RESUMO
Human Tob2 is a member of the Tob/BTG1 anti-proliferative family of proteins. Here, we report the molecular cloning and characterization of the mouse tob2 gene. The tob2 gene contains an open reading frame of 345 amino acids with an 89% identity to its human counterparts. The coding region of mouse tob2 is not interrupted by introns. The tob2 transcript is 4.2kb long, the size being similar to that of the human tob2 transcript, and detected ubiquitously in various tissues of adult mice. In addition, in situ hybridization shows that tob2 is ubiquitously expressed in embryo, the level of expression being especially high in skeletal muscle. Collectively, Tob2 is suggested to play roles both during embryogenesis and in adults.
Assuntos
Proteínas de Ciclo Celular/genética , Genes/genética , Células 3T3 , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Southern Blotting , Linhagem Celular , Clonagem Molecular , DNA/química , DNA/genética , DNA/isolamento & purificação , Expressão Gênica , Humanos , Hibridização In Situ , Masculino , Camundongos , Camundongos Endogâmicos , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Distribuição TecidualRESUMO
Bone morphogenetic protein (BMP) controls osteoblast proliferation and differentiation through Smad proteins. Here we show that Tob, a member of the emerging family of antiproliferative proteins, is a negative regulator of BMP/Smad signaling in osteoblasts. Mice carrying a targeted deletion of the tob gene have a greater bone mass resulting from increased numbers of osteoblasts. Orthotopic bone formation in response to BMP2 is elevated in tob-deficient mice. Overproduction of Tob represses BMP2-induced, Smad-mediated transcriptional activation. Finally, Tob associates with receptor-regulated Smads (Smad1, 5, and 8) and colocalizes with these Smads in the nuclear bodies upon BMP2 stimulation. The results indicate that Tob negatively regulates osteoblast proliferation and differentiation by suppressing the activity of the receptor-regulated Smad proteins.
Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Ligação a DNA/metabolismo , Osteoblastos/fisiologia , Transdução de Sinais/fisiologia , Transativadores/metabolismo , Fator de Crescimento Transformador beta , Alelos , Animais , Proteína Morfogenética Óssea 2 , Proteína Morfogenética Óssea 7 , Remodelação Óssea/fisiologia , Diferenciação Celular/fisiologia , Divisão Celular/fisiologia , Tamanho Celular/fisiologia , Expressão Gênica/fisiologia , Mutação em Linhagem Germinativa/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular , Ligantes , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Osteoblastos/citologia , Fosfoproteínas/metabolismo , Crânio/citologia , Proteínas Smad , Proteína Smad1 , Proteína Smad5 , Proteína Smad8 , Transcrição Gênica/fisiologiaRESUMO
Human cDNAs encoding a novel member of Tob/BTG1 anti-proliferative family proteins were cloned. The putative protein product termed Tob2 consisted of 344 amino acids with high similarity to the Tob protein. The tob2 mRNA was 4.1 kb long and was ubiquitously expressed in human adult tissues, as was revealed by Northern blot hybridization. However, further in situ hybridization analysis showed a characteristic expression of the tob2 mRNA in oocytes, suggesting a unique role of Tob2 in oogenesis. Like the Tob protein, Tob2 inhibited cell cycle progression from the G0/G1 to S phases. Intriguingly, the amino-terminal half of Tob2 as well as that of Tob was associated with a human homologue of yeast Caf1, a component of the CCR4 transcription factor complex. Moreover, Caf1 was associated with cyclin dependent kinases. These data suggested that both Tob and Tob2 were involved in cell cycle regulation through their interaction with Caf1. Finally, the tob2 gene was mapped to human chromosome 22q13.1-q13.31.
Assuntos
Quinases relacionadas a CDC2 e CDC28 , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Quinases Ciclina-Dependentes/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas , Proteínas Proto-Oncogênicas , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor , Células 3T3/citologia , Células 3T3/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/metabolismo , Linhagem Celular , Clonagem Molecular , Quinase 2 Dependente de Ciclina , Quinase 4 Dependente de Ciclina , Exorribonucleases , Fase G1/genética , Perfilação da Expressão Gênica , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Proteínas de Neoplasias/genética , Proteínas Serina-Treonina Quinases/metabolismo , Coelhos , Proteínas Repressoras , Ribonucleases , Homologia de Sequência de Aminoácidos , Frações Subcelulares , Fatores de Transcrição/genéticaRESUMO
Using a polymerase chain reaction-mediated cloning procedure, we have identified a novel member, termed ANA (from Abundant in Neuroepithelium Area), of Tob/BTG1 family of antiproliferative genes. Molecular cloning and analysis of cDNAs revealed that the human and mouse ANA encoded a protein of 252 amino acids. The amino-terminal half of ANA was homologous to the previously characterized antiproliferative gene products, BTG1, PC3/TIS21/BTG2, and Tob. The human ANA gene was localized at chromosome 21q11.2-q21.1. ANA was expressed in a variety of tissues and cell lines, its expression being high in the ovary, testis, prostate, thymus, and lung. Further analysis revealed that ANA expression was high in the ventricular zone of the developing central nervous system. Finally, overexpression of ANA impaired serum-induced cell cycle progression from the G0/G1 to S phase. In conclusion, ANA is a fourth member of the Tob/BTG1 family that might play roles in neurogenesis in the central nervous system.
Assuntos
Proteínas de Drosophila , Glicoproteínas/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Supressoras de Tumor , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/genética , Ciclo Celular , Divisão Celular/efeitos dos fármacos , Mapeamento Cromossômico , Cromossomos Humanos Par 21 , Clonagem Molecular , Humanos , Camundongos , Dados de Sequência Molecular , Proteínas de Neoplasias/genética , Reação em Cadeia da Polimerase , Distribuição TecidualRESUMO
Inflammatory cytokines such as tumor necrosis factor alpha (TNF alpha), interferon gamma (IFN gamma) and interleukin-1 beta (IL-1 beta) play important roles in the mechanisms of hepatitis. The effects of these cytokines on the expression of vascular cell adhesion molecule-1 (VCAM-1) in hepatocytes were examined. TNF alpha and IL-1 beta but not IFN gamma or IL-6 induced VCAM-1 expression on primary cultured murine hepatocytes in a dose- and a time-dependent fashion. TNF alpha is significantly more effective than IL-1 beta on the induction of VCAM-1 expression. The results of RT-PCR demonstrate that these cytokines regulate VCAM-1 expression at mRNA level. These results suggest that TNF alpha and IL-1 beta participate in the pathogenesis of hepatitis via induction of VCAM-1 molecules on hepatocytes.