RESUMO
The development of a complex multicellular organism requires a coordination of growth and cell division under the control of patterning mechanisms. Studies in yeast have pioneered our understanding of the relationship between growth and cell division. In recent years, many of the pathways that regulate growth in multicellular eukaryotes have been identified. This work has revealed interesting and unexpected relationships between mechanisms that regulate growth and the cell cycle machinery.
Assuntos
Ciclo Celular , Divisão Celular , Drosophila/crescimento & desenvolvimento , Leveduras/crescimento & desenvolvimento , Animais , Quinases Ciclina-Dependentes/fisiologia , Ciclinas/fisiologia , Drosophila/citologia , Insulina/fisiologia , Modelos Biológicos , Proteínas Proto-Oncogênicas/fisiologia , Proteínas Repressoras/fisiologia , Transdução de Sinais , Leveduras/citologiaRESUMO
During Drosophila development and mammalian embryogenesis, exit from the cell cycle is contingent on tightly controlled downregulation of the activity of Cyclin E-Cdk2 complexes that normally promote the transition from G1 to S phase. Although protein degradation has a crucial role in downregulating levels of Cyclin E, many of the proteins that function in degradation of Cyclin E have not been identified. In a screen for Drosophila mutants that display increased cell proliferation, we identified archipelago, a gene encoding a protein with an F-box and seven tandem WD (tryptophan-aspartic acid) repeats. Here we show that archipelago mutant cells have persistently elevated levels of Cyclin E protein without increased levels of cyclin E RNA. They are under-represented in G1 fractions and continue to proliferate when their wild-type neighbours become quiescent. The Archipelago protein binds directly to Cyclin E and probably targets it for ubiquitin-mediated degradation. A highly conserved human homologue is present and is mutated in four cancer cell lines including three of ten derived from ovarian carcinomas. These findings implicate archipelago in developmentally regulated degradation of Cyclin E and potentially in the pathogenesis of human cancers.
Assuntos
Proteínas de Ciclo Celular/fisiologia , Transformação Celular Neoplásica , Ciclina E/metabolismo , Proteínas F-Box , Neoplasias/metabolismo , Ubiquitina-Proteína Ligases , Sequência de Aminoácidos , Animais , Ciclo Celular , Proteínas de Ciclo Celular/genética , Divisão Celular , Transformação Celular Neoplásica/genética , Drosophila , Proteína 7 com Repetições F-Box-WD , Feminino , Humanos , Masculino , Dados de Sequência Molecular , Mutação , Neoplasias/etiologia , Neoplasias/genética , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Células Fotorreceptoras de Invertebrados/citologia , Células Fotorreceptoras de Invertebrados/metabolismo , Ligação Proteica , Células Tumorais CultivadasRESUMO
During the past year, the Drosophila genome has been sequenced. More than 60% of genes implicated in human disease have Drosophila orthologues. Developments in RNA-mediated interference and homologous recombination have made 'reverse genetics' feasible in Drosophila. Conventional Drosophila genetics is being used increasingly to place human disease genes of unknown function in the context of functional pathways.
Assuntos
Drosophila melanogaster/genética , Predisposição Genética para Doença/genética , Animais , Doença , HumanosRESUMO
The inherited human disease tuberous sclerosis, characterized by hamartomatous tumors, results from mutations in either TSC1 or TSC2. We have characterized mutations in the Drosophila Tsc1 and Tsc2/gigas genes. Inactivating mutations in either gene cause an identical phenotype characterized by enhanced growth and increased cell size with no change in ploidy. Overall, mutant cells spend less time in G1. Coexpression of both Tsc1 and Tsc2 restricts tissue growth and reduces cell size and cell proliferation. This phenotype is modulated by manipulations in cyclin levels. In postmitotic mutant cells, levels of Cyclin E and Cyclin A are elevated. This correlates with a tendency for these cells to reenter the cell cycle inappropriately as is observed in the human lesions.
