Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 1 de 1
Filtrar
Más filtros

Bases de datos
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
J Biol Chem ; 271(40): 24842-9, 1996 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-8798759

RESUMEN

The human epithermoid carcinoma-derived cell line MA1, established by introduction of the adenovirus E1A 12 S cDNA linked to the mouse mammary tumor virus long terminal repeat, elicits apoptosis after induction of E1A12S in response to dexamethasone. The level of topoisomerase IIalpha begins to decrease steeply within 36 h preceding the onset of DNA fragmentation, whereas its mRNA level is unchanged (Nakajima, T., Ohi, N., Arai, T., Nozaki, N., Kikuchi, A., and Oda, K. (1995) Oncogene 10, 651-662). Topoisomerase IIalpha prepared by immunoprecipitation or extraction of the nuclear matrix was degraded much more efficiently in the S10 extract prepared from MA1 cells treated with dexamethasone for 42 h (the 42-h extract) than in the extract from untreated MA1 cells (the 0-h extract) in an ATP- and ubiquitin-dependent manner. The proteolytic activity for degradation of topoisomerase IIalpha was suppressed specifically by inhibitors for the proteasome and was much reduced in the 42-h extract prepared from MA1-derivative cell lines expressing E1B19k or Bcl-2. The proteolytic activity was lost after fractionation of the 42-h S10 extract into the S70 and P70 fractions by centrifugation at 70,000 x g for 6 h but partially recovered when these fractions were combined. Polyubiquitinated forms of topoisomerase IIalpha could be detected by incubating it in the S70 or S100 extract, which lacks most of the proteasome activity. The ubiquitination activity in S70 prepared from the 42-h extract was 4- to 5-fold higher than that prepared from the 0-h extract. These results suggest that a component(s) in the ubiquitin proteolysis pathway, responsible for ubiquitination and degradation of topoisomerase IIalpha, is activated or induced during the latent phase of E1A-induced apoptosis.


Asunto(s)
Proteínas E1A de Adenovirus/genética , Apoptosis/genética , ADN-Topoisomerasas de Tipo II/metabolismo , Isoenzimas/metabolismo , Ubiquitinas/metabolismo , Adenosina Trifosfato/metabolismo , Antígenos de Neoplasias , Extractos Celulares , Cisteína Endopeptidasas/efectos de los fármacos , ADN Complementario , Proteínas de Unión al ADN , Inhibidores Enzimáticos/farmacología , Genes bcl-2 , Humanos , Hidrólisis , Complejos Multienzimáticos/efectos de los fármacos , Complejo de la Endopetidasa Proteasomal , Transfección , Células Tumorales Cultivadas
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA