A 47-amino-acid fragment of SV40 T antigen represses transcription from human GSTα promoters

Lauren Sompayrac, Stephen Jane, Michael Lörper, Helmut Sies

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Abstract

SV40 T antigen downregulates the expression of an important detoxitication enzyme, glutathione S-transferase α (GSTα). We show here that the target of this repression is a 14-bp element common to the human GSTA1 and GSTA2 promoters. This element, which we have named TAGR, is also critical for high-level, constitutive expression from these promoters. The TAGR element does not appear to contain a binding site for any transcription factor known to be present in fibroblasts, although the TAGR element does resemble the binding site for the Ikaros transcription factor found in hematopoietic cells. We also have identified a 47-amino-acid fragment of T antigen that includes amino acids 83-100 and 119-147, which is sufficient to repress transcription from the GSTα promoter in transient transcription assays. Thus, GSTα repression does not require binding of T antigen to pRb, p300, or p53, since the domains of T antigen required for binding these cellular proteins are missing from this T antigen fragment. We show, however, that this fragment does bind to three cellular proteins with approximate molecular weights of 54, 59, and 94 kDa.

Original languageEnglish
Pages (from-to)275-285
Number of pages11
JournalVirology
Volume249
Issue number2
DOIs
Publication statusPublished - 30 Sep 1998
Externally publishedYes

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