet counts are shown in Figure 3B where the solid boxes indicate hemizygosity for the transgene, and hatched boxes indicate homozygosity for the transgene. With the exception of line PS22, the homozygous mice exhibited a more severe platelet defciency phenotype than did the hemizygous mice.
  • Tissues from the PS22 line founder mouse were fixed and sectioned, and the presence of leukemic cells was observed in liver, intestine, and spleen; many of the cells tested stained positive with a polyclonal antibody directed against mouse platelets, and the nuclei of the leukemic cells were immunoreactive for an antibody to SV40 T antigen.
  • mice of lines PS14, PS24, and PS71 died before eight months of age. Necropsy of these animals revealed grossly enlarged spleens and mottled livers, suggesting a leukemic pathology.
  • Transgenic mice are examined for a moribund appearance, indicating imminent death.
  • the mice are euthanized and the spleen, bone marrow, and lymph node tissues are removed.
  • the tissues are immediately dispersed into suitable media such as RPMI 1640 containing a serum supplement such as fetal calf serum at 5-25% (v/v) , and appropriate growth factors including, without limitation, interleukin 3 and/or stem cell factor at appropriate levels.
  • suitable media such as RPMI 1640 containing a serum supplement such as fetal calf serum at 5-25% (v/v) , and appropriate growth factors including, without limitation, interleukin 3 and/or stem cell factor at appropriate levels.
  • Incubation of the cells is at 33°C, 37°C or 39°C.
  • the culture medium is changed regularly. After suitable time has elapsed for the cells to separate, the cells are assayed for the presence of megakaryocyte and/or platelet markers such as acetylcholineste
  • PF4 promoter linked to SV40 early region tsA58 mutant was deposited in E. coli host cells, under the terms of the Budapest Treaty, with DH5 ⁇ the American Type Culture
  • ATCC American Type Culture Collection
  • TTCAGTTCCC TAAAGGCATA GGGATTCTGA CATGTTTTGC AGTAGCCGTT 300
  • CTGTGGATCA CTTCCTCATC CCCTATCCCG GGTTTCCGGA CTGGGCTGGC 1150
  • TAGAGCCCCA GACCCCAGTT TCCCCGAGGT AGCCCTTGGA TATCAAGCTT 1250

Abstract

Transgenic mice and methods of preparing such mice are disclosed. The mice exhibit decreased platelet counts and/or megakaryocyte leukemia.

Description

TRA SGENIC MAMMALS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to mammals into which foreign DNA has been introduced, thereby generating transgenic mammals. More specifically, the invention concerns generation of transgenic mammals that have a decreased platelet count, megakaryocyte leukemia, or both conditions.
Description of Related Art
Production of transgenic mammals involves the insertion of novel nucleic acid sequences into one or more chromosomes of the mammal. The DNA is typically delivered to the pronucleus of an egg where it is incorporated into the DNA of the embryo. This embryo is then implanted into a "surrogate host" for the duration of gestation. The offspring of the surrogate host are evaluated for the presence of the novel nucleic acid sequence (s) .
Expression of the novel DNA sequence (s), or transgene (s) , can confer a new phenotype on the mammal. Depending upon the nucleic acid sequence (s) inserted and the level of expression in the mammal, the mammal may become more or less susceptible to a particular disease or series of diseases. Such transgenic mammals are valuable for in vivo screening and testing of compounds that may be useful in treating or preventing the disease (s), and/or for developing methods useful in diagnosing the disease.
Transgenic mammals have been described in the art. Wagner et al . , U.S. Patent No. 4,873,191 teach mammals containing exogenous DNA which has been introduced by microinjection of the DNA into a mammalian zygote.
Leder et al . , U.S. Patent No. 4,736,866, teach a transgenic mammal whose germ and somatic cells contain an activated oncogene sequence introduced into the mammal, or its ancestors, early in development (the one- cell or fertilized embryo stage) . Such transformation results in the animal having a greater than normal chance of developing neoplasms. Evans et al . , U.S. Patent No. 4,870,009, teach production of certain mammalian hormones by insertion of a DNA construct into fertilized mammalian eggs and implanting the fertilized eggs into a host mother for gestation. The DNA construct comprises a mammalian metallothionein gene promoter sequence fused to the mammalian hormone sequence of interest. The blood of the transformed mammals then is collected and the hormone of interest is isolated.
Noble et al . , WO 91/13150, published September 5, 1991, and Jat et al . , Proc . Nat 'l . Acad. Sci . USA,
££:5096-5100 [1991], teach production of mice with a DNA construct that contains a mutant SV40 large T antigen gene (the SV40 tsA58 mutant) linked to a major histocompatibility complex I promoter (H-2Kb) . The specific promoter is used to facilitate expression of the transgene in a wide variety of tissues, and is induced by certain interferons. These mice are used as a source for generating transformed cell lines.
Leder et al . , U.S. Patent No. 5,175,383, describe a male transgenic mouse expressing the int-2 gene in urogenital tissues resulting in benign prostatic hyperplasia or hypertrophy.
Krimpenfort et al . , U.S. Patent No. 5,175,384, describe a transgenic mouse with a decreased level of mature T-cells. Wagner et al . , U.S. Patent No. 5,175,385, describe a transgenic mouse expressing the human beta- interferon gene.
Ravid et al . , Proc . Nat 'l . Acad. Sci . USA- US.:1521-1525 [1991], discuss mice containing a transgene construct containing the platelet factor 4 promoter ("PF4") linked to the beta-galactosidase gene, and Ravid et al . , Mol . Cell Biol . , 11:6116-6127 [1991], teach various domains of the PF4 promoter. Palmiter et al . , Nature 116.:457-460 [1985], teach the formation of choroid plexus tumors in mice that contain the DΝA sequence for the 72 base-pair repeat SV40 enhancer and large-T antigen. When the SV40 enhancer element is not included in the DΝA construct, other pathologies are observed as well.
Brinster et al . , Cell 12:367-79 [1984], teach production of mice with a construct containing the SV40 early region genes and a metallothionein fusion gene. Several of the mice developed choroid plexus tumors, and/or thymic hypertrophy.
Thrombocytopenia, a decreased level of platelets in the blood relative to normal levels for a given mammalian species, affects the blood clotting ability of afflicted individuals. One manifestation of this disorder is increased bleeding. In addition, thrombocytopenia is a common side effect in patients receiving chemotherapy. The only currently available method for treating the disorder is platelet transfusion, a difficult and inherently risky procedure. Jackson, Blood Cells, 11:237-253 [1989] describes a rat strain with a reduced platelet number.
Peters et al . , Blood, 2£:745-754 [1990] describe an autosomal recessive mutation in mice that confers combined anemia and thrombocytopenia on afflicted mice. Megakaryocyte leukemia is a condition characterized by production of cancerous cells that have phenotypic traits resembling megakaryocytes. Such leukemia is currently treated by bone marrow transplants.
In view of the devastating effects of thrombocytopenia and megakaryocyte leukemia, there is a need in the art for suitable animals that provide in vivo model systems for studying the diseases and compounds that can be used to treat and/or prevent the diseases.
Accordingly, it is an object of the invention to provide a transgenic mammal that has a genotype which confers an increased proclivity towards thrombocytopenia and/or megakaryocyte leukemia as compared to a non- transgenic mammal. Such mammals are useful in screening compounds for treating these diseases, and for other purposes.
It is a further object herein to provide methods for preparing, and to prepare transgenic mammals containing such genotypes.
Other such objects will readily be apparent to one of ordinary skill in the art.
SUMMARY OF THE INVENTION
This invention is based on the unexpected discovery that transgenic mice containing a nucleic acid construct encoding the SV40 early region tsA58 mutant regulated by the rat PF4 promoter unexpectedly develop varying levels of thrombocytopenia and/or megakaryocyte leukemia. In accordance with this invention, the mice present a novel and useful system for screening compounds useful for treating and/or preventing these diseases. In one preferred embodiment of the invention, a mammal containing a transgene and its progeny are provided.
In another preferred embodiment, a mouse containing a transgene and its progeny are provided.
In still another preferred embodiment, there is provided a method of preparing a mammal with a decreased platelet level as compared to normal platelet counts for that species of that mammal which comprises: (a) introducing into a fertilized embryo a vector comprising nucleic acid encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor or megakaryocyte promoter; and
(b) implanting the transformed embryo in a surrogate host. In an additional aspect of this embodiment of the invention, the offspring can be screened for decreased platelet counts.
In yet another preferred embodiment, there is provided a method of preparing mammals exhibiting megakaryocyte leukemia which comprises:
(a) introducing into an embryo a vector comprising a nucleic acid sequence encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor or megakaryocyte promoter; and, (b) implanting the transformed embryo into a surrogate host. The offspring can be screened for megakaryoctye leukemia.
In other preferred embodiments, cell lines derived from certain tissues of the transgenic mammals such as bone marrow, lymph node and spleen are provided. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a diagramatic representation of the DNA construct integrated into the genome of transgenic mice. The sequence comprises about 1.1 kb of the Sprague-Dawley rat PF4 promoter sequence linked to the early region of the tsA58 mutation of SV40 viral genome.
Figure 2 depicts the nucleic acid sequence of a Sprague-Dawley rat PF4 promoter as originally sequenced(SEζ) ID NO:l) .
Figure 3A depicts platelet counts of founder transgenic mice. Figure 3B shows platelet counts of F2 mice hemizygous or homozygous for the transgene. Figure 3C shows acetylcholinesterase activity (a marker for megakaryocytes) versus platelet count in Fl mice.
Figure 4 depicts a comparison of the Fisher rat (bottom sequence) and Sprague-Dawley rat (top sequence) PF4 promoter sequences. The sequences have been aligned in a manner to maximize their homology. The nucleic acid sequence differences are indicated.
DETAILED DESCRIPTION OF THE INVENTION
The following terms, as defined below, are used to describe the invention:
