HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: M600476-JLR200v1 48/2/318    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lee, P. C. W. Articles by DeBose-Boyd, R. A. Search for Related Content PubMed PubMed Citation Articles by Lee, P. C. W. Articles by DeBose-Boyd, R. A. Social Bookmarking                      What's this?

Journal of Lipid Research, Vol. 48, 318-327, February 2007
Copyright © 2007 by American Society for Biochemistry and Molecular Biology

Mutations within the membrane domain of HMG-CoA reductase confer resistance to sterol-accelerated degradation

Peter C. W. Lee, Andrew D. Nguyen and Russell A. DeBose-Boyd¹

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046

Published, JLR Papers in Press, November 7, 2006.

¹ To whom correspondence should be addressed. e-mail: russell.debose-boyd{at}utsouthwestern.edu

The pivotal event for sterol-induced degradation of the cholesterol biosynthetic enzyme HMG-CoA reductase is binding of its membrane domain to Insig proteins in the endoplasmic reticulum. Insigs are carriers for gp78, an E3 ubiquitin ligase that marks reductase for proteasomal degradation. We report here the isolation of mutant Chinese hamster ovary cell lines, designated SRD-16, -17, and -18, in which sterol-induced ubiquitination and degradation of reductase are severely impaired. These cells were produced by chemical mutagenesis and selection with SR-12813, a compound that mimics sterols in stimulating ubiquitination and degradation of reductase. Each SRD cell line was found to contain a point mutation in one reductase allele, resulting in substitutions of aspartate for serine-60 (SRD-16), arginine for glycine-87 (SRD-17), and proline for alanine-333 (SRD-18). Sterols failed to promote ubiquitination and degradation of these reductase mutants, owing to their decreased affinity for Insigs. Thus, three different point mutations in reductase, all of which localize to the membrane domain, disrupt Insig binding and abolish sterol-accelerated degradation of the enzyme.

Supplementary key words cholesterol homeostasis • endoplasmic reticulum-associated degradation • ubiquitination • somatic cell genetics • mutagenesis • membrane attachment region • 3-hydroxy-3-methylglutaryl coenzyme A reductase

Abbreviations: CHO, Chinese hamster ovary; CMV, cytomegalovirus; EMS, ethylmethane sulfonate; ER, endoplasmic reticulum; 25-HC, 25-hydroxycholesterol; LPDS, lipoprotein-deficient serum; SCAP, sterol-regulatory element binding protein cleavage-activating protein; SREBP, sterol-regulatory element binding protein

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				P. C. W. Lee and R. A. DeBose-Boyd Intramembrane glycine mediates multimerization of Insig-2, a requirement for sterol regulation in Chinese hamster ovary cells J. Lipid Res., January 1, 2010; 51(1): 192 - 201. [Abstract] [Full Text] [PDF]

				A. D. Nguyen, S. H. Lee, and R. A. DeBose-Boyd Insig-mediated, Sterol-accelerated Degradation of the Membrane Domain of Hamster 3-Hydroxy-3-methylglutaryl-coenzyme A Reductase in Insect Cells J. Biol. Chem., September 25, 2009; 284(39): 26778 - 26788. [Abstract] [Full Text] [PDF]

				A. D. Nguyen, J. G. McDonald, R. K. Bruick, and R. A. DeBose-Boyd Hypoxia Stimulates Degradation of 3-Hydroxy-3-methylglutaryl-coenzyme A Reductase through Accumulation of Lanosterol and Hypoxia-Inducible Factor-mediated Induction of Insigs J. Biol. Chem., September 14, 2007; 282(37): 27436 - 27446. [Abstract] [Full Text] [PDF]

				P. C. W. Lee, P. Liu, W.-P. Li, and R. A. DeBose-Boyd Amplification of the gene for SCAP, coupled with Insig-1 deficiency, confers sterol resistance in mutant Chinese hamster ovary cells J. Lipid Res., September 1, 2007; 48(9): 1944 - 1954. [Abstract] [Full Text] [PDF]