Assuntos
Ciclo Celular/fisiologia , Genes Supressores de Tumor/genética , Células Fotorreceptoras de Invertebrados/citologia , Proteínas/genética , Proteínas Repressoras/genética , Esclerose Tuberosa/genética , Animais , Tamanho Celular , Ciclina A/metabolismo , Ciclina E/metabolismo , DNA/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Feminino , Citometria de Fluxo , Corantes Fluorescentes/metabolismo , Proteínas de Fluorescência Verde , Humanos , Imuno-Histoquímica , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Fenótipo , Células Fotorreceptoras de Invertebrados/fisiologia , Células Fotorreceptoras de Invertebrados/ultraestrutura , Ploidias , Proteínas/metabolismo , Proteínas Repressoras/metabolismo , Esclerose Tuberosa/fisiopatologia , Proteína 1 do Complexo Esclerose Tuberosa , Proteína 2 do Complexo Esclerose Tuberosa , Proteínas Supressoras de TumorRESUMO
The Cip/Kip family of cyclin-dependent kinase inhibitors (CKIs) has been implicated in mediating cell cycle arrest prior to terminal differentiation. In many instances, increased expression of CKIs immediately precedes mitotic arrest. However, the mechanism that activates CKI expression in cells that are about to stop dividing has remained elusive. Here we have addressed this issue by investigating the expression pattern of dacapo, a Cip/Kip CKI in Drosophila. We show that the accumulation of dacapo RNA and protein requires Cyclin E and that increased expression of Cyclin E can induce dacapo expression. We also show that the oscillation of the Cyclin E and Dacapo proteins are tightly coupled during ovarian endocycles. Our results argue for a mechanism where Cyclin E/Cdk activity induces Dacapo expression but only within certain windows that are permissive for dacapo expression.
Assuntos
Ciclina E/metabolismo , Quinases Ciclina-Dependentes/antagonistas & inibidores , Proteínas de Drosophila , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/genética , Proteínas Nucleares/genética , Animais , Ciclina E/genética , Drosophila/embriologia , Drosophila/genética , Proteínas de Insetos/metabolismo , Mutagênese , Proteínas Nucleares/metabolismoRESUMO
A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.
Assuntos
Caenorhabditis elegans/genética , Drosophila melanogaster/genética , Genoma , Proteoma , Saccharomyces cerevisiae/genética , Animais , Apoptose/genética , Evolução Biológica , Caenorhabditis elegans/química , Caenorhabditis elegans/fisiologia , Adesão Celular/genética , Ciclo Celular/genética , Drosophila melanogaster/química , Drosophila melanogaster/fisiologia , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Genes Duplicados , Doenças Genéticas Inatas/genética , Genética Médica , Proteínas de Helminto/química , Proteínas de Helminto/genética , Humanos , Imunidade/genética , Proteínas de Insetos/química , Proteínas de Insetos/genética , Família Multigênica , Neoplasias/genética , Estrutura Terciária de Proteína , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/fisiologia , Transdução de Sinais/genéticaRESUMO
The Ras-related Rap GTPases are highly conserved across diverse species but their normal biological function is not well understood. Initial studies in mammalian cells suggested a role for Rap as a Ras antagonist. More recent experiments indicate functions in calcium- and cAMP-mediated signaling and it has been proposed that protein kinase A-mediated phosphorylation activates Rap in vivo. We show that Ras1-mediated signaling pathways in Drosophila are not influenced by Rap1 levels, suggesting that Ras1 and Rap1 function via distinct pathways. Moreover, a mutation that abolishes the putative cAMP-dependent kinase phosphorylation site of Drosophila Rap1 can still rescue the Rap1 mutant phenotype. Our experiments show that Rap1 is not needed for cell proliferation and cell-fate specification but demonstrate a critical function for Rap1 in regulating normal morphogenesis in the eye disk, the ovary and the embryo. Rap1 mutations also disrupt cell migrations and cause abnormalities in cell shape. These findings indicate a role for Rap proteins as regulators of morphogenesis in vivo.
