KLF11-mediated repression antagonizes Sp1/sterol-responsive element-binding protein-induced transcriptional activation of caveolin-1 in response to cholesterol signaling

J Biol Chem. 2005 Jan 21;280(3):1901-10. doi: 10.1074/jbc.M407941200. Epub 2004 Nov 5.

Abstract

Cholesterol is a potent regulator of gene expression via a canonical pathway co-regulated by SREBP and Sp1. Here we establish the caveolin-1 gene promoter as a cell type-specific model for SREBP/Sp1 regulation whereby lipoprotein cholesterol depletion activates caveolin-1 transcription in endothelial type cells, but not in fibroblasts, both in vitro and in vivo. By extending this model, we describe a novel pathway distinct from the prototypical SREBP/Sp1 regulatory loop involving the Sp1-like protein, KLF11. Through a combination of RNA interference, chromatin immunoprecipitation assays, electrophoretic mobility shift assays, and reporter assays, we demonstrate that in the presence of cholesterol, KLF11 acts as a dominant repressor of the caveolin-1 gene. Mechanistically, cholesterol depletion results in displacement of KLF11 from an Sp1 site flanking an SRE, indicating that activation by SREBP/Sp1 requires antagonism of KLF11 repression. The displacement of KLF11 results from both a down-regulation of its expression and competition by Sp1 for DNA binding. Therefore, these studies identify a novel pathway whereby KLF11 repression is coordinated with Sp1/SREBP activation of cholesterol-dependent gene expression in a cell type-specific manner and outline the mechanisms by which these functions are achieved.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins
  • Base Sequence
  • Cattle
  • Caveolin 1
  • Caveolins / physiology*
  • Cell Cycle Proteins / physiology*
  • Cell Line
  • Cholesterol / metabolism*
  • Chromatography, Thin Layer
  • DNA Primers
  • Electrophoretic Mobility Shift Assay
  • Humans
  • Immunoprecipitation
  • Repressor Proteins / physiology*
  • Signal Transduction*
  • Sp1 Transcription Factor / physiology*
  • Transcription Factors / antagonists & inhibitors*
  • Transcriptional Activation / physiology*

Substances

  • Apoptosis Regulatory Proteins
  • CAV1 protein, human
  • Caveolin 1
  • Caveolins
  • Cell Cycle Proteins
  • DNA Primers
  • KLF11 protein, human
  • Repressor Proteins
  • Sp1 Transcription Factor
  • Transcription Factors
  • Cholesterol