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Reactivation of apolipoprotein II gene transcription by cycloheximide reveals two steps in the deactivation of estrogen receptor-mediated transcription.
Sensel, M G; Binder, R; Lazier, C B; Williams, D L.
Afiliación
  • Sensel MG; Department of Pharmacological Sciences, State University of New York at Stony Brook 11794-8651.
Mol Cell Biol ; 14(3): 1733-42, 1994 Mar.
Article en En | MEDLINE | ID: mdl-8114707
In this report, we describe apolipoprotein II (apoII) gene expression in cell lines derived by stable expression of the chicken estrogen receptor in LMH chicken hepatoma cells. In cell lines expressing high levels of receptor (LMH/2A), apoII gene expression is increased by estrogen 300-fold compared with levels in the receptor-deficient parent LMH line. LMH/2A cells show apoII mRNA induction and turnover kinetics similar to those in chicken liver. Inhibition of protein synthesis with cycloheximide (CHX) or puromycin following estrogen withdrawal superinduces apoII mRNA without affecting apoII mRNA stability. Superinduction is due to an estrogen-independent reactivation of apoII gene transcription. The apoII gene can be reactivated by CHX for up to 24 h following hormone withdrawal, suggesting that the gene is in a repressed yet transcriptionally competent state. These results reveal two distinct events necessary for termination of estrogen receptor-mediated transcription. The first event, removal of hormone, is sufficient to stop transcription when translation is ongoing. The second event is revealed by the CHX-induced superinduction of apoII mRNA following hormone withdrawal. This superinduction suggests that deactivation of estrogen receptor-mediated transcription requires a labile protein. Furthermore, reactivation of apoII gene expression by CHX and estrogen is additive, suggesting that estrogen is unable to overcome repression completely. Thus, a labile protein may act to repress estrogen receptor-mediated transcription of the apoII gene.
Asunto(s)

Texto completo: 1 Colección: 01-internacional Banco de datos: MEDLINE Asunto principal: Apolipoproteínas / Precursores de Proteínas / Transcripción Genética / Receptores de Estrógenos / Cicloheximida Límite: Animals Idioma: En Revista: Mol Cell Biol Año: 1994 Tipo del documento: Article

Texto completo: 1 Colección: 01-internacional Banco de datos: MEDLINE Asunto principal: Apolipoproteínas / Precursores de Proteínas / Transcripción Genética / Receptores de Estrógenos / Cicloheximida Límite: Animals Idioma: En Revista: Mol Cell Biol Año: 1994 Tipo del documento: Article