Cholesterol and 25-hydroxycholesterol inhibit activation of SREBPs by different mechanisms, both involving SCAP and Insigs

Christopher M Adams; Julian Reitz; Jef K De Brabander; Jamison D Feramisco; Lu Li; Michael S Brown; Joseph L Goldstein

doi:10.1074/jbc.M410302200

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Cholesterol and 25-hydroxycholesterol inhibit activation of SREBPs by different mechanisms, both involving SCAP and Insigs

Journal article

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Cholesterol and 25-hydroxycholesterol inhibit activation of SREBPs by different mechanisms, both involving SCAP and Insigs

Christopher M Adams, Julian Reitz, Jef K De Brabander, Jamison D Feramisco, Lu Li, Michael S Brown and Joseph L Goldstein

The Journal of biological chemistry, Vol.279(50), pp.52772-52780

12/10/2004

DOI: 10.1074/jbc.M410302200

PMID: 15452130

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Abstract

The current paper demonstrates that cholesterol and its hydroxylated derivative, 25-hydroxycholesterol (25-HC), inhibit cholesterol synthesis by two different mechanisms, both involving the proteins that control sterol regulatory element-binding proteins (SREBPs), membrane-bound transcription factors that activate genes encoding enzymes of lipid synthesis. Using methyl-beta-cyclodextrin as a delivery vehicle, we show that cholesterol enters cultured Chinese hamster ovary cells and elicits a conformational change in SREBP cleavage-activating protein (SCAP), as revealed by the appearance of a new fragment in tryptic digests. This change causes SCAP to bind to Insigs, which are endoplasmic reticulum retention proteins that abrogate movement of the SCAP.SREBP complex to the Golgi apparatus where SREBPs are normally processed to their active forms. Direct binding of cholesterol to SCAP in intact cells was demonstrated by showing that a photoactivated derivative of cholesterol cross-links to the membrane domain of SCAP. The inhibitory actions of cholesterol do not require the isooctyl side chain or the Delta5-double bond of cholesterol, but they do require the 3beta-hydroxyl group. 25-HC is more potent than cholesterol in eliciting SCAP binding to Insigs, but 25-HC does not cause a detectable conformational change in SCAP. Moreover, a photoactivated derivative of 25-HC does not cross-link to SCAP. These data imply that cholesterol interacts with SCAP directly by inducing it to bind to Insigs, whereas 25-HC works indirectly through a putative 25-HC sensor protein that elicits SCAP-Insig binding.

CCAAT-Enhancer-Binding Proteins - metabolism

Recombinant Proteins - metabolism

RNA, Small Interfering - genetics

Cricetinae

Membrane Proteins - genetics

Humans

Intracellular Signaling Peptides and Proteins

Recombinant Proteins - genetics

Transcription Factors - genetics

Cholesterol - metabolism

DNA-Binding Proteins - genetics

DNA-Binding Proteins - metabolism

Transcription Factors - metabolism

Animals

Membrane Proteins - chemistry

Base Sequence

Hydroxycholesterols - metabolism

Membrane Proteins - metabolism

CCAAT-Enhancer-Binding Proteins - genetics

Sterol Regulatory Element Binding Protein 1

Sterol Regulatory Element Binding Protein 2

CHO Cells

Details

Title: Subtitle: Cholesterol and 25-hydroxycholesterol inhibit activation of SREBPs by different mechanisms, both involving SCAP and Insigs
Creators: Christopher M Adams - Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046, USA
Julian Reitz
Jef K De Brabander
Jamison D Feramisco
Lu Li
Michael S Brown
Joseph L Goldstein
Resource Type: Journal article
Publication Details: The Journal of biological chemistry, Vol.279(50), pp.52772-52780
DOI: 10.1074/jbc.M410302200
PMID: 15452130
NLM abbreviation: J Biol Chem
ISSN: 0021-9258
eISSN: 1083-351X
Publisher: United States
Grant note: GM-08014 / NIGMS NIH HHS HL20948 / NHLBI NIH HHS
Language: English
Date published: 12/10/2004
Academic Unit: Molecular Physiology and Biophysics; Internal Medicine
Record Identifier: 9984025435002771

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