RESUMO
A new human gene has been identified on chromosome 16 in the interval containing the locus for polycystic kidney disease (PKD1) by analysis of a genomic cosmid clone and cDNAs. The gene contains at least one intron and is actively transcribed in tissues from kidney and brain. The putative gene product is predicted to be homologous to the yeast scERV1 protein by virtue of the high degree of identity (42%) over the entire length of the polypeptides. In former studies the yeast scERV1 gene was found to be essential for oxidative phosphorylation, the maintenance of mitochondrial genomes, and the cell-division cycle. In this study a yeast expression vector with a chimeric reading frame coding for the first 21 amino acids of the yeast protein and the terminal 100 amino acid residues of the human factor was transformed into yeast mutants with two different defects for scERV1. The chimeric human gene product was able to complement the yeast mutants and restored near normal viability. This identifies the human gene as a structural and functional homologue of the scERV1 gene.
Assuntos
Cromossomos Humanos Par 16 , Proteínas Fúngicas/genética , Proteínas Mitocondriais , Doenças Renais Policísticas/genética , Proteínas/genética , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Sequência de Aminoácidos , Sequência de Bases , Encéfalo/metabolismo , Mapeamento Cromossômico , Clonagem Molecular , Sequência Conservada , Cosmídeos , Primers do DNA , Proteínas Fúngicas/biossíntese , Expressão Gênica , Humanos , Rim/metabolismo , Dados de Sequência Molecular , Mutagênese , Oxirredutases atuantes sobre Doadores de Grupo Enxofre , Reação em Cadeia da Polimerase , Biossíntese de Proteínas , Mapeamento por Restrição , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos , Canais de Cátion TRPP , Transcrição GênicaRESUMO
Previous studies demonstrated that metastatic MDA-MB-435 breast carcinoma cells synthesized and secreted less of the extracellular matrix protein thrombospondin 1 (TSP1) than nonmetastatic breast carcinoma cell lines, a trend also observed for melanoma and lung carcinoma cell lines. To directly examine the effect of tumor cell TSP1 expression on tumor growth and metastasis. MDA-MB-435 cells were transfected with full length THBS-1 cDNA linked to a constitutive cytomegalovirus promoter, or with the cytomegalovirus vector alone. Injection of transfected clones that overexpressed TSP1 into the mammary fat pad of nude mice resulted in a dose-dependent inhibition of primary tumor size and an inhibition of spontaneous pulmonary metastases, which occurred in 21-30% of THBS-1 transfectants compared to 44-49% of controls (P = 0.007). An additional clone was identified that overexpressed a COOH-terminally truncated TSP1. This clone produced larger primary tumors and an increase in the occurrence of metastases relative to control transfectants, suggesting the participation of a previously understudied region of TSP1 in the regulation of tumor progression. The THBS-1 and control transfectants did not exhibit significant differences in growth, colonization, or motility in vitro. However, a relative reduction in capillary densities in primary tumors formed by the wild-type THBS-1 transfectants was observed, suggestive of an angiostatic effect. The data indicate that tumor cell production of TSP1 can exert a significant inhibitory effect on tumor progression in the MDA-MB-435 breast carcinoma cell line, which may be attributable in part to a reduction in angiogenesis.
Assuntos
Neoplasias da Mama/metabolismo , Moléculas de Adesão Celular/metabolismo , Glicoproteínas de Membrana/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Neoplasias da Mama/irrigação sanguínea , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Moléculas de Adesão Celular/genética , Divisão Celular/genética , Movimento Celular/genética , DNA Complementar/genética , Humanos , Neoplasias Pulmonares/secundário , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Nus , Microcirculação , Dados de Sequência Molecular , Neovascularização Patológica/genética , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , Trombospondinas , Transfecção , Células Tumorais CultivadasRESUMO
A novel human gene (sazD) that maps to the autosomal dominant polycystic kidney disease region shares sequence similarity with members of the beta-transducin superfamily. The cDNA sazD-c predicts an approximately 58-kDa protein (sazD) with seven internal repeats, similar to the WD-40 motif of the transducin family. The size of this protein family has been expanding rapidly; however, neither the structure nor the function of this repeated motif is known. Preliminary data do not suggest that sazD is mutated in patients with polycystic kidney disease.
