title: Inhibition of Rab prenylation by statins induces cellular glycosphingolipid remodeling.
abstract: Statins, which specifically inhibit HMG Co-A reductase, the rate-limiting step of cholesterol biosynthesis, are widely prescribed to reduce serum cholesterol and cardiac risk, but many other effects are seen. We now show an effect of these drugs to induce profound changes in the step-wise synthesis of glycosphingolipids (GSLs) in the Golgi. Glucosylceramide (GlcCer) was increased several-fold in all cell lines tested, demonstrating a widespread effect. Additionally, de novo or elevated lactotriaosylceramide (Lc3Cer; GlcNAcβ1-3Galβ1-4GlcCer) synthesis was observed in 70%. Western blot showed that GlcCer synthase (GCS) was elevated by statins, and GCS and Lc3Cer synthase (Lc3S) activities were increased; however, transcript was elevated for Lc3S only. Supplementation with the isoprenoid precursor, geranylgeranyl pyrophosphate (GGPP), a downstream product of HMG Co-A reductase, reversed statin-induced glycosyltransferase and GSL elevation. The Rab geranylgeranyl transferase inhibitor 3-PEHPC, but not specific inhibitors of farnesyl transferase, or geranylgeranyl transferase I, was sufficient to replicate statin-induced GlcCer and Lc3Cer synthesis, supporting a Rab prenylation-dependent mechanism. While total cholesterol was unaffected, the trans-Golgi network (TGN) cholesterol pool was dissipated and medial Golgi GCS partially relocated by statins. GSL-dependent vesicular retrograde transport of Verotoxin and cholera toxin to the Golgi/endoplasmic reticulum were blocked after statin or 3-PEHPC treatment, suggesting aberrant, prenylation-dependent vesicular traffic as a basis of glycosyltransferase increase and GSL remodeling. These in vitro studies indicate a previously unreported link between Rab prenylation and regulation of GCS activity and GlcCer metabolism.
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada.
authors.forename: Beth
authors.initials: B
authors.lastname: Binnington
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada.
authors.forename: Long
authors.initials: L
authors.lastname: Nguyen
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada Department of Biochemistry.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Kamani
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada.
authors.forename: Delowar
authors.initials: D
authors.lastname: Hossain
authors.affiliation: Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, MN, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Marks
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
authors.forename: Monique
authors.initials: M
authors.lastname: Budani
authors.affiliation: Research Institute, Program in Molecular Structure and Function, The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 1X8, Canada Department of Biochemistry Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada cling@sickkids.on.ca.
authors.forename: Clifford A
authors.initials: CA
authors.lastname: Lingwood
mesh_terms: D000924:Anticholesteremic Agents / Q000494:pharmacology*; D002518:Ceramides / Q000378:metabolism*; D051228:Geranyltranstransferase / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D061986:MCF-7 Cells; D017368:Protein Prenylation / Q000187:drug effects*; D021381:Protein Transport; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000924:Anticholesteremic Agents; D002518:Ceramides; D051228:Geranyltranstransferase; D020691:rab GTP-Binding Proteins
keywords: Golgi; UGCG; Verotoxin-cholera toxin retrograde transport; glucosylceramide; lactotriaosylceramide