As used herein, the term "vector" refers to nucleic acid sequence, arranged in such an order and containing appropriate components such that they are taken up into cells or can be inserted into cells through microinjection or other techniques. Such sequences may or may not naturally be present in the cell, either in whole or in part. Typically, the vector contains a promoter or promoters, a structural gene of interest that is to be transferred and expressed in the cell or organism (host) transfected with the vector, and other elements necessary for gene transfer and/or expression in the host such as sequences enabling the processing and translation of the transcription seuences, including translation initiation and polyadenylation sequences. In the present invention, the vector used may be circular or linear, and is preferably linear for insertion into embryos to generate a transgenic mammal.
As used herein, the term "promoter" refers to a nucleic acid sequence that regulates the transcription of its corresponding nucleic acid coding sequence or structural gene. The term "promoter" in the context of the present invention may include enhancer, repressor, transcription initiation site(s) and other such elements involved in the overall functioning of the promoter in regulating transcription of the corresponding structural gene. Preferred promoters of this invention include those promoters primarily active in platelet precursor cells, megakaryocytes, and/or megakaryocyte precursor cells such as, for example, the PF4 promoter (Ravid et al . , 1992, supra) , and the MPL promoter (Wendling et al . , Blood :246a [1992]).
As used herein, the term "operably linked" refers to the orientation of the promoter with respect to the structural gene(s) of interest along the vector. The promoter is placed in such a position that it is capable of controlling or regulating the expression of the structural gene(s).
The terms "platelet precursor promoter" and "megakaryocyte promoter" refer to promoters that are active, (i.e., capable of driving expression of the structural genes to which they are operably linked) , primarily in platelet precursor cells and/or megakaryocytes and megakaryocyte progenitor cells. Such promoters may exhibit minimal acitivity in other tissues or cell types. The term "transgene" refers to a gene that is
(1) either not naturally found in the mammal to be genetically manipulated; (2) is a mutant form of a gene naturally found in the mammal; (3) is a gene that serves to add additional copies of the same or a similar gene that is found in the mammal; (4) is a gene directed to be expressed in an abnormal lineage of cells; or (5) is a silent endogenous gene whose expression is induced. By "mutant form" is meant a gene that contains one or more nucleotides in the gene sequence that are different from, i . e . , substitutes for, the wild-type or natural sequence; alternatively, or additionally, the gene may contain nucleotide insertions or deletions.
The terms "SV40 tsA58 early region", "SV 40 T antigen", and "tsA58 mutant" refer to the nucleic acid encoding the simian virus early region genes, where the large T antigen encoded in the early region nucleic acid sequence contains a mutation, the tsA58 mutation, resulting in an altered activity as compared to the naturally occurring, wild-type large T antigen gene, as described by Tegtmeyer, J. Virol . , 11:613-618 [1975] .
As used herein, these terms may be used interchangably to infer either the large T antigen sequence of the SV40 early region, or the entire early region sequence. The term "mammal" refers to all non-human animals that belong to the class mammalia. Preferably, the term includes all members of the class mammalia except humans. More preferably, the term includes all strains of rodents such as rabbits, rats, mice, and hamsters. Especially preferred for use in the invention are rats, hamsters and mice. Most preferred are mice, especially those strains that provide high nuclear yield, good pronuclear visibility, good in vitro viability, and good reproductive fitness in the adult, i . e . , those considered to be healthy.
The terms "progeny" and "progeny of the transgenic mammal" refer to any and all offspring of every generation subsequent to the originally transformed mammals.
The terms "founder line", "founder mice" and "founders" refer to those mammals that are the mature product of the embryos to which the transgene was added by microinjection or by other technique, i.e., those mammals that grew from the embryos into which DNA was inserted, and that were implanted into one or more surrogate hosts. The term "thrombocytopenia" refers to a decreased platelet count in the blood relative to a normal platelet count. Such a decrease is meant herein to include any level below that determined as normal for the particular mammalian species of interest . Thrombocytopenia may appear at any stage of the mammal's development, and may be temporary or permanent. Where temporary, the disease may reappear at any time in the lifecycle of the mammal. Thrombocytopenia may or may not be inherited by the offspring of those mammals affected with it.
The terms "megakaryocyte leukemia" and "megakaryocytic leukemia" describe a condition wherein a cell or cells of the mammal divide in an uncontrolled manner, resulting in a pathological state. Such cells express markers of the megakaryocyte lineage including, without limitation, the markers designated as platelet factor 4, von Willebrand factor, and other proteins immunoreactive with antisera produced against platelets. In addition, such cells may be morphologically identifiable as megakaryocytes using standard criteria to identify such cells. The term "mammalian cell line" refers to cells derived from tissues or tumors of mammals that are able to survive and/or divide under appropriate culture conditions. As used herein, this term includes all successive generations of the cells originally derived from tissues or tumors.
The term "fertilized mammalian embryo" refers to the early zygote, especialy a single cell, resulting from the fusion of an oocyte and a sperm. The terms "surrogate host" and "surrogate mother" may be used interchangably, and refer to a mammal, preferably a female, that is implanted with a fertilized embryo into which transgene (s) have been introduced. The surrogate host is typically of the same or a similar species as the embryo, and is receptive to the embryos by appropriate treatment with hormones where necessary and/or copulation with a vasectomized male. As used herein, however, the terms are meant to include also a test tube, dish, and/or incubator or other suitable instrument that may be used as a receptacle for embryo maturation and development, either as a substitute for, or in addition to implantation of the embryo into a mammal of the same or similar species.
A. Preparation of Constructs for Transformation
1. Selection of Transσene
The transgene of interest is selected for its ability to affect cell cycle control and regulation, and/or its ability to promote growth and/or division of cells . The simultaneous use of more than one transgene for insertion into a single embryo is within the scope of this invention. A gene(s) that alters platelet levels in the mammal into which it is introduced, and/or in the offspring of such mammals is the preferred transgene (s) herein. The structural gene may be obtained from any source, including viral, unicellular prokaryotic or eukaryotic organisms, vertebrate or non- vertebrate mammals, or plants. If obtained from vertebrate mammals, the structural gene may be from a homologous source (i . e . , a gene from one mouse implanted into another mouse) , or from a non-homologous source (i . e . , a structural gene from rabbit implanted into a mouse) . The transgene may have additional effects on the phenotype of the transgenic mammal, and these effects may be related or unrelated to platelet levels. Preferred transgenes for use in the present invention include myc, myb, E2F (Nevins, J.R., Science 211:424-429 [1992]), abl ras. pim.l. src, E1A (Nevins, supra) , HPVE7 (human papilloma virus E7, Nevins, supra) , and SV40 early region, SV40 large T antigen, SV40 large T antigen tsA58 mutant, and mutants and fragments thereof. More preferred genes include myc, E2F, SV40 early region, and the SV40 early region tsA58 mutant. The most preferred gene is SV40 early region tsA58 mutant.
2. Selection of Promoter
Promoters useful in practicing this invention are those that are highly regulated with respect to activity, both temporally and spacially. Thus, the promoters of choice are those that are active only in particular tissues or cell types, preferably platelets, platelet precursor cells, and/or megakaryocytes. The source of the promoter may be from any unicellular prokaryotic or eukaryotic organism, any vertebrate or invertebrate, or any plant. Where the promoter is obtained from a mammal, the mammal may be homologous (the same species as the mammal to be transfected) or non-homologous (a different species) . Preferred promoters of this invention are those expressed primarily in platelets and platelet precursors such as megakaryocytes. Preferred for use in the present invention are the PF4 promoter, the alpha-IIB integrin promoter (Marguerie et ai., 7th International Symposium on the Biology of Vascular Cells, p. 18, San Diego, CA
