title: Sterol-induced dislocation of 3-hydroxy-3-methylglutaryl coenzyme A reductase from endoplasmic reticulum membranes into the cytosol through a subcellular compartment resembling lipid droplets.
abstract: Sterol-induced binding to Insigs in the endoplasmic reticulum (ER) allows for ubiquitination of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. This ubiquitination marks reductase for recognition by the ATPase VCP/p97, which mediates extraction and delivery of reductase from ER membranes to cytosolic 26 S proteasomes for degradation. Here, we report that reductase becomes dislocated from ER membranes into the cytosol of sterol-treated cells. This dislocation exhibits an absolute requirement for the actions of Insigs and VCP/p97. Reductase also appears in a buoyant fraction of sterol-treated cells that co-purifies with lipid droplets, cytosolic organelles traditionally regarded as storage depots for neutral lipids such as triglycerides and cholesteryl esters. Genetic, biochemical, and localization studies suggest a model in which reductase is dislodged into the cytosol from an ER subdomain closely associated with lipid droplets.
authors.affiliation: Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 74390-9046, USA.
authors.forename: Isamu Z
authors.initials: IZ
authors.lastname: Hartman
authors.forename: Pingsheng
authors.initials: P
authors.lastname: Liu
authors.forename: John K
authors.initials: JK
authors.lastname: Zehmer
authors.forename: Katherine
authors.initials: K
authors.lastname: Luby-Phelps
authors.forename: Youngah
authors.initials: Y
authors.lastname: Jo
authors.forename: Richard G W
authors.initials: RG
authors.lastname: Anderson
authors.forename: Russell A
authors.initials: RA
authors.lastname: DeBose-Boyd
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003600:Cytosol / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D013261:Sterols / Q000737:chemistry / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism*; D025801:Ubiquitin / Q000737:chemistry
chemical_list: D008055:Lipids; D013261:Sterols; D025801:Ubiquitin; D006903:Hydroxymethylglutaryl CoA Reductases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
references.citation: Nature. 2007 Jul 26;448(7152):435-8
references.pmid: 17653186
references.citation: Nat Cell Biol. 2005 Aug;7(8):766-72
references.pmid: 16056268
references.citation: J Cell Biol. 1992 Jun;117(5):959-73
references.pmid: 1374417
references.citation: J Lipid Res. 1995 Jun;36(6):1211-26
references.pmid: 7665999
references.citation: Nature. 2004 Jun 24;429(6994):834-40
references.pmid: 15215855
references.citation: J Biol Chem. 2003 May 2;278(18):15998-6007
references.pmid: 12591929
references.citation: J Biol Chem. 2003 Dec 26;278(52):52479-90
references.pmid: 14563840
references.citation: J Biol Chem. 2001 Feb 9;276(6):4365-72
references.pmid: 11085986
references.citation: J Biol Chem. 1985 Jan 10;260(1):522-30
references.pmid: 3965461
references.citation: J Cell Biol. 1980 Oct;87(1):180-96
references.pmid: 7191426
references.citation: Cell. 2002 Aug 23;110(4):489-500
references.pmid: 12202038
references.citation: J Biol Chem. 2008 Oct 17;283(42):28005-9
references.pmid: 18611863
references.citation: J Biol Chem. 2006 Dec 22;281(51):39308-15
references.pmid: 17043353
references.citation: Mol Cell. 2003 Jan;11(1):25-33
references.pmid: 12535518
references.citation: J Cell Sci. 2008 Jul 15;121(Pt 14):2415-22
references.pmid: 18577578
references.citation: J Biol Chem. 1988 Jun 25;263(18):8929-37
references.pmid: 3379053
references.citation: J Biol Chem. 1997 Aug 8;272(32):20213-21
references.pmid: 9242699
references.citation: Mol Cell. 2005 Sep 16;19(6):829-40
references.pmid: 16168377
references.citation: Immunity. 1997 Jul;7(1):113-22
references.pmid: 9252124
references.citation: Proc Natl Acad Sci U S A. 2006 Mar 28;103(13):4958-63
references.pmid: 16549805
references.citation: Mol Biol Cell. 2006 Jun;17(6):2674-83
references.pmid: 16597703
references.citation: J Antibiot (Tokyo). 1986 Sep;39(9):1211-8
references.pmid: 3781919
references.citation: Nature. 2008 May 29;453(7195):657-61
references.pmid: 18408709
references.citation: J Biol Chem. 2004 Jan 30;279(5):3787-92
references.pmid: 14597625
references.citation: J Proteome Res. 2007 Aug;6(8):3256-65
references.pmid: 17608402
references.citation: Methods Enzymol. 1983;98:241-60
references.pmid: 6321901
references.citation: Proc Natl Acad Sci U S A. 1983 Dec;80(23):7165-9
references.pmid: 6580634
references.citation: J Biol Chem. 1995 May 19;270(20):12152-61
references.pmid: 7744865
references.citation: Nature. 1996 Dec 5;384(6608):432-8
references.pmid: 8945469
references.citation: Proc Natl Acad Sci U S A. 2008 Aug 26;105(34):12325-30
references.pmid: 18711132
references.citation: J Biol Chem. 2009 May 29;284(22):14710-22
references.pmid: 19324879
references.citation: J Biol Chem. 1978 Feb 25;253(4):1121-8
references.pmid: 624722
references.citation: Cell. 2006 Jan 13;124(1):35-46
references.pmid: 16413480
references.citation: Nat Rev Mol Cell Biol. 2008 Dec;9(12):944-57
references.pmid: 19002207
references.citation: Nature. 2004 Jun 24;429(6994):841-7
references.pmid: 15215856
references.citation: J Biol Chem. 2002 May 17;277(20):17377-80
references.pmid: 12006608
references.citation: Histochem Cell Biol. 2008 Aug;130(2):263-79
references.pmid: 18546013
references.citation: J Cell Biol. 1983 Oct;97(4):1156-68
references.pmid: 6684660
references.citation: J Biol Chem. 1983 Jul 10;258(13):8450-5
references.pmid: 6688077
references.citation: J Lipid Res. 1980 Jul;21(5):505-17
references.pmid: 6995544
references.citation: J Cell Mol Med. 2008 Dec;12(6A):2511-8
references.pmid: 18798739
references.citation: J Biol Chem. 2005 Dec 30;280(52):42841-7
references.pmid: 16115879
references.citation: J Cell Biol. 2002 Apr 29;157(3):381-94
references.pmid: 11980915
references.citation: Mol Biol Cell. 2009 Jul;20(14):3330-41
references.pmid: 19458199
references.citation: EMBO J. 2003 Mar 3;22(5):1036-46
references.pmid: 12606569
references.citation: Cell. 1999 Dec 23;99(7):703-12
references.pmid: 10619424
references.citation: J Cell Sci. 2008 Jun 1;121(11):1852-60
references.pmid: 18477614
references.citation: FASEB J. 2007 Jan;21(1):167-78
references.pmid: 17135363
references.citation: J Lipid Res. 2006 Jan;47(1):87-98
references.pmid: 16230742
references.citation: J Biol Chem. 1984 Jun 25;259(12):7577-83
references.pmid: 6429133
references.citation: Cell. 1996 Mar 8;84(5):769-79
references.pmid: 8625414