Three mutations in sterol-sensing domain of SCAP block interaction with insig and render SREBP cleavage insensitive to sterols

Daisuke Yabe; Zong-Ping Xia; Christopher M Adams; Robert B Rawson

doi:10.1073/pnas.262669399

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Three mutations in sterol-sensing domain of SCAP block interaction with insig and render SREBP cleavage insensitive to sterols

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Three mutations in sterol-sensing domain of SCAP block interaction with insig and render SREBP cleavage insensitive to sterols

Daisuke Yabe, Zong-Ping Xia, Christopher M Adams and Robert B Rawson

Proceedings of the National Academy of Sciences - PNAS, Vol.99(26), pp.16672-16677

12/24/2002

DOI: 10.1073/pnas.262669399

PMCID: PMC139202

PMID: 12482938

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Abstract

We report the isolation and characterization of a new line of mutant Chinese hamster ovary cells, designated SRD-5, that are resistant to 25HC, a potent suppressor of cleavage of sterol regulatory element-binding proteins (SREBPs) in mammalian cells. In SRD-5 cells, SREBPs are cleaved constitutively, generating transcriptionally active nuclear SREBP even in the presence of sterols. Sequence analysis of SREBP cleavage-activating protein (SCAP) transcripts from SRD-5 cells revealed the presence of a mutation in one SCAP allele that results in substitution of a conserved Leu by Phe at amino acid 315 within the sterol-sensing domain. Sterols fail to inhibit the packaging of SREBP/SCAP(L315F) complexes into budding vesicles in vitro . Sterols also fail to induce binding of SCAP(L315F) to insig-1 or insig-2, two proteins that function in the sterol-mediated retention of SREBP/SCAP complexes in the endoplasmic reticulum. Similar findings were observed for SCAP(D443N) and SCAP(Y298C), both of which cause a sterol-resistant phenotype. Thus, three different point mutations, each within the sterol-sensing domain of SCAP, prevent sterol-induced binding of SCAP to insig proteins and abolish feedback regulation of SREBP processing by sterols.

Biological Sciences

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Title: Subtitle: Three mutations in sterol-sensing domain of SCAP block interaction with insig and render SREBP cleavage insensitive to sterols
Creators: Daisuke Yabe - Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
Zong-Ping Xia - Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
Christopher M Adams - Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
Robert B Rawson - Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
Resource Type: Journal article
Publication Details: Proceedings of the National Academy of Sciences - PNAS, Vol.99(26), pp.16672-16677
DOI: 10.1073/pnas.262669399
PMID: 12482938
PMCID: PMC139202
NLM abbreviation: Proc Natl Acad Sci U S A
ISSN: 0027-8424
eISSN: 1091-6490
Publisher: National Academy of Sciences
Language: English
Date published: 12/24/2002
Academic Unit: Molecular Physiology and Biophysics; Internal Medicine
Record Identifier: 9984025318902771

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