Selective association of sterol regulatory element-binding protein isoforms with target promoters in vivo

Mary K. Bennett, Julia I. Toth, Timothy Osborne

Research output: Contribution to journalArticle

Abstract

The mRNAs for all three members of the sterol regulatory element-binding protein (SREBP) family are widely expressed, and the proteins are highly similar. They have potential to both hetero- and homodimerize through their bHLHLZ domains, so it has been difficult to definitively study the role of each one apart from the other two. In the current study, we have utilized cell lines that express only one functional SREBP and the chromatin immunoprecipitation technique to analyze individual SREBP binding to three specific target genes: hydroxymethylglutaryl-CoA reeducate (Red), fatty acid synthase (FAS), and squalene synthase (SQS). Our studies show that SREBP-2 binds to promoters for all three genes, and in agreement with the original report using these cells, all three mRNAs are also induced. In the line expressing only SREBP-1a, mRNAs for Red and FAS are induced, but SQS is not. Chromatin immunoprecipitation also shows that SREBP-1a is recruited efficiently to Red and FAS promoters but not to SQS. This observation indicates SREBP-2 selectively binds the SQS promoter and is sufficient to explain the lack of SQS mRNA induction in the SREBP-1a-expressing cells. SREBP-1c protein was not stably recruited to any SREBP target promoter despite being fully active in DNA binding when purified from extracts of the corresponding cells. This is also sufficient to explain the lack of SREBP target gene induction by the singular expression of SREBP-1c. We also show that whereas SREBP-1a and -2 proteins interact efficiently with transcriptional co-activators that modify cellular chromatin, SREBP-1c does not. Taken together, our data support a model suggesting that chromatin modification is required during the initial stage of specific site recognition by SREBPs in native chromatin in vivo.

Original languageEnglish (US)
Pages (from-to)37360-37367
Number of pages8
JournalJournal of Biological Chemistry
Volume279
Issue number36
DOIs
StatePublished - Sep 3 2004
Externally publishedYes

Fingerprint

Sterol Regulatory Element Binding Proteins
Sterol Regulatory Element Binding Protein 1
Farnesyl-Diphosphate Farnesyltransferase
Protein Isoforms
Sterol Regulatory Element Binding Protein 2
Chromatin
Fatty Acid Synthases
Messenger RNA
Genes
Chromatin Immunoprecipitation
Proteins
Cell Extracts
Protein Binding
Cells
Cell Line
DNA

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Selective association of sterol regulatory element-binding protein isoforms with target promoters in vivo. / Bennett, Mary K.; Toth, Julia I.; Osborne, Timothy.

In: Journal of Biological Chemistry, Vol. 279, No. 36, 03.09.2004, p. 37360-37367.

Research output: Contribution to journalArticle

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