RESUMO
Genetic lesions in the p53 tumor suppressor gene are the most frequently observed alterations in human cancers. Typically in tumors, one allele of the p53 gene is initially mutated, followed by deletion of the remaining wildtype allele. In human colon cancer, for example, approximately 70% of late stage tumors are hemizygous mutant p53. Since the precise gene environment surrounding the p53 gene is not known, the neighboring genes concomitantly lost with wildtype p53 deletion remain undetermined. A restriction enzyme map and clone array of 1.1 Mb surrounding the p53 gene were constructed using a combination of YAC, BAC, NotI linking, and NotI jumping clones. The resulting physical map and clone array include approximately 400 kb telomeric and 700 kb centromeric to the p53 gene. Sequence determination and analysis adjacent to NotI and AscI sites, indicative of CpG islands, allowed the rapid identification of numerous genes within the cloned region. Twenty-seven transcription units were identified, including 18 characterized genes. Limited analysis of primary human colon tumors, hemizygous for the p53 gene, indicates loss of the entire 1.1-Mb region upon deletion of wildtype p53.
Assuntos
Cromossomos Humanos Par 17 , Genes p53 , Cromossomos Artificiais de Levedura , Neoplasias do Colo/genética , Ilhas de CpG , Análise Mutacional de DNA , Etiquetas de Sequências Expressas , Humanos , Repetições de Microssatélites , Dados de Sequência Molecular , Mapeamento por Restrição , Deleção de Sequência , Transcrição GênicaRESUMO
PCR can be used at different levels in oncology as many examples illustrate. Interchromosomal translocations that can be detected by PCR are very specifically found i.e. in follicular lymphomas. In the context of follow-up controls this may reduce recurrencies. By the identification of genetic lesions of an oncogene, aggressivity of a tumor may be estimated. PCR allows rapid analysis of such lesions. Analysing deletions of tumor suppressor-genes gains increasing importance in oncology. By amplification of microsatellites, presence of such a deletion may be detected. This analysis is not only important for studies of sporadic tumors but may also indicate in individual cases if the patient carries a predisposition for a certain tumor.
Assuntos
Neoplasias/genética , Reação em Cadeia da Polimerase , Sequência de Bases , Deleção de Genes , Genes Supressores de Tumor/genética , Humanos , Linfoma Folicular/genética , Dados de Sequência Molecular , Translocação GenéticaRESUMO
To study the tissue specificity of mouse mammary tumor virus (MMTV) gene expression, we developed two series of transgenic mice, containing the MMTV proviral DNA of mammary (GR) and kidney (C3H-K) origin. The expression pattern in the MMTV(GR) transgenic mice is very similar to that observed in infected animals, e.g., a strong preference for viral expression in the lactating mammary glands and lower levels of expression in salivary glands, lymphoid tissues, and male reproductive organs. One line of transgenic mice carrying the C3H-K provirus has a similar expression pattern, indicating that MMTV(C3H-K), despite a striking alteration in the U3 region of its long terminal repeat, can be expressed in the same tissues as the wild-type MMTV.
Assuntos
Regulação Viral da Expressão Gênica , Vírus do Tumor Mamário do Camundongo/genética , Provírus/genética , Animais , Feminino , Masculino , Vírus do Tumor Mamário do Camundongo/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Hibridização de Ácido Nucleico , Especificidade de ÓrgãosRESUMO
A glucocorticoid-responsive vector is described which allows for the highly inducible expression of complementary DNAs (cDNAs) in stably transfected mammalian cell lines. This vector, pLK-neo, composed of a variant mouse mammary tumor virus long terminal repeat promoter, containing a hormone regulatory element, a Geneticin resistance-encoding gene in a simian virus 40 transcription unit, and a polylinker insertion site for heterologous cDNAs, was used to express the polymeric immunoglobulin (poly-Ig) receptor and the thymocyte marker, Thy-1, in Madin-Darby canine kidney (MDCK) cells and in murine fibroblast L cells. A high level of poly-Ig receptor or Thy-1 mRNA accumulation was observed in MDCK cells in response to dexamethasone with a parallel ten- to 200-fold increase in protein synthesis depending on the recombinant protein and the transfected cell clone.
Assuntos
Dexametasona/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Vetores Genéticos/genética , Vírus do Tumor Mamário do Camundongo/genética , Sequências Repetitivas de Ácido Nucleico/genética , Animais , Antígenos de Superfície/genética , Linhagem Celular , Glicoproteínas de Membrana/genética , Camundongos , Plasmídeos/genética , Regiões Promotoras Genéticas/genética , Proteínas Recombinantes/genética , Componente Secretório/genética , Antígenos Thy-1 , Transfecção/genéticaRESUMO
Autoreactive T lymphocytes are clonally deleted during maturation in the thymus. Deletion of T cells expressing particular receptor V beta elements is controlled by poorly defined autosomal dominant genes. A gene has now been identified by expression of transgenes in mice which causes deletion of V beta 14+ T cells. The gene lies in the open reading frame of the long terminal repeat of the mouse mammary tumour virus.