[1992]),the glycoprotein GPIb promoter (Uzan et al . , J. Biol . Chem. , 211:8932-8939 [1991]), the platelet glycoprotein GPIIb promoter (Wenger et al . , Biochem. Biophys . Res . Comm. , 111:389-395 [1988]), the promoter of the M2PTP gene (Plutzsky et al . , Proc. Nat 'l . Acad. Sci . USA, 12:1123-1127 [1992]) and the MPL promoter
(Wendling et al . , Blood, :246a [1992]), all of which may be obtained from any source. Most preferred is the rat PF4 promoter.
3. Qther Vector Components
In addition to a promoter and one or more structural genes, the vectors of this invention preferably contain other elements useful for optimal functioning of the vector in the mammal into which the vector is inserted. These elements are well known to those of ordinary skill in the art, and are described, for example in Sambrook et al . , Cold Spring Harbor Laboratory Press, 1989.
4. Construction of Vectors
Vectors used for transforming mammalian embryos are constructed using methods well known in the art, including, without limitation, the standard techniques of restriction endonuclease digestion, ligation, plasmid and DNA and RNA purification, DNA sequencing, and the like as described, for example in Sambrook, Fritsch, and Maniatis, eds., Molecular Cloning: A Laboratory Manual . , (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY [1989]).
A preferred vector for use in the invention is plasmid 4C, illustrated in Figure 1, and deposited in the ATCC, as noted below.
B. Production of Transgenic Mammals
The specific lines of any mammalian species used to practice this invention are selected for general good health, good embryo yields, good pronuclear visibility in the embryos, and good reproductive fitness. For example, when transgenic mice are to be produced, lines such as C57/BL6 x DBA2 Fl cross, or FVB lines are used (obtained commercially from Charles River Labs) .
The age of the mammals that are used to obtain embryos and to serve as surrogate hosts is a function of the species used, but is readily determined by one of ordinary skill in the art. For example, when mice are used, pre-puberal females are preferred, as they yield more embryos and respond better to hormone injections.
Similarly, the male mammal to be used as a stud will normally be selected by age of sexual maturity, among other criteria.
Administration of hormones or other chemical compounds may be necessary to prepare the female for egg production, mating, and/or reimplantation of embryos. The type of hormones/cofactors and the quantity used, as well as the timing of administration of the hormones will vary for each species of mammal. Such considerations will be readily apparent to one of ordinary skill in the art
Typically, a primed female (i.e., one that is producing eggs that can be fertilized) is mated with a stud male, and the resulting fertilized embryos are then removed for introduction of the transgene (s) . Alternatively, eggs and sperm may be obtained from suitable females and males and used for in vitro fertilization to produce an embryo suitable for introduction of the transgene.
Normally, fertilized embryos are incubated in suitable media until the pronuclei appear. At about this time, exogenous nucleic acid comprising the transgene of interest is introduced into the female or male pronucleus. In some species such as mice, the male pronucleus is preferred.
Introduction of nucleic acid may be accomplished by any means known in the art such as, for example, microinjection. Following introduction of the nucleic acid into the embryo, the embryo may be incubated in vitro for varying amounts of time, or reimplanted into the surrogate host, or both. In vitro incubation to maturity is within the scope of this invention. One common method is to incubate the embryos in vitro for 1-7 days and then reimplant them into the surrogate host.
Reimplantation is accomplished using standard methods. Usually, the surrogate host is anesthetized, and the embryos are inserted into the oviduct. The number of embryos implanted into a particular host will vary, but will usually be comparable to the number of offspring the species naturally produces.
Transgenic offspring of the surrogate host may be screened for the presence of the transgene by any suitable method. Screening is often accomplished by Southern or Northern analysis, using a probe that is complementary to at least a portion of the transgene. Western blot analysis using an antibody against the protein encoded by the transgene may be employed as an alternative or additional method for screening.
Typically, the tissues or cells believed to express the transgene at the highest levels are tested, although any tissues or cell types may be used for this analysis.
Alternative or additional methods for evaluating the presence of the transgene include, without limitation, suitable biochemical assays such as enzyme and/or immunological assays, histological stains for particular markers or enzyme activities, and the like. Blood count data is useful for evaluation of thrombocytopenia. Progeny of the transgenic mammals may be obtained by mating the transgenic mammal with a suitable partner, or by in vitro fertilization of eggs and/or sperm obtained from the transgenic mammal. Where in vitro fertilization is used, the fertilized embryo may be implanted into a surrogate host or incubated in vitro, or both. Where mating is used to produce transgenic progeny, the transgenic mammal may be backcrossed to a parental line. Using either method, the progeny may be evaluated for the presence of the transgene using methods described above, or other appropriate methods.
The transformed mammals, their progeny, and cell lines of the present invention provide several important uses that will be readily apparent to one of ordinary skill in the art. The mammals and cell lines are particularly useful in screening compounds that have potential as prophylactic or therapeutic treatments for thrombocytopenia and/or megakaryocyte leukemia.
In the case of transgenic mammals, screening of candidate compounds is conducted by administering the compound(s) to be tested to the mammal, over a range of doses, and evaluating the mammal's physiological reponse to the compound(s) over time. Administration may be oral, or by suitable injection, depending on the chemical nature of the compound being evaluated. In some cases, it may be appropriate to administer the compound in conjunction with co-factors that would enhance the efficacy of the compound.
In screening cell lines for compounds useful in treating thrombocytopenia and/or megakaryocytic leukemia, the compound is added to the cell culture medium at the appropriate time, and the cellular response to the compound is evaluated over time using the appropriate biochemical and/or histological assays
In some cases, it may be appropriate to apply the compound of interest to the culture medium in conjunction with co-factors that would enhance the efficacy of the compound.
The invention will be more fully understood by reference to the following examples. They should not be construed in any way as limiting the scope of the present invention.
EXAMPLES
A. Platelet Factor 4 (PF4) Promoter Cloning
An -1.1 kb fragment of the 5' region of the platelet factor 4 ("PF4") gene from a Sprague-Dawley genomic DNA library was cloned by polymerase chain reaction (PCR) amplification using the complimentary oligonucleotides (SEQ ID No: 2) GCTTGAATTCCTTTACTCTGCG for the 5' (distal end) and (SEQ ID No.: 3) GGAATTCAAGCTTGATATCCAAGGGCTACCTCGG for the 3' (proximal end) . The resulting DNA fragment was digested with EcoRI restriction endonuclease and the overlapping end of the DNA was made blunt with the Klenow fragment of DNA polymerase using standard methods. This fragment was cloned into the vector pBluescript II KS+ (Stratagene, La Jolla, CA) by digesting the pBluescript vector with the restriction endonuclease EcoRV and ligating the insert and the vector with DNA ligase. The resulting clones were isolated and transformed into E . coli DH5α cells for plasmid amplification. Plasmid was purified from the cells using the standard alkaline lysis method. This clone was designated plasmid "4A". More than 20 differences between the published sequence from Fisher rat (Ravid et al . [1991], supra) and the sequenced clone were identified. These differences are identified in Figure 4.
B. tsA58 SV40 Cloning
A DNA fragment generated by Kpnl and BamHI restriction enzyme digestion containing the wild-type SV40 virus early region was ligated into the pBluescript II KS+ vector previously digested with the restriction endonucleases Kpnl and BamHI. This ligated vector containing the SV40 insert was then digested with Hpal, removing a DNA fragment of -1.1 kb from position 3733 to 2666 of the SV40 early region. The same fragment from an SV40 clone containing the tsA58 mutation (Alanine to Valine at position 3505) described by Tegtmeyer, supra, was ligated into the vector. The resulting vector was transformed into E. coli DH5α cells for plasmid amplification. The desired plasmid was isolated from these cells and was designated plasmid "4B".
C. PF4/1-.SA5R SV40 Fusion Gene
The 4A clone described above was digested with restriction enzymes EcoRV and Spelr and the -1.1 kb fragment of the PF4 promoter containing fragment was isolated using standard methodology. The overlapping end of this promoter fragment was blunted with the Klenow fragment of DNA polymerase using standard techniques. Clone 4B was linearized at position 5187 with the restriction enzyme Ayrll, blunted with the Klenow fragment of DNA polymerase, and the PF4 promoter containing fragment was ligated into the site so that the direction of transcription of the PF4 promoter was the same as for the SV40 early region structural gene. The PF4 promoter containing sequence is shown in
Figure 2. This clone was designated plasmid "4C". The resulting fusion gene was isolated from vector sequences with restriction enzymes NotI and EcoRI and injected into fertilized mouse embryos. Plasmid 4C is deposited at the ATCC in transformed E. coli DH5α cells and is available under the accession number ATCC 69182.
D. Preparation of Embryos and Microiniection
Pregnant mare's serum ("PMS"), supplying
Follicle Stimulating Hormone ("FSH") was administered to female mice of the strain BDF2 (Charles River Labs) about three days prior to the day of microinjection. PMS (obtained from Sigma Chemicals) was prepared as a 50 I.U./ml solution in Phosphate Buffered Saline and injected interperitoneally at 0.1 ml (5 I.U.) per animal. Human Chorionic Gonadotropin ("HCG"), supplying Luteinizing Hormone ("LH") was administered 45-48 hours after the PMS injections. HCG was also prepared as a 50 I.U./ml solution in PBS and injected IP
(intraperitoneally) at 0.1 ml per animal. Females were placed with stud males of the same strain immediately after HCG injections. After mating, the females were examined for a vaginal copulation plug. The appearance of an opaque white plug indicated a successful mating. Successfully mated females were sacrificed by cervical dislocation, and both oviducts were rapidly removed and placed in M2 medium (Hogan et al . , eds.. Manipulating the Mouse Embryo : A Laboratory Manual, Cold Spring Harbor Laboratory Press, pp 249-257 [1986]) . The oviducts were transferred individually from M2 medium to PBS containing 300 μg/ml hyaluronidase (Sigma Corp., St. Louis, MO.) in a round bottom dissection slide. The embryos were teased out of the oviduct and allowed to settle at the bottom of the slide as the cumulus cells detached from the embryos. When the cumulus masses were disaggregated (about 5 minutes) the embryos were transferred through two washes of M2 medium and the fertilized embryos were separated from unfertilized and abnormal embryos. The fertilized embryos were then transferred through 5% CO2 equilibrated M16 medium (Hogan et al . , supra) , placed in equilibrated microdrop dishes containing Ml6 medium under paraffin oil and returned to the incubator.
E. Injection Procedure
Fertilized embryos were selected in Ml6 medium and incubated about 5 hours at 37°C until the pronuclei appeared. Embryos were then transferred into M2 medium in a shallow depression slide under paraffin oil and placed under the microscope. The pronuclei were easily visible under 200X magnification. Using suction on the holding pipet, a single embryo was selected and rotated such that the male pronucleus was away from the holding pipet. Approximately 200 picoliter of solution containing the DNA construct at about 1 microgram per ml was injected into the one of the pronuclei, preferably the male pronucleus. Following the injection, the embryos were returned to incubation for 18 hours and reimplanted the next day into foster pseudopregnant females (prepared as described below and in Hogan et al . , supra, pp. 132-145) . F . Re imp 1 ant at i on
Reimplantations were performed on anaesthetized mice of strain C57/BL6 x DBA2 Fl cross using a dissecting microscope. A pseudo-pregnant female mouse was anaesthetized with 0.017-0.020 ml/g body weight of avertin, injected IP. The mouse was placed under the dissecting microscope and the incision area was disinfected with 70% ethanol. The ovary was exteriorized and the bursal sac that surrounds the ovary and the oviduct was carefully pulled open. The ovary and oviduct were separated to expose the opening of the oviduct (termed the infindibulum) . Surviving embryos were then removed from the incubator and loaded into the reimplantation pipet. The tip of the pipet was inserted several millimeters into the infindibulum and gentle pressure was used to deliver the embryos into the oviduct. About 10 to 20 embryos were implanted per mouse, resulting in a litter size of 5 to 12. The ovary then was returned to the peritoneum, and the body wall and then the skin were sutured.
G. Identification of Transgenic Mice
Of 109 mice born after embryo injections,
20 contained the transgene as assayed by specific PCR amplification using the oligonucleotides described in Section A above. These results were confirmed by Southern analysis (Sambrook et al . , [1989]) using a DNA probe generated from the oligonucleotides used for PCR analysis. These transgenic mice are termed the founder mice. Two of these mice died unexpectedly after tail biopsies, having bled profusely. The remaining 18 mice were bled by tail vein nick and the blood samples were placed into a tube containing EDTA powder. H. Analysis of Blood Cell Content
Blood cell content of each transgenic founder mouse was analyzed using a Sysmex TM Cell analyzer (TOA Medical Electronics, Kobe, Japan) . Twenty microliters of blood obtained from each mouse was added to manufacturer's diluent for analysis. Platelet counts, white blood cell counts, red blood cell counts, and mean platelet volume were all obtained on that instrument. All blood cell parameters were within the range observed for the control (nontransgenic) littermate mice, except for the platelet counts. Normal platelet counts for mice are 800,000-1,200,000 cells per microliter of blood. Platelet counts of the transgenic mice are shown in Figure 3A. As is apparent, founder mice PS14, PS27, PS77, PS81, and PS102 had platelet levels that were 5-25% of the controls; founder mice PS2, PS7, PS64, PS71, and PS95 had platelet levels that were 25-60% of the controls; and mice PS22, PS24, PS25, PS28, PS29, PS32, PS43, and PS61 had platelet levels that were comparable to the levels of the control mice. Thus, the majority of the transgenic mice had thrombocytopenia.
I. Production of Fl Generation Mice
To determine whether the platelet phenotype was directly correlated with the presence and activity of the transgene construct, both hemizygous and homozygous Fl generation transgenic mice were derived from all lines except PS28, PS43, and PS61. The Fl generation was prepared by backcrossing each line to the C57/BL6 xDBA2 Fl cross mouse line.
A RNA/DNA hybridization assay (Hunt et al . , Blood 11 904-911 [1992]) was performed on DNA obtained from tail tissue of each mouse. This assay used both SV40 T antigen and mouse stem cell factor (SCF) RNA probes. The ratio between the T antigen signal and the SCF signal was used to determine the zygosity of the mice. Blood analysis was obtained for each mouse using the Sysmex TM system as described above. To assay the level of megakaryocytes in the transgenic Fl population, bone marrow cells were obtained from lines PS2, PS7, PS14, PS22, PS25, PS29, PS32, and PS77. The bone marrow cells were obtained by flushing marrow from the longbones of the hind legs using Levine's CATCH buffer (Levine, A. and Fedorko, M. J. Cell Biol . , 11:159 [1976]). These cells were stained for acetylcholinesterase, a marker for megakaryocytes (Burstein et al., J. Cell . Physiol . , 122:159-165 [1985]) and with May-Gruenwald Giesma stain. The results are shown in Figure 3C. As is apparent, there is a trend towards an inverse correlation between platelet count in the blood and megakaryocyte cell count in the bone marrow.
In addition, the spleens from these mice were dispersed and stained for acetylcholinesterase activity, and line PS14 was observed to contain about four times the number of acetylcholinesterase positive staining cells as observed in the control mice.
Examination of peripheral blood smears from lines PS2, PS7, PS14, and PS77 indicated reduced platelet levels as compared to controls, and also revealed the presence of large agranular platelets. Bone marrow smears from the same lines indicated an abnormal shape and size of the megakaryocytes.
J. Production of F2 Generation Mice
To examine the effect of gene dosage on the platelet phenotype, hemizygous Fl mice were bred together and mice homozygous for the transgene were identified for lines PS2, PS7, PS22, and PS29. Platelet counts were obtained for these mice. The platelet counts are shown in Figure 3B where the solid boxes indicate hemizygosity for the transgene, and hatched boxes indicate homozygosity for the transgene. With the exception of line PS22, the homozygous mice exhibited a more severe platelet defciency phenotype than did the hemizygous mice.
K. Identification of Megakaryocyte Leukemia
The cause of death of various transgenic mice was determined. Tissues from the PS22 line founder mouse were fixed and sectioned, and the presence of leukemic cells was observed in liver, intestine, and spleen; many of the cells tested stained positive with a polyclonal antibody directed against mouse platelets, and the nuclei of the leukemic cells were immunoreactive for an antibody to SV40 T antigen.
In addition, mice of lines PS14, PS24, and PS71 died before eight months of age. Necropsy of these animals revealed grossly enlarged spleens and mottled livers, suggesting a leukemic pathology.
L. Production of Cell Lines
Transgenic mice are examined for a moribund appearance, indicating imminent death. When such features as ruffled fur, decreased activity level, swollen abdomen, and/or a palpable spleen are observed, the mice are euthanized and the spleen, bone marrow, and lymph node tissues are removed. The tissues are immediately dispersed into suitable media such as RPMI 1640 containing a serum supplement such as fetal calf serum at 5-25% (v/v) , and appropriate growth factors including, without limitation, interleukin 3 and/or stem cell factor at appropriate levels. Incubation of the cells is at 33°C, 37°C or 39°C. The culture medium is changed regularly. After suitable time has elapsed for the cells to separate, the cells are assayed for the presence of megakaryocyte and/or platelet markers such as acetylcholinesterase (for megakaryocytes) .
DEPOSITS
Plasmid 4C containing the Sprague-Dawley rat
PF4 promoter linked to SV40 early region tsA58 mutant was deposited in E. coli host cells, under the terms of the Budapest Treaty, with DH5α the American Type Culture
Collection ("ATCC"), 12301 Parklawn Drive, Rockville, MD 20852, on January 7, 1993. Samples of these cells are available to one skilled in the art under the accession number ATCC 69182.
All literature cited herein is specifically incorporated by reference.
SEQUENCE LISTING
(1) GENERAL INFORMATION:
(i) APPLICANT: Amgen Inc.
(ii) TITLE OF INVENTION: TRANSGENIC MAMMALS
(iii) NUMBER OF SEQUENCES: 5
(iv) CORRESPONDENCE ADDRESS:
(A) ADDRESSEE: Amgen Inc.
(B) STREET: Amgen Center
1840 Dehavilland Drive
(C) CITY: Thousand Oaks
(D) STATE: California
(E) COUNTRY: United States of America
(F) ZIP: 91320-1789 (v) COMPUTER READABLE FORM:
(A) MEDIUM TYPE: Floppy Disk
(B) COMPUTER: IBM PC Compatible
(C) OPERATING SYSTEM: MS-DOS
(D) SOFTWARE: Macintosh Microsoft Word Version 5.1a (vi) CURRENT APPLICATION DATA:
(A) APPLICATION NUMBER: 08/006,082
(B) FILING DATE: 19-JAN-1993
(C) CLASSIFICATION:
(2) INFORMATION FOR SEQ ID Nθ:l: (i) SEQUENCE CHARACTERISTICS :
(A) LENGTH: 1264 base pairs
(B) TYPE: Nucleic acid
(C) STRANDEDNESS : Single stranded
(D) TOPOLOGY: Linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:
TTGGAGCTCC ACCGCGGTGG CGGCCGCTCT AGAACTAGTG GATCCCCCGG 50
GCTGCAGGAA TTCGATAATT CCTTTACTCT GCGAATGCTG AAATCTTTGG 100
TGAAGGTGGC ACAGAAGAGT TTTCTTGCTG TCCAGATTAA AATCCTCTTA 150
TCATATATAT ATATATATAT ATATATATAT GTATATATAT ATATTTATTT 200
TTTTATTTTT ATTTTTTTTT TTTTTTGCTG ACCCAGCCGA GGCCTTGAGT 250
TTCAGTTCCC TAAAGGCATA GGGATTCTGA CATGTTTTGC AGTAGCCGTT 300
GTTGTCCATG CTGAGTGTCC ATAAATGTAT GCCCCGGGGA GTTATGCTTG 350
ACTATATCAC TATGCATGGG GGGCAGATAA AGGGGCACAT AATTATAACC 400
ATATATGGCA TGAATTAATA TAGAGATCTC CAACTGTCCC AGAAAGCTTT 450
CTTCTC ACT CTTCTCCAGG GTAGAGCTGA GCAGACTAAA AGATTTTTAT 500
CAAAGAAAAG CCTTCAAATA CTACCTCAGG GATGTTTCTA AAGAGTCCTG 550
AGAAGAGCAG ACCCTGCCGC CTCCAGTAGA TTGGACAGCC GTAGCTCAGA 600
AGAGCCTCCA GAATTTCCTG CAGGAGGCTT CGGAAGGTTT CCATCGTGAG 650
GATGAAAGTC AGAAGCCATT GCCTAGCCAT TCACTTCAAT GTTTTAATGG 700
CAGAAAATAA ATTTCCAGTC TCGCATCTCT AACCACATGG CAGTCAAACT 750
CACAGCAAAT CAACAGGAAG CACGGCAGGG TGTTTGGGGT AGGGCAACCG 800
GAAGTCGGGA AGGCAACAAA TTGGTACTGA AGGTGCATGT TCTGTAAACC 850
GCATGGGGAT AGCAGAAAAT TCTCTGCCAC ATACAGCATA CCTTCTGCGA 900
AAATTCCAAC TGTTTCTACC TCTGTAGACT GTTCACATAA ATTCACATTG 950
GGGACGTGGA TCCTGCTGAC AGCTGCTGAC AGCTGGCCTC AGCTGCTGCT 1000
TCTTCTTCTT CTTCTTTTTT TTTTTTTTTT TTTCCTGTTC TATGTTGCTT 1050
TAATCTTGGC TGGCCAGATC TCAAGTACTG TTCCACAAGT GTCATTGCTT 1100
CTGTGGATCA CTTCCTCATC CCCTATCCCG GGTTTCCGGA CTGGGCTGGC 1150
AGTGAAGATA AAACGTGTCT AGAAAGTCAC AGGAGCCACT GTCTGGCACT 1200
TAGAGCCCCA GACCCCAGTT TCCCCGAGGT AGCCCTTGGA TATCAAGCTT 1250
GAATTATCAA GCTT 1264 (2) INFORMATION FOR SEQ ID NO:2 : (i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 22 base pairs
(B) TYPE: Nucleic acid
(C) STRANDEDNESS: Single stranded
(D) TOPOLOGY: Linear
(xi) SEQUENCE DESCRIPTION: SEQ ID Nθ:2: GCTTGAATTC CTTTACTCTG CG 22
(2) INFORMATION FOR SEQ ID NO:3 : (i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 34 base pairs
(B) TYPE: Nucleic acid
(C) STRANDEDNESS: Single stranded
(D) TOPOLOGY: Linear
(xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: GGAATTCAAG CTTGATATCC AAGGGCTACC TCGG 34
(2) INFORMATION FOR SEQ ID NO: 4: (i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 1160 base pairs
(B) TYPE: Nucleic acid
(C) STRANDEDNESS: Single stranded
(D) TOPOLOGY: Linear
(xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:
AATTCCTTTA CTCTGCGAAT GCTGAAATCT TTGGTGAAGG TGGCACAGAA 50
GAGTTTTCTT GCTGTCCAGA TTAAAATCCT CTTATCATAT ATATATATAT 100
ATATATATAT ATATGTATAT ATATATATTT ATTTTTTTAT TTTTATTTTT 150
TTTTTTTTTT GCTGACCCAG CCGAGGCCTT GAGTTTCAGT TCCCTAAAGG 200
CATAGGGATT CTGACATGTT TTGCAGTAGC CGTTGTTGTC CATGCTGAGT 250
GTCCATAAAT GTATGCCCCG GGGAGTTATG CTTGACTATA TCACTATGCA 300
TGGGGGGCAG ATAAAGGGGC ACATAAT AT AACCAT TAT GGCATGAATT 350
AATATAGAGA TCTCCAACTG TCCCAGAAAG CTTTCTTCTC TACTCTTCTC 400
CAGGGTAGAG CTGAGCAGAC TAAAAGATTT TTATCAAAGA AAAGCCTTCA 450
AATACTACCT CAGGGATGTT TCTAAAGAGT CCTGAGAAGA GCAGACCCTG 500
CCGCCTCCAG TAGATTGGAC AGCCGTAGCT CAGAAGAGCC TCCAGAATTT 550
CCTGCAGGAG GCTTCGGAAG GTTTCCATCG TGAGGATGAA AGTCAGAAGC 600
CATTGCCTAG CCATTCACTT CAATGTTTTA ATGGCAGAAA ATAAATTTCC 650
AGTCTCGCAT CTCTAACCAC ATGGCAGTCA AACTCACAGC AAATCAACAG 700
GAAGCACGGC AGGGTGTTTG GGGTAGGGCA ACCGGAAGTC GGGAAGGCAA 750
CAAATTGGTA CTGAAGGTGC ATGTTCTGTA AACCGCATGG GGATAGCAGA 800
AAATTCTCTG CCACATACAG CATACCTTCT GCGAAAATTC CAACTGTTTC 850
TACCTCTGTA GACTGTTCAC ATAAATTCAC ATTGGGGACG TGGATCCTGC 900
TGACAGCTGC TGACAGCTGG CCTCAGCTGC TGCTTCTTCT TCTTCTTCTT 950 ττττττττττ τττττττccτ GTTCTATGTT GCTTTAATCT TGGCTGGCCA 1000
GATCTCAAGT ACTGTTCCAC AAGTGTCATT GCTTCTGTGG ATCACTTCCT 1050
CATCCCCTAT CCCGGGTTTC CGGACTGGGC TGGCAGTGAA GATAAAACGT 1100
GTCTAGAAAG TCACAGGAGC CACTGTCTGG CACTTAGAGC CCCAGACCCC 1150
AGTTTCCCCG 1160
(2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1142 base pairs (B) TYPE: Nucleic acid
(C) STRANDEDNESS: Single stranded
(D) TOPOLOGY: Linear
(xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:
AATTCCTTTA CTCTGCGAAT GCTGAAATCT TTGGTGAAGG TGGCACAGAA 50
GAGTTTTCTT GCTGTCCAGA TTAAAATCCT CTTATCATAT ATATATGTAT 100
ATATATATAT ATATATATAT ATATATTTTT TTTTTTTTTT TTTTTTTTTT 150
TGCTGACCCA GCCGAGGCCT TGAGTTTCAG TTCCCTAAAG GCATAGGGAT 200
TCTGACATGT TTTGCAGTAG CCGTTGTTGT CCATGCTGAG TGTCCATAAA 250
TGTATGCCCC GGGGAGTTAT GCTTGACTAT ATCACTATGC ATGGGGGGCA 300
GATAAAGGGG CACATAATTA TAACCA ATA TGGCATGAAT TAATATAGAG 350
ATCTCCAACT GTCCCAGAAA GCTTTCTTCT CTACTCTTCT CCAGGGTAGA 400
GCTGAGCAGA CTAAAAGATT TTATCAAAGA AAAGCCTTCA AATACTACCT 450
CAGGGATGTT TCTAAAGAGT CCTGAGAAGA GCAGACCCTG CCGCCTCCAG 500
TAGATTGGAC AGCCGTAGCT CAGAAGAGCC TCCAGAATTT CCTGCAGGAG 550
GCTTCAGAAG GTTTCCATCG TGAGGATGAA AGTCAGAAGC CATTGCCTAG 600
CCATTCACTT CAATGTTTTA ATGGCAGAAA ATAAATTTCC AGTCACGCAT 650
CTCTAACCAC ATGGCAGTCA AACTCACAGC AAATCAACAG GAAAGCACGG 700
CAGGGTGTTT GGGGTCGGGC AACCGGAAGT CGGGAAGGCA ACAAATTGGT 750
ACTGAAGGTG CATGTTCTGT AAACCGCATG GGGATAGCAG AAAATTCTCT 800 GCCACATACA GCATACCTTC TGCGAAAATT CCAACTGTTT CTACCTCTGT 850
AGACTGTTCA CATAAATTCA CATTGGGGAC GTGGATCCTG CTGACAGCTG 900
CTGACAGCTG GCCTCAGCTG CTTCTTTTTT TTTTTTTTTT TTTTTTTTTT 950
CCTGTTCTAT GTTGCTTTAA TCTTGGCTGG CCAGATCTCA AGTACTGTTC 1000
CACAAGTGTC ATTGCTTCTG TGGATCACTT CCTCATCCCC ATCCCGGGTT 1050
TCCGGACTGG GCTGGCAGTG AAGATAAAAC GTGTCTAGAA AGTCACAGGA 1100
GCCACTGTCT GGCACTTAGA GCCCCAGACC CCAGTTTCCC CG 1142