Assuntos
Proteínas de Ligação ao GTP/fisiologia , Morfogênese/fisiologia , Sequência de Aminoácidos , Animais , Sítios de Ligação/genética , Divisão Celular , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Drosophila/genética , Drosophila/crescimento & desenvolvimento , Drosophila/fisiologia , Olho/crescimento & desenvolvimento , Feminino , Proteínas de Ligação ao GTP/genética , Genes de Insetos , Mutação , Oogênese , Fenótipo , Fosforilação , Transdução de Sinais , Proteínas rap de Ligação ao GTP , Proteínas ras/metabolismoRESUMO
The activity of Ras family proteins is modulated in vivo by the function of GTPase activating proteins, which increase their intrinsic rate of GTP hydrolysis. We have isolated cDNAs encoding a GAP for the Drosophila Rap1 GTPase. Drosophila Rapgap1 encodes an 850-amino acid protein with a central region that displays substantial sequence similarity to human RapGAP. This domain, when expressed in Escherichia coli, potently stimulates Rap1 GTPase activity in vitro. Unlike Rap1, which is ubiquitously expressed, Rapgap1 expression is highly restricted. Rapgap1 is expressed at high levels in the developing photoreceptor cells and in the optic lobe. Rapgap1 mRNA is also localized in the pole plasm in an oskar-dependent manner. Although mutations that completely abolish Rapgap1 function display no obvious phenotypic abnormalities, overexpression of Rapgap1 induces a rough eye phenotype that is exacerbated by reducing Rap1 gene dosage. Thus, Rapgap1 can function as a negative regulator of Rap1-mediated signaling in vivo.
Assuntos
Proteínas de Drosophila , Drosophila/genética , Proteínas de Ligação ao GTP/metabolismo , Proteínas Ativadoras de GTPase , Genes de Insetos , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Proteínas de Insetos/genética , Proteínas/genética , Sequência de Aminoácidos , Animais , Ativação Enzimática/genética , Proteínas de Ligação ao GTP/genética , Regulação da Expressão Gênica , Humanos , Proteínas de Insetos/análise , Proteínas de Insetos/metabolismo , Dados de Sequência Molecular , Proteínas/metabolismo , Proteínas rap de Ligação ao GTPRESUMO
The Drosophila fat facets gene encodes a deubiquitinating enzyme that regulates a cell communication pathway essential very early in eye development, prior to facet assembly, to limit the number of photoreceptor cells in each facet of the compound eye to eight. The Fat facets protein facilitates the production of a signal in cells outside the developing facets that inhibits neural development of particular facet precursor cells. Novel gain-of-function mutations in the Drosophila Rap1 and Ras1 genes are described herein that interact genetically with fat facets mutations. Analysis of these genetic interactions reveals that Fat facets has an additional function later in eye development involving Rap1 and Ras1 proteins. Moreover, the results suggest that undifferentiated cells outside the facet continue to influence facet assembly later in eye development.
Assuntos
Caderinas , Drosophila/embriologia , Drosophila/genética , Olho/embriologia , Proteínas de Ligação ao GTP/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Membrana/genética , Proteínas ras/genética , Sequência de Aminoácidos , Animais , Dados de Sequência Molecular , Mutação , Transdução de Sinais/genética , Proteínas rap de Ligação ao GTPRESUMO
The neurofibromatosis type 1 (NF1) tumor suppressor protein is thought to restrict cell proliferation by functioning as a Ras-specific guanosine triphosphatase-activating protein. However, Drosophila homozygous for null mutations of an NF1 homolog showed no obvious signs of perturbed Ras1-mediated signaling. Loss of NF1 resulted in a reduction in size of larvae, pupae, and adults. This size defect was not modified by manipulating Ras1 signaling but was restored by expression of activated adenosine 3', 5'-monophosphate-dependent protein kinase (PKA). Thus, NF1 and PKA appear to interact in a pathway that controls the overall growth of Drosophila.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteínas de Drosophila , Drosophila/genética , Proteínas de Insetos/metabolismo , Proteínas do Tecido Nervoso , Proteínas Ativadoras de ras GTPase , Sequência de Aminoácidos , Animais , Contagem de Células , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/genética , Drosophila/citologia , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , GTP Fosfo-Hidrolases/metabolismo , Genes de Insetos , Proteínas de Insetos/química , Proteínas de Insetos/genética , Dados de Sequência Molecular , Mutação , Neurofibromina 1 , Fenótipo , Proteínas/química , Proteínas/genética , Proteínas Recombinantes de Fusão/farmacologia , Transdução de Sinais , Proteínas ras/metabolismoRESUMO
In a screen for genes that interact with the Rap1 GTPase, we have identified a Drosophila gene, dacapo (dap), which is a member of the p21/p27 family of cdk inhibitors. Unlike mammalian cdk inhibitors studied to date, dap is essential for normal embryonic development. Dacapo inhibits cyclin-cdk activity in vitro. Overexpressing dap during eye development interferes with cell cycle progression and interacts genetically with the retinoblastoma homolog (Rbf) and cyclin E. dap expression in embryos parallels the exit of cells from the cell cycle. dap mutant embryos delay the normal cell cycle exit during development; many cells complete an additional cycle and subsequently become quiescent. Thus, dap functions during embryogenesis to achieve a precisely timed exit from the cell cycle.
