RESUMEN
Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate, and pancreatic cancer. In general, carriers are defined as individuals with protein truncating mutations within the BRCA2 gene. Many Brca2 knockout lines have been produced and characterized in the mouse. We previously produced a rat Brca2 knockout strain in which there is a nonsense mutation in exon 11 between BRC repeats 2 and 3, and a truncated protein is produced. Interestingly, while such a mutation in homozygous mice would lead to limited survival of approximately 3 months, the Brca2-/- rats are 100% viable and the vast majority live to over 1 year of age. Brca2-/- rats show a phenotype of growth inhibition and sterility in both sexes. Aspermatogenesis in the Brca2-/- rats is due to a failure of homologous chromosome synapsis. Long-term phenotypes include underdeveloped mammary glands, cataract formation and lifespan shortening due to the development of tumors and cancers in multiple organs. The establishment of the rat Brca2 knockout model provides a means to study the role of Brca2 in increasing cancer susceptibility and inducing a novel ocular phenotype not previously associated with this gene.
Asunto(s)
Genes BRCA2 , Neoplasias Mamarias Experimentales/genética , Animales , Animales Modificados Genéticamente , Secuencia de Bases , Cartilla de ADN , Modelos Animales de Enfermedad , Femenino , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
Overlapping cDNA clones containing mRNA for a putative Lon protease (LonHS) were isolated from cDNA libraries prepared from human brain poly(A)+ RNA. The determined nucleotide sequence contains a 2814-bp open reading frame with two potential initiation codons (positions 62-64 and 338-340). The 5'-terminal 337-nucleotide fragment of LonHS mRNA is highly enriched with G and C nucleotides and could direct synthesis of the LonHS N-terminal domain. More likely this region promotes initiation of protein synthesis from the second AUG codon in a cap-independent manner. The amino acid sequence initiated at the second AUG codon includes 845 residues, over 30% of which are identical to those of eubacterial Lon proteases. Residues of the 'A' and 'B' motifs of NTP-binding pattern and a plausible catalytic serine residue are conserved in LonHS. Northern blot analysis revealed LonHS mRNA in lung, duodenum, liver and heart, but not in thymus cells.
Asunto(s)
Encéfalo/enzimología , Proteínas de Escherichia coli , Proteínas de Choque Térmico/genética , Proteasa La , Serina Endopeptidasas/genética , Proteasas ATP-Dependientes , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN Complementario , Escherichia coli/enzimología , Humanos , Datos de Secuencia Molecular , Ratas , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Distribución TisularRESUMEN
Bovine brain cDNA cloned earlier and attributed to calmodulin-independent adenylate cyclase encodes the neural cell adhesion molecule (N-CAM). The expression of N-CAM mRNA in Xenopus laevis oocytes increases their basal adenylate cyclase activity. Polyclonal antibodies against synthetic peptide A, VAENQQGKSKAAHFV (664-678 amino acid residues of bovine N-CAM), containing sequence AXXXXGKS which is homologous to the nucleotide-binding consensus sequence GXXXXGKS, inhibit the adenylate cyclase activity. A close relationship appears to exist between adenylate cyclase and N-CAM.
Asunto(s)
Adenilil Ciclasas/genética , Moléculas de Adhesión Celular Neuronal/genética , Secuencia de Aminoácidos , Animales , Bovinos , Clonación Molecular , Humanos , Datos de Secuencia Molecular , Homología de Secuencia de Ácido Nucleico , Xenopus laevisRESUMEN
An individual catalytic component of calmodulin-independent adenylate cyclase has been isolated from bovine brain cortex. Affinity chromatography on an immunosorbent was used. The amino acid sequence of adenylate cyclase as well as the corresponding nucleotide sequence of the cDNA has been determined. cDNA of adenylate cyclase encodes a protein consisting of 834 amino acid residues and the signal peptide (19 amino acid residues). A series of adenylate cyclase isoforms has been found. A homology between adenylate cyclases from bovine brain, E. coli and Bordetella pertussis has been revealed.