{"id":{"repo_id":"utswmed","oai_identifier":"oai:utswmed-ir.tdl.org:2152.5/3571"},"canonical_url":"https://search.dev.ndltd.org/etd/utswmed/oai:utswmed-ir.tdl.org:2152.5/3571","repository":{"repo_id":"utswmed","name":"University of Texas Southwestern Medical Center","base_url":"https://utswmed-ir.tdl.org/server/oai/request"},"display":{"title":"Sequential Actions of VCP/p97 and the Proteasome 19S Regulatory Particle in Sterol-Accelerated, ER-Associated Degradation of HMG CoA Reductase","abstract":"Accelerated endoplasmic reticulum (ER)-associated degradation (ERAD) of the cholesterol biosynthetic enzyme HMG CoA reductase results from its sterol-induced binding to ER membrane proteins called Insig-1 and Insig-2. This binding allows for subsequent ubiquitination of reductase by Insig-associated ubiquitin ligases. Once ubiquitinated, reductase becomes dislocated from ER membranes into the cytosol for degradation by 26S proteasomes through poorly defined reactions mediated by the AAA-ATPase VCP/p97 and augmented by the nonsterol isoprenoid geranylgeraniol. Here, we report that the oxysterol 25-hydroxycholesterol and geranylgeraniol combine to trigger extraction of reductase across ER membranes prior to its cytosolic release. This conclusion was drawn from studies utilizing a novel assay that measures membrane extraction of reductase by determining susceptibility of a lumenal epitope in the enzyme to in vitro protease digestion. Susceptibility of the lumenal epitope to protease digestion, and thus membrane extraction of reductase, was tightly regulated by 25-hydroxycholesterol and geranylgeraniol. The reaction was inhibited by RNA interference mediated knockdown of either Insigs or VCP/p97. In contrast, reductase continued to become membrane extracted, but not cytosolically dislocated, in cells deficient for AAA-ATPases of the proteasome 19S regulatory particle. These findings establish sequential roles for VCP/p97 and the 19S regulatory particle in the sterol-accelerated ERAD of reductase that may be applicable to the ERAD of other substrates.","abstract_html":"Accelerated endoplasmic reticulum (ER)-associated degradation (ERAD) of the cholesterol biosynthetic enzyme HMG CoA reductase results from its sterol-induced binding to ER membrane proteins called Insig-1 and Insig-2. This binding allows for subsequent ubiquitination of reductase by Insig-associated ubiquitin ligases. Once ubiquitinated, reductase becomes dislocated from ER membranes into the cytosol for degradation by 26S proteasomes through poorly defined reactions mediated by the AAA-ATPase VCP/p97 and augmented by the nonsterol isoprenoid geranylgeraniol. Here, we report that the oxysterol 25-hydroxycholesterol and geranylgeraniol combine to trigger extraction of reductase across ER membranes prior to its cytosolic release. This conclusion was drawn from studies utilizing a novel assay that measures membrane extraction of reductase by determining susceptibility of a lumenal epitope in the enzyme to in vitro protease digestion. Susceptibility of the lumenal epitope to protease digestion, and thus membrane extraction of reductase, was tightly regulated by 25-hydroxycholesterol and geranylgeraniol. The reaction was inhibited by RNA interference mediated knockdown of either Insigs or VCP/p97. In contrast, reductase continued to become membrane extracted, but not cytosolically dislocated, in cells deficient for AAA-ATPases of the proteasome 19S regulatory particle. These findings establish sequential roles for VCP/p97 and the 19S regulatory particle in the sterol-accelerated ERAD of reductase that may be applicable to the ERAD of other substrates.","abstract_has_math":false,"creators":["Morris, Lindsey LaChelle"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Goodman, Joel M.","DeBose-Boyd, Russell A.","Lehrman, Mark A.","De Martino, George"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-09-01T19:16:50Z","date_published":"2016-09-01T19:16:50Z","updated_at":"2026-07-24T05:52:29Z","subjects":["Adenosine Triphosphatases","Endoplasmic Reticulum","Hydroxymethylglutaryl CoA Reductases","Metalloendopeptidases","Proteolysis","Sterols"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["957676349"],"render_values":[{"text":"957676349","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/2152.5/3571","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Goodman, Joel M.","DeBose-Boyd, Russell A.","Lehrman, Mark A.","De Martino, George"]},{"key":"dc:creator","label":"Author","values":["Morris, Lindsey