Assuntos
Quinases relacionadas a CDC2 e CDC28 , Ciclo Celular , Quinases Ciclina-Dependentes/antagonistas & inibidores , Ciclinas/antagonistas & inibidores , Proteínas de Drosophila , Drosophila melanogaster/embriologia , Inibidores do Crescimento , Proteínas de Insetos/fisiologia , Proteínas Nucleares/fisiologia , Proteínas Quinases , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Clonagem Molecular , Quinase 2 Dependente de Ciclina , Drosophila melanogaster/enzimologia , Inibidores Enzimáticos , Células Epidérmicas , Olho/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Genes Letais , Dados de Sequência Molecular , Mutagênese Insercional , Inibidores de Proteínas Quinases , RNA Mensageiro/genética , Alinhamento de SequênciaRESUMO
Cell proliferation and cell fate specification are under strict spatiotemporal control in the developing Drosophila eye. Cells excluded from five-cell preclusters synchronously enter a single additional cell cycle, the second mitotic wave, after which the remaining cells are sequentially recruited. When the second mitotic wave was blocked with the human cyclin-dependent kinase inhibitor p21CIP1/WAF1, each cell type was still specified. Hence, cell fate determination is regulated independently of the division pattern of precursor cells. However, the second mitotic wave is needed to generate appropriate numbers of each cell type. Moreover, p21 can arrest precursor cell proliferation and allow appropriate fate choice in vivo.
Assuntos
Diferenciação Celular , Drosophila melanogaster/citologia , Mitose , Células Fotorreceptoras de Invertebrados/citologia , Animais , Animais Geneticamente Modificados , Apoptose , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/genética , Ciclinas/fisiologia , Drosophila melanogaster/crescimento & desenvolvimento , Inibidores Enzimáticos , Olho/citologia , Olho/crescimento & desenvolvimento , Olho/ultraestrutura , Microscopia Eletrônica de Varredura , Morfogênese , Células Fotorreceptoras de Invertebrados/crescimento & desenvolvimento , Células Fotorreceptoras de Invertebrados/ultraestrutura , TransgenesRESUMO
The rho family of GTPases has been implicated in regulating changes in cell morphology in response to extracellular signals. We have cloned three widely expressed members of this family from Drosophila melanogaster; a rho homologue (Rho1) and two rac homologues (Rac1 and Rac2). Flies harbouring a Rho1 transgene that is specifically expressed in the eye exhibit a dramatic dose dependent disruption of normal eye development. Flies bearing at least two copies of the transgene display a severe rough eye phenotype characterized by missing secondary and tertiary pigment cells, a substantial reduction in the number of photoreceptor cells and a grossly abnormal morphology of the rhabdomeres. Cell fate determination in the imaginal disc occurs normally and abnormalities become manifest late in pupariation, coincident with the phase when the cells undergo major morphological changes. This phenotype is modified by mutations at several other loci that have been implicated in signal transduction, but not by mutations in ras pathway components.
