SRC proximal and core promoter elements dictate TAF1 dependence and transcriptional repression by histone deacetylase inhibitors.
Histone deacetylase inhibitors (HDIs) induce cell cycle arrest, differentiation, or apoptosis in numerous cancer cell types both in vivo and in vitro. These dramatic effects are the result of a specific reprogramming of gene expression. However, the mechanism by which these agents activate the transcription of some genes, such as p21(WAF1), but repress others, such as cyclin D1, is currently unknown. We have been studying the human SRC gene as a model for HDI-mediated transcriptional repression. We found previously that both the tissue-specific and housekeeping SRC promoters were equally repressed by HDIs. Here we show that, despite an overt dissimilarity, both SRC promoters do share similar core promoter elements and transcription is TAF1 dependent. Detailed analysis of the SRC promoters suggested that both core and proximal promoter elements were responsible for HDI-mediated repression. This was confirmed in a series of promoter-swapping experiments with the HDI-inducible, TAF1-independent p21(WAF1) promoter. Remarkably, all the SRC-p21(WAF1) chimeric promoter constructs were not only repressed by HDIs but also dependent on TAF1. Together these experiments suggest that the overall promoter architecture, rather than discrete response elements, is responsible for HDI-mediated repression, and they implicate core promoter elements in particular as potential mediators of this response.
Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
Scott M
SM
Dehm
Traci L
TL
Hilton
Edith H
EH
Wang
Keith
K
Bonham
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D006224:Cricetinae; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016391:Genes, src / Q000187:drug effects; D051548:Histone Acetyltransferases; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012689:Sequence Homology, Nucleic Acid; D035381:TATA-Binding Protein Associated Factors / Q000235:genetics / Q000378:metabolism*; D035362:Transcription Factor TFIID / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D051548:Histone Acetyltransferases; C069001:TATA-binding protein associated factor 250 kDa