Nutrient regulation of gene expression by the sterol regulatory element binding proteins: increased recruitment of gene-specific coregulatory factors and selective hyperacetylation of histone H3 in vivo.
We have evaluated the mechanism for sterol-regulated gene expression by the sterol regulatory element binding proteins (SREBPs) in intact cells. We show that activation of SREBPs by sterol depletion results in the increased binding of Sp1 to a site adjacent to SREBP in the promoter for the low density lipoprotein (LDL) receptor gene in vivo. Similarly, sterol depletion resulted in the increased recruitment of two distinct SREBP coregulatory factors, NF-Y and CREB, to the promoter for hydroxymethyl glutaryl CoA reductase, another key gene of intracellular cholesterol homeostasis. Furthermore, increased acetylation of histone H3 but not H4 was also detected in chromatin from both promoters on SREBP activation. Thus, SREBP activation results in the similar selective recruitment of different coregulatory generic transcription factors to two separate cholesterol-regulated promoters. These studies demonstrate the utility of the chromatin immunoprecipitation technique for analyzing the differential action of low-abundance transcription factors in fundamental regulatory events in intact cells. Our results also provide key in vivo support for the mechanism proposed from cell-free experiments, where SREBP increased the binding of Sp1 to the LDL receptor promoter. Finally, our findings also indicate that subtle differences in the pattern of core histone acetylation play a role in selective gene activation.
Bennett
M K
MK
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
Osborne
T F
TF
D000107:Acetylation; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D016466:CHO Cells; D006224:Cricetinae; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation; D006657:Histones / Q000378:metabolism*; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011973:Receptors, LDL / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000502:physiology; D051780:Sterol Regulatory Element Binding Protein 1; D013261:Sterols / Q000494:pharmacology; D014157:Transcription Factors; D015533:Transcriptional Activation
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D011973:Receptors, LDL; D016329:Sp1 Transcription Factor; D051780:Sterol Regulatory Element Binding Protein 1; D013261:Sterols; D014157:Transcription Factors; D004247:DNA