Assuntos
Drosophila melanogaster/enzimologia , Proteínas Fúngicas/fisiologia , GTP Fosfo-Hidrolases/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Retina/enzimologia , Proteínas rho de Ligação ao GTP , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Sequência de Bases , Clonagem Molecular , DNA Complementar , Proteínas de Drosophila , Drosophila melanogaster/embriologia , Proteínas Fúngicas/genética , GTP Fosfo-Hidrolases/genética , Proteínas de Ligação ao GTP/genética , Humanos , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Fenótipo , Retina/embriologia , Retina/ultraestrutura , Homologia de Sequência de AminoácidosRESUMO
The photoreceptor cells R8, R2, and R5 are the first cells to initiate neuronal differentiation in the Drosophila eye imaginal disc. We have shown previously that these three cells require Star gene function for proper ommatidial assembly. Due to the embryonic lethality associated with mutations in Star, we have analyzed the consequence of loss of Star function in mosaic eye imaginal discs. Presumptive R8, R2, and R5 cells that lack Star function fail to differentiate neuronally and die a few hours later. Enhancer trap insertions reveal that Star expression in the eye disc is restricted to the developing R8, R2, and R5 cells. Taken together, these data suggest that Star is required for the reception of a signal and/or the execution of a developmental program that leads to the neuronal differentiation of R8, R2, and R5. Star is also required for the formation of wing veins and is expressed in developing veins, suggesting that at least partially overlapping pathways may operate during photoreceptor cell differentiation and wing vein formation. The role of Star in cell-cell signaling is supported by the observation of genetic interactions between Star and mutations that reduce signaling through both sevenless and the Drosophila EGF-receptor homologue, including Ras1 and Son of sevenless.
Assuntos
Drosophila/genética , Genes ras , Neurônios/citologia , Retina/citologia , Animais , Morte Celular , Diferenciação Celular , Drosophila/citologia , Drosophila/embriologia , Larva , Mutação , Proteínas Tirosina Quinases/metabolismo , Transdução de Sinais , Asas de Animais/embriologiaRESUMO
We have cloned and characterized cDNAs coding for a receptor-class phosphotyrosine phosphatase gene from Drosophila melanogaster. The gene maps to the polytene chromosome bands 99A7-8. The cDNA clones code for a polypeptide of 1301 amino acids with a predicted molecular mass of 145 kDa. The extracellular domain includes two fibronectin-type III-like domains. The cytoplasmic region contains two tandemly repeated phosphotyrosine phosphatase-like domains. Residues shown crucial for catalytic activity are absent in the second domain. This Drosophila receptor-class phosphotyrosine phosphatase polypeptide is expressed on axons of the embryonic central nervous system.
Assuntos
Axônios/enzimologia , Drosophila melanogaster/genética , Proteínas Tirosina Fosfatases/genética , Receptores de Superfície Celular/genética , Sequência de Aminoácidos , Animais , Anticorpos , Sequência de Bases , Bandeamento Cromossômico , Clonagem Molecular , Sondas de DNA , Drosophila melanogaster/embriologia , Drosophila melanogaster/enzimologia , Fibronectinas/genética , Humanos , Dados de Sequência Molecular , Sistema Nervoso/enzimologia , Oligodesoxirribonucleotídeos , Reação em Cadeia da Polimerase/métodos , Proteínas Tirosina Fosfatases/isolamento & purificação , Sequências Repetitivas de Ácido Nucleico , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
Roughened is a dominant mutation of D. melanogaster that disrupts eye development. The majority of the ommatidia in the adult eye lack a single photoreceptor cell, which is most commonly the R7 cell. The Roughened mutation disrupts the early stages of photoreceptor cell determination. Roughened is a dominant gain-of-function mutation that results from a single amino acid change (Phe157 to Leu) in the Drosophila Rap1 protein. Loss of function Rap1 mutations are lethal. Drosophila Rap1 protein is 88% identical to human rap1A/K-rev1 protein, a putative antagonist of ras action.