Claims

WE CLAIM:
1. A vector comprising nucleic acid encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor or megakaryocyte promoter.
2. The vector of claim 1 wherein the promoter is selected from the group consisting of: PF4 and MPL.
3. A mammal containing in its DNA the DNA encoding the SV40 early region tsA58 mutant operably linked to a promoter selected from the group consisting of: PF4 and MPL
4. The progeny of the mammal of claim 3.
5. The mammal of claim 3 that is a mouse.
6. The mammal of claim 3 wherein incorporation of said DNA encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor promoter or a megakaryocyte promoter confers thrombocytopenia upon said mammal.
7. The mammal of claim 3 wherein incorporation of said DNA encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor promoter or megakaryocyte promoter confers megakaryocyte leukemia upon said mammal.
8. The mammal of claim 6 that is a mouse.
9. The mammal of claim 7 that is a mouse.
10. The progeny of the mouse of claim 8.
11. The progeny of the mouse of claim 9.
12. A mammalian cell line containing in its DNA the DNA encoding the tsA58 SV40 early region operably linked to a platelet precursor promoter or a megakaryocyte promoter.
13. The cell line of claim 12 derived from murine tissue selected from the group consisting of: spleen, bone marrow and lymph node.
14. A method of preparing a mammal with a decreased platelet count, comprising: a) introducing into a fertilized mammalian embryo a vector comprising nucleic acid encoding the
SV40 early region tsA58 mutant operably linked to a platelet precursor promoter or a megakaryocyte promoter; b) implanting said embryo in a surrogate mother to produce offspring; and c) screening said offspring for decreased platelet counts.
15. The method of claim 14 wherein the mammal is a mouse.
16. The method of claim 15 wherein the nucleic acid is introduced into embryos using a microinjection procedure.
17. A method of preparing a mammal with megakaryocyte leukemia, comprising: a) introducing into a fertilized mammalian embryo a vector comprising nucleic acid encoding the SV40 early region tsA58 mutant operably linked to a platelet precursor promoter or a megakaryocyte promoter; b) implanting said transformed embryo into a surrogate host to produce offspring; and c) screening said offspring for megakaryocyte leukemia.
18. A nucleic acid sequence encoding the rat PF4 promoter sequence of Figure 2.
19. The nucleic acid sequence encoding rat
PF4 promoter activity comprised on the sequence of claim 18.
PCT/US1994/000526 1993-01-19 1994-01-14 Transgenic mammals WO1994016556A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP6517125A JPH08506014A (en) 1993-01-19 1994-01-14 Transgenic mammal
AU60888/94A AU6088894A (en) 1993-01-19 1994-01-14 Transgenic mammals

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/006,082 US5489743A (en) 1993-01-19 1993-01-19 Transgenic animal models for thrombocytopenia
US08/006,082 1993-01-19

Publications (1)

Publication Number Publication Date
WO1994016556A1 true WO1994016556A1 (en) 1994-08-04

Family

ID=21719213

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/000526 WO1994016556A1 (en) 1993-01-19 1994-01-14 Transgenic mammals

Country Status (6)

Country Link
US (1) US5489743A (en)
EP (1) EP0607925A3 (en)
JP (1) JPH08506014A (en)
AU (1) AU6088894A (en)
CA (1) CA2153502A1 (en)
WO (1) WO1994016556A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004060055A1 (en) * 2002-12-27 2004-07-22 Chugai Seiyaku Kabushiki Kaisha Wt1 transgenic animal

Families Citing this family (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5858747A (en) * 1994-07-20 1999-01-12 Cytotherapeutics, Inc. Control of cell growth in a bioartificial organ with extracellular matrix coated microcarriers
US6353151B1 (en) 1996-09-26 2002-03-05 University Technology Corporation Transgenic model for heart failure
US5919656A (en) * 1996-11-15 1999-07-06 Amgen Canada Inc. Genes encoding telomerase protein 1
US7390891B1 (en) 1996-11-15 2008-06-24 Amgen Inc. Polynucleotides encoding a telomerase component TP2
WO1999043697A1 (en) * 1998-02-25 1999-09-02 The Board Of Regents Of The University And Community College System Of Nevada On Behalf Of The University Of Nevada-Reno Manganese superoxide dismutase exon 3-deleted isoforms and nucleic acid molecules encoding the isoforms
US7157083B2 (en) * 1998-04-17 2007-01-02 Surrogate Pharmaceutical Pathways, Llc Compositions and methods for treating retroviral infections
US6492138B1 (en) 1998-05-21 2002-12-10 Amgen Canada Inc. Polynucleotides encoding a novel SHC-binding protein
CA2328425A1 (en) * 1998-05-22 1999-12-02 Osiris Therapeutics, Inc. Production of megakaryocytes by co-culturing human mesenchymal stem cells with cd34+ cells
US5973119A (en) * 1998-06-05 1999-10-26 Amgen Inc. Cyclin E genes and proteins
US6344541B1 (en) 1998-09-25 2002-02-05 Amgen Inc. DKR polypeptides
WO2000058479A1 (en) 1999-03-26 2000-10-05 Amgen Inc. Beta secretase genes and polypeptides
US20030096355A1 (en) * 1999-07-09 2003-05-22 Ke Zhang Isolation, identification and characterization of ymkz5, a novel member of the TNF-receptor supergene family
US6627199B1 (en) 1999-07-09 2003-09-30 Amgen Inc Isolation, identification and characterization of tmst2, a novel member of the TNF-receptor supergene family
JP2003506088A (en) * 1999-08-04 2003-02-18 アムジェン インコーポレーテッド Fhm, a new member of the TNF ligand supergene family
AU6517800A (en) 1999-08-04 2001-03-05 Amgen, Inc. Ntr3, a member of the tnf-receptor supergene family
US7408047B1 (en) * 1999-09-07 2008-08-05 Amgen Inc. Fibroblast growth factor-like polypeptides
US7459540B1 (en) 1999-09-07 2008-12-02 Amgen Inc. Fibroblast growth factor-like polypeptides
US6900043B1 (en) * 1999-09-21 2005-05-31 Amgen Inc. Phosphatases which activate map kinase pathways
US6864355B1 (en) 2000-05-02 2005-03-08 Yale University Inhibition of NF-κB activation by blockade of IKKβ-NEMO interactions at the NEMO binding domain
US6586390B1 (en) 2000-01-21 2003-07-01 Hyseq, Inc. Methods and materials relating to novel prothrombinase-like polypeptides and polynucleotides
EP1240350A4 (en) 1999-12-23 2003-11-19 Millennium Pharm Inc P2y12 receptor
AR030554A1 (en) 2000-03-16 2003-08-27 Amgen Inc SIMILAR MOLECULES TO IL-17 RECEPTORS AND USES OF THE SAME
US7514239B2 (en) 2000-03-28 2009-04-07 Amgen Inc. Nucleic acid molecules encoding beta-like glycoprotein hormone polypeptides and heterodimers thereof
ES2529300T3 (en) 2000-04-12 2015-02-18 Novozymes Biopharma Dk A/S Albumin fusion proteins
EP2077279B1 (en) 2000-06-28 2012-09-05 Amgen Inc. Thymic stromal lymphopoietin receptor molecules and uses thereof
AU2002359666A1 (en) 2001-12-10 2003-06-23 California Institute Of Technology Method for the generation of antigen-specific lymphocytes
EP2261250B1 (en) 2001-12-21 2015-07-01 Human Genome Sciences, Inc. GCSF-Albumin fusion proteins
CN1646154B (en) 2002-02-07 2010-12-01 诺维信生物制药英国有限公司 Albumin-fused anti-angiogenesis peptides
US7662924B2 (en) * 2002-02-22 2010-02-16 The Board Of Trustees Of The University Of Illinois Beta chain-associated regulator of apoptosis
US20040025194A1 (en) * 2002-02-22 2004-02-05 Board Of Trustees Of The University Of Illinois Beta chain-associated regulator of apoptosis
KR20050056250A (en) 2002-10-18 2005-06-14 주식회사 엘지생명과학 Gene families associated with cancers
US20040126885A1 (en) * 2002-11-05 2004-07-01 Cines Douglas B. Delivery vehicle for recombinant proteins
ATE539086T1 (en) * 2003-12-03 2012-01-15 Monika Kroez INTERLEUKIN-11 FUSION PROTEINS
SE0303268D0 (en) * 2003-12-05 2003-12-05 Angiogenetics Sweden Ab Angiogenesis affecting polypeptides, proteins, and compositions, and methods of use thereof
US20080317761A1 (en) * 2004-04-28 2008-12-25 The Trustees Of The University Of Pennsylvania Peptide-Mediated Protein Transduction Into Cells of the Hematopoietic Lineage
EP2298897B1 (en) 2004-09-02 2013-08-14 Yale University Regulation of oncogenes by microRNAs
US8354384B2 (en) * 2005-06-23 2013-01-15 Yale University Anti-aging micrornas
US9505823B2 (en) * 2006-08-07 2016-11-29 TEV A Biopharmaceuticals USA, Inc. Albumin-insulin fusion proteins
CN101260398B (en) * 2007-03-07 2013-06-05 舒泰神(北京)生物制药股份有限公司 Nerve growth factor gene positioning reconstruction animal and its preparation method and application
JP2011515078A (en) * 2008-03-01 2011-05-19 アブラクシス バイオサイエンス リミテッド ライアビリティー カンパニー Treatment, diagnosis, and antagonist discovery method using SPARC specific miRNA
WO2009137660A2 (en) * 2008-05-07 2009-11-12 Abraxis Bioscience, Llc Enhancement of drug therapy by mirna
JOP20190083A1 (en) 2008-06-04 2017-06-16 Amgen Inc Fgf21 mutant fusion polypeptides and uses thereof
WO2010042747A2 (en) 2008-10-10 2010-04-15 Amgen Inc. Fgf21 mutants and uses thereof
JP2012525847A (en) 2009-05-05 2012-10-25 アムジエン・インコーポレーテツド FGF21 variants and uses thereof
PE20120358A1 (en) 2009-05-05 2012-04-26 Amgen Inc FGF21 MUTANTS AND USES OF THEM
MX2011013903A (en) * 2009-06-17 2012-05-08 Amgen Inc Chimeric fgf19 polypeptides and uses thereof.
CA2782814A1 (en) * 2009-12-02 2011-06-09 Amgen Inc. Binding proteins that bind to human fgfr1c, human .beta.-klotho and both human fgfr1c and human .beta.-klotho
UA109888C2 (en) * 2009-12-07 2015-10-26 ANTIBODY OR ANTIBODILITY ANTIBODY OR ITS BINDING TO THE β-CLOTE, FGF RECEPTORS AND THEIR COMPLEXES
US9517264B2 (en) 2010-04-15 2016-12-13 Amgen Inc. Human FGF receptor and β-Klotho binding proteins
US8759313B2 (en) 2011-08-03 2014-06-24 The Charlotte-Mecklenburg Hospital Authority Treatment of fibrosis using microRNA 19b
US9540657B2 (en) 2012-05-25 2017-01-10 California Institute Of Technology Expression of secreted and cell-surface polypeptides
US11044896B2 (en) 2013-09-12 2021-06-29 Icahn School Of Medicine At Mount Sinai T cell receptors that are specific to a fluorescent protein, transgenic animals and methods of their making, isolated T cells, and methods of use