LaChelle"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-09-01T19:16:50Z","2014-08","2014-05-28","August 2014","2016-09-01T19:07:40Z"]},{"key":"dc:type","label":"Dc Type","values":["Thesis","text"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Adenosine Triphosphatases","Endoplasmic Reticulum","Hydroxymethylglutaryl CoA Reductases","Metalloendopeptidases","Proteolysis","Sterols"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2152.5/3571","957676349"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Accelerated endoplasmic reticulum (ER)-associated degradation (ERAD) of the cholesterol biosynthetic enzyme HMG CoA reductase results from its sterol-induced binding to ER membrane proteins called Insig-1 and Insig-2. This binding allows for subsequent ubiquitination of reductase by Insig-associated ubiquitin ligases. Once ubiquitinated, reductase becomes dislocated from ER membranes into the cytosol for degradation by 26S proteasomes through poorly defined reactions mediated by the AAA-ATPase VCP/p97 and augmented by the nonsterol isoprenoid geranylgeraniol. Here, we report that the oxysterol 25-hydroxycholesterol and geranylgeraniol combine to trigger extraction of reductase across ER membranes prior to its cytosolic release. This conclusion was drawn from studies utilizing a novel assay that measures membrane extraction of reductase by determining susceptibility of a lumenal epitope in the enzyme to in vitro protease digestion. Susceptibility of the lumenal epitope to protease digestion, and thus membrane extraction of reductase, was tightly regulated by 25-hydroxycholesterol and geranylgeraniol. The reaction was inhibited by RNA interference mediated knockdown of either Insigs or VCP/p97. In contrast, reductase continued to become membrane extracted, but not cytosolically dislocated, in cells deficient for AAA-ATPases of the proteasome 19S regulatory particle. These findings establish sequential roles for VCP/p97 and the 19S regulatory particle in the sterol-accelerated ERAD of reductase that may be applicable to the ERAD of other substrates."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Sequential Actions of VCP/p97 and the Proteasome 19S Regulatory Particle in Sterol-Accelerated, ER-Associated Degradation of HMG CoA Reductase"]}]}],"canonical_facts":{"dc:contributor":["Goodman, Joel M.","DeBose-Boyd, Russell A.","Lehrman, Mark A.","De Martino, George"],"dc:creator":["Morris, Lindsey LaChelle"],"dc:date":["2016-09-01T19:16:50Z","2014-08","2014-05-28","August 2014","2016-09-01T19:07:40Z"],"dc:description":["Accelerated endoplasmic reticulum (ER)-associated degradation (ERAD) of the cholesterol biosynthetic enzyme HMG CoA reductase results from its sterol-induced binding to ER membrane proteins called Insig-1 and Insig-2. This binding allows for subsequent ubiquitination of reductase by Insig-associated ubiquitin ligases. Once ubiquitinated, reductase becomes dislocated from ER membranes into the cytosol for degradation by 26S proteasomes through poorly defined reactions mediated by the AAA-ATPase VCP/p97 and augmented by the nonsterol isoprenoid geranylgeraniol. Here, we report that the oxysterol 25-hydroxycholesterol and geranylgeraniol combine to trigger extraction of reductase across ER membranes prior to its cytosolic release. This conclusion was drawn from studies utilizing a novel assay that measures membrane extraction of reductase by determining susceptibility of a lumenal epitope in the enzyme to in vitro protease digestion. Susceptibility of the lumenal epitope to protease digestion, and thus membrane extraction of reductase, was tightly regulated by 25-hydroxycholesterol and geranylgeraniol. The reaction was inhibited by RNA interference mediated knockdown of either Insigs or VCP/p97. In contrast, reductase continued to become membrane extracted, but not cytosolically dislocated, in cells deficient for AAA-ATPases of the proteasome 19S regulatory particle. These findings establish sequential roles for VCP/p97 and the 19S regulatory particle in the sterol-accelerated ERAD of reductase that may be applicable to the ERAD of other substrates."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2152.5/3571","957676349"],"dc:language":["en"],"dc:subject":["Adenosine Triphosphatases","Endoplasmic Reticulum","Hydroxymethylglutaryl CoA Reductases","Metalloendopeptidases","Proteolysis","Sterols"],"dc:title":["Sequential Actions of VCP/p97 and the Proteasome 19S Regulatory Particle in Sterol-Accelerated, ER-Associated Degradation of HMG CoA Reductase"],"dc:type":["Thesis","text"]},"updated_at":"2026-07-24T05:52:29Z"}