Assuntos
Drosophila melanogaster/embriologia , Olho/embriologia , Proteínas de Ligação ao GTP/fisiologia , Sequência de Aminoácidos , Animais , Drosophila melanogaster/genética , Genes Dominantes , Dados de Sequência Molecular , Mutação , Alinhamento de Sequência , Proteínas rap de Ligação ao GTPRESUMO
The chromosome translocation forming the hybrid bcr-abl gene is thought to be the initiating event in chronic myeloid leukaemia (CML) and some cases of acute lymphoblastic leukaemia. To assess the impact of bcr-abl upon haemopoiesis, lethally irradiated mice were reconstituted with bone marrow cells enriched for cycling stem cells and infected with a bcr-abl bearing retrovirus. The mice developed several fatal diseases with abnormal accumulations of macrophage, erythroid, mast and lymphoid cells, and marked strain differences in disease distribution and kinetics. Some mice exhibited more than one neoplastic cell type and, in some instances, these were clonally related, indicating that a progenitor or stem cell had been transformed. While classical CML was not observed, the macrophage tumours were accompanied by a mild CML-like syndrome, probably due to myeloid growth factor production by tumour cells. The erythroid and mast cell diseases were rarely transplantable, in contrast to the macrophage tumours and lymphomas, but all disease types displayed limited clonality. These results establish that bcr-abl confers a proliferative advantage on diverse haemopoietic cells but complete transformation probably involves additional genetic changes.
Assuntos
Transformação Celular Neoplásica , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Neoplasias Experimentais/genética , Oncogenes , Retroviridae/genética , Transfecção , Animais , Linhagem Celular , Fatores Estimuladores de Colônias/farmacologia , DNA/genética , DNA/isolamento & purificação , Fator Estimulador de Colônias de Granulócitos e Macrófagos , Substâncias de Crescimento/farmacologia , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Células-Tronco Hematopoéticas/metabolismo , Interleucina-3/farmacologia , Linfoma/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Endogâmicos DBA , RNA/genética , RNA/isolamento & purificaçãoRESUMO
In chronic myeloid leukemia and some cases of acute lymphoblastic leukemia, a 9;22 chromosome translocation has fused most of the c-abl oncogene to a gene designated bcr. To explore in vivo the biological effects of the chimeric gene, we introduced a facsimile of the translocation product, a bcr-v-abl gene, into the mouse germ line under the control of the immunoglobulin heavy-chain enhancer or a retroviral long terminal repeat. Some transgenic mice bearing either construct developed clonal lymphoid tumors. T lymphomas predominated, but some pre-B lymphomas developed. The transgenes were expressed in the tumors but not detectably in the lymphoid tissues of nontumorous transgenic animals, implying that transcription is activated by a low-frequency somatic event. These results demonstrate that bcr-v-abl is tumorigenic in vivo and provide a new animal model for lymphomagenesis.
Assuntos
Transformação Celular Neoplásica , Linfoma/genética , Oncogenes , Animais , Linfócitos B/imunologia , Clonagem Molecular , DNA/biossíntese , DNA/genética , Feminino , Regulação da Expressão Gênica , Genes Sintéticos , Immunoblotting , Linfoma/imunologia , Linfoma/patologia , Masculino , Camundongos , Camundongos Transgênicos , Fenótipo , RNA Mensageiro/genética , Linfócitos T/imunologia , Translocação GenéticaRESUMO
Murine bone marrow cells infected with a novel recombinant retrovirus, MPZen(GM-CSF), were engrafted into lethally irradiated recipients. The transplanted animals developed extremely high circulating levels of GM-CSF (up to 3 x 10(5) units/ml), and greatly elevated peripheral nucleated cell counts (up to 110 x 10(6) per ml). Their haemopoietic tissues contained GM-CSF proviral DNA and produced substantial levels of GM-CSF. The mice died within 4 weeks of transplantation with extensive neutrophil and macrophage infiltration of the spleen, lung, liver and peritoneal cavity and significant infiltration of both heart and skeletal muscle by neutrophils, macrophages and eosinophils. The thymus and lymph nodes were deficient in lymphoid cells. No disease occurred when infected cells from haemopoietic tissues of the primary transplanted animals were injected into normal or sub-lethally irradiated mice. Dysregulated GM-CSF expression by haemopoietic cells thus produces a fatal albeit non-neoplastic myeloproliferative syndrome.