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4873191A (en) * 1981-06-12 1989-10-10 Ohio University Genetic transformation of zygotes
WO1991013150A1 (en) * 1990-02-20 1991-09-05 Ludwig Institute For Cancer Research Transgenic animals, cells and cell lines therefrom, and their use

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4870009A (en) * 1982-11-22 1989-09-26 The Salk Institute For Biological Studies Method of obtaining gene product through the generation of transgenic animals
US4736866B1 (en) * 1984-06-22 1988-04-12 Transgenic non-human mammals
US5175385A (en) * 1987-09-03 1992-12-29 Ohio University/Edison Animal Biotechnolgy Center Virus-resistant transgenic mice
JPH03504799A (en) * 1988-04-12 1991-10-24 マサチューセッツ・インスティチュート・オブ・テクノロジー How to manipulate eukaryotic cell types
US5162215A (en) * 1988-09-22 1992-11-10 Amgen Inc. Method of gene transfer into chickens and other avian species
US5175384A (en) * 1988-12-05 1992-12-29 Genpharm International Transgenic mice depleted in mature t-cells and methods for making transgenic mice
US5175383A (en) * 1989-02-17 1992-12-29 President And Fellows Of Harvard College Animal model for benign prostatic disease
WO1992006190A1 (en) * 1990-10-01 1992-04-16 Massachusetts Institute Of Technology Transgenic model for selective targeting of gene products with a megakaryocyte promoter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4873191A (en) * 1981-06-12 1989-10-10 Ohio University Genetic transformation of zygotes
WO1991013150A1 (en) * 1990-02-20 1991-09-05 Ludwig Institute For Cancer Research Transgenic animals, cells and cell lines therefrom, and their use

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
J.N. GEORGE et al., "Hematology", Fourth Edition, published 1990, by MCGRAW HILL PUBLISHERS, NEW YORK, pages 1343-1351. *
MOLECULAR AND CELLULAR BIOLOGY, Volume 11, No. 12, issued December 1991, K. RAVID et al., "Transcriptional Regulation of the Rat Platelet Factor 4 Gene: Interaction Between an Enhancer/Silencer Domain and the GATA Site", pages 6116-6127. *
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCE USA, Volume 88, issued February 1991, K. RAVID et al., "Selective Targeting of Gene Products with the Megakarocyte Platelet Factor 4 Promoter", pages 1521-1525. *
SCIENCE, Volume 176, issued 14 April 1972, G.T. DIAMONDOPOULOS, "Leukemia, Lymphoma, and Osteosarcoma Induced in the Syrian Golden Hamster by Simian Virus 40", pages 173-175. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004060055A1 (en) * 2002-12-27 2004-07-22 Chugai Seiyaku Kabushiki Kaisha Wt1 transgenic animal

Also Published As

Publication number Publication date
EP0607925A2 (en) 1994-07-27
JPH08506014A (en) 1996-07-02
AU6088894A (en) 1994-08-15
EP0607925A3 (en) 1995-12-13
US5489743A (en) 1996-02-06
CA2153502A1 (en) 1994-08-04

Similar Documents

Publication Publication Date Title
US5489743A (en) Transgenic animal models for thrombocytopenia
US6664107B1 (en) CD45 disrupted nucleic acid
CA2182958A1 (en) Mammal with enhanced liver expression of a transgene
EP0700435A1 (en) Transgenic mammals lacking expression of particular cd45 isoforms
Rosenfeld et al. Transgenic mice: applications to the study of the nervous system
US7626074B2 (en) Method of screening candidate drugs for the treatment of leukemia
US5728915A (en) Transgenic mice which express simian SV 40 T-antigen under control of the retinoblastoma gene promoter
US5545563A (en) Human C/EBP gene and vectors for its expression
US6255555B1 (en) Transgenic mouse expressing human fusin and human CD4
US6172278B1 (en) Ikaros transgenic cells and mice
US6077990A (en) PAR2 modified transgenic mice
JP2005510241A6 (en) Transgenic non-human mammal as a human disease model derived from stem cells
AU6935694A (en) Transgenic production of ec-sod
WO1993004168A1 (en) Transgenic non-human animal model for developing and testing therapies to treat sepsis
JPH11239430A (en) Transgenic mammal
AU1075895A (en) Sepsis model
EP0733105A1 (en) Enhanced transgene expression in specific tissues of the gastrointestinal tract
JP2003116407A (en) Radixin knock-out animal

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 2153502

Country of ref document: CA

122 Ep: pct application non-entry in european phase