Assuntos
Acondroplasia/tratamento farmacológico , Acondroplasia/patologia , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/deficiência , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/genética , Displasia Tanatofórica/tratamento farmacológico , Displasia Tanatofórica/patologia , Animais , Feminino , MasculinoRESUMO
Mutations in the ATRX gene are associated with an X-linked mental retardation (XLMR) syndrome most often accompanied by alpha-thalassaemia (ATR-X syndrome). The ATRX gene encodes a predicted protein of 280 kDa featuring a PHD zinc finger motif and an ATPase/helicase domain of the SWI/SNF type; the vast majority of mutations in the ATRX gene fall within these two motifs. Although these domains are suggestive of a role for ATRX in transcriptional regulation by affecting chromatin structure and/or function, the precise cellular role of the ATRX protein remains undefined. Using indirect immunofluorescence and biochemical fractionation, we demonstrate that the ATRX protein has a punctate nuclear staining pattern and that it is tightly associated with the nuclear matrix at interphase. At the onset of M phase, the ATRX protein was associated mainly with condensed chromatin. The association of the ATRX protein with chromosomes at mitosis is concomitant with phosphorylation of the protein and its association with heterochromatin protein 1alpha (HP1alpha). The phosphorylation-dependent changes in localization between the nuclear matrix and condensed chromatin are consistent with a dual role for ATRX, possibly involving gene regulation at interphase and chromosomal segregation at mitosis.
Assuntos
Ciclo Celular/genética , Cromatina/metabolismo , DNA Helicases , Proteínas de Ligação a DNA/metabolismo , Matriz Nuclear/metabolismo , Proteínas Nucleares , Fatores de Transcrição/metabolismo , Animais , Células COS , Cromatina/genética , Homólogo 5 da Proteína Cromobox , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/genética , Células HeLa , Humanos , Interfase/genética , Mitose/genética , Matriz Nuclear/genética , Fosforilação , Testes de Precipitina , Fatores de Transcrição/genética , Proteína Nuclear Ligada ao XRESUMO
We have isolated and characterized a novel cDNA, C1q-Related Factor (CRF), that is predicted to encode a 258 amino acid polypeptide with a hydrophobic signal sequence, a collagenous region, and a globular domain at the carboxy terminus that shares homology to the C1q signature domain. Human CRF transcript is expressed at highest levels in the brain, particularly in the brainstem. In situ hybridization to mouse brain sections demonstrated that CRF transcripts are most abundant in areas of the nervous system involved in motor function, such as the Purkinje cells of the cerebellum, the accessory olivary nucleus, the pons and the red nucleus. The mouse CRF homolog is highly similar to the human gene at both the nucleotide and protein level, suggesting an important conserved role for this protein.
Assuntos
Química Encefálica/fisiologia , Ativação do Complemento , Complemento C1q/isolamento & purificação , Atividade Motora/fisiologia , Sequência de Aminoácidos , Animais , Clonagem Molecular , Humanos , Camundongos , Dados de Sequência Molecular , Biossíntese de Proteínas , RNA/biossíntese , Homologia de Sequência de AminoácidosRESUMO
Based on the dominance of cellular senescence over immortality, immortal human cell lines have been assigned to four complementation groups for indefinite division. Human chromosomes carrying senescence genes have been identified, including chromosome 4. We report the cloning and identification of a gene, mortality factor 4 (MORF 4), which induces a senescent-like phenotype in immortal cell lines assigned to complementation group B with concomitant changes in two markers for senescence. MORF 4 is a member of a novel family of genes with transcription factor-like motifs. We present here the sequences of the seven family members, their chromosomal locations, and a partial characterization of the three members that are expressed. Elucidation of the mechanism of action of these genes should enhance our understanding of growth regulation and cellular aging.
Assuntos
Senescência Celular/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Sequência de Bases , Divisão Celular/genética , Linhagem Celular , Núcleo Celular/metabolismo , Expressão Gênica , Teste de Complementação Genética , Humanos , Dados de Sequência Molecular , Família Multigênica , Sondas de Oligonucleotídeos/genética , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/metabolismoRESUMO
We have constructed a panel of human x murine microcell hybrids containing individual human chromosomes tagged with a dual selectable marker conferring hygromycin B resistance and ganciclovir sensitivity. Over 500 independent microcell hybrids (B78MC) were generated and more than 200 individually isolated. We have identified the human chromosome content of several B78MC hybrids and verified that the majority are responsive to positive and negative selection. Once fully characterized, this panel will be useful in the study of dominant regulators of gene activity, such as tissue specific regulators and tumor suppressor genes.
Assuntos
Cromossomos Humanos , Cinamatos , Células Híbridas , Animais , Linhagem Celular , Técnicas de Cultura/métodos , Fibroblastos/citologia , Ganciclovir/toxicidade , Marcadores Genéticos , Herpesvirus Humano 1/genética , Humanos , Higromicina B/análogos & derivados , Higromicina B/farmacologia , Hibridização in Situ Fluorescente , Masculino , Melanoma Experimental , Camundongos , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Sitios de Sequências Rotuladas , Pele/citologia , Timidina Quinase/genéticaRESUMO
The introduction of normal chromosomes into tumor cells by microcell fusion-mediated transfer is a powerful technique to identify putative tumor suppressor genes. We have used this approach to independently transfer human chromosomes 3 and 12 into a human prostate cancer cell line, DU 145. We showed that while the extra copy of chromosome 3 had no effect on the in vivo tumorigenicity of these cells, microcell hybrids containing an introduced portion of chromosome 12 (12pter-12q13) exhibited complete suppression of tumorigenicity in athymic nude mice. The presence of a dual selectable marker facilitated the selection for cells having segregated del(12)(q13). Loss of this fragment in three different clones led to reexpression of the malignant phenotype. These results demonstrate that one or more genes on human chromosome 12 function as tumor suppressors of prostate carcinogenesis.