title: The Sirt1 activator SRT3025 provides atheroprotection in Apoe-/- mice by reducing hepatic Pcsk9 secretion and enhancing Ldlr expression.
abstract: OBJECTIVE
  The deacetylase sirtuin 1 (Sirt1) exerts beneficial effects on lipid metabolism, but its roles in plasma LDL-cholesterol regulation and atherosclerosis are controversial. Thus, we applied the pharmacological Sirt1 activator SRT3025 in a mouse model of atherosclerosis and in hepatocyte culture.
  
  
  RESULTS
  Apolipoprotein E-deficient (Apoe(-/-)) mice were fed a high-cholesterol diet (1.25% w/w) supplemented with SRT3025 (3.18 g kg(-1) diet) for 12 weeks. In vitro, the drug activated wild-type Sirt1 protein, but not the activation-resistant Sirt1 mutant; in vivo, it increased deacetylation of hepatic p65 and skeletal muscle Foxo1. SRT3025 treatment decreased plasma levels of LDL-cholesterol and total cholesterol and reduced atherosclerosis. Drug treatment did not change mRNA expression of hepatic LDL receptor (Ldlr) and proprotein convertase subtilisin/kexin type 9 (Pcsk9), but increased their protein expression indicating post-translational effects. Consistent with hepatocyte Ldlr and Pcsk9 accumulation, we found reduced plasma levels of Pcsk9 after pharmacological Sirt1 activation. In vitro administration of SRT3025 to cultured AML12 hepatocytes attenuated Pcsk9 secretion and its binding to Ldlr, thereby reducing Pcsk9-mediated Ldlr degradation and increasing Ldlr expression and LDL uptake. Co-administration of exogenous Pcsk9 with SRT3025 blunted these effects. Sirt1 activation with SRT3025 in Ldlr(-/-) mice reduced neither plasma Pcsk9, nor LDL-cholesterol levels, nor atherosclerosis.
  
  
  CONCLUSIONS
  We identify reduction in Pcsk9 secretion as a novel effect of Sirt1 activity and uncover Ldlr as a prerequisite for Sirt1-mediated atheroprotection in mice. Pharmacological activation of Sirt1 appears promising to be tested in patients for its effects on plasma Pcsk9, LDL-cholesterol, and atherosclerosis.
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland Zurich Center of Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
authors.forename: Melroy X
authors.initials: MX
authors.lastname: Miranda
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Lambertus J
authors.initials: LJ
authors.lastname: van Tits
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Lohmann
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Tasneem
authors.initials: T
authors.lastname: Arsiwala
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Winnik
authors.affiliation: Institut Pasteur de Lille, Université Lille 2, INSERM UMR1011, EGID, Lille, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Tailleux
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland Laboratory of Integrative & Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL) Switzerland, Lausanne, Switzerland.
authors.forename: Sokrates
authors.initials: S
authors.lastname: Stein
authors.affiliation: Paul F. Glenn Laboratories for the Biological Mechanisms of Aging, Genetics Department, Harvard Medical School, Boston, MA, USA.
authors.forename: Ana P
authors.initials: AP
authors.lastname: Gomes
authors.affiliation: Sirtris, a GSK Company, Cambridge, MA, USA.
authors.forename: Vipin
authors.initials: V
authors.lastname: Suri
authors.affiliation: Sirtris, a GSK Company, Cambridge, MA, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Ellis
authors.affiliation: Zurich Center of Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Lutz
authors.affiliation: Zurich Center of Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Zurich, Switzerland.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Hottiger
authors.affiliation: Paul F. Glenn Laboratories for the Biological Mechanisms of Aging, Genetics Department, Harvard Medical School, Boston, MA, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Sinclair
authors.affiliation: Laboratory of Integrative & Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL) Switzerland, Lausanne, Switzerland.
authors.forename: Johan
authors.initials: J
authors.lastname: Auwerx
authors.affiliation: Laboratory of Integrative & Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL) Switzerland, Lausanne, Switzerland.
authors.forename: Kristina
authors.initials: K
authors.lastname: Schoonjans
authors.affiliation: Institut Pasteur de Lille, Université Lille 2, INSERM UMR1011, EGID, Lille, France.
authors.forename: Bart
authors.initials: B
authors.lastname: Staels
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland Zurich Center of Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Lüscher
authors.affiliation: Cardiovascular Research, Institute of Physiology, University of Zurich and University Heart Center, Cardiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland Zurich Center of Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland christian.matter@uzh.ch.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Matter
mesh_terms: D000813:Anilides / Q000494:pharmacology; D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology; D001057:Apolipoproteins E / Q000172:deficiency; D001161:Arteriosclerosis / Q000517:prevention & control*; D002478:Cells, Cultured; D008078:Cholesterol, LDL / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008810:Mice, Inbred C57BL; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011973:Receptors, LDL / Q000187:drug effects / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*; D056564:Sirtuin 1 / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000813:Anilides; D000924:Anticholesteremic Agents; D001057:Apolipoproteins E; D008078:Cholesterol, LDL; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D011973:Receptors, LDL; C000601293:SRT3025; D013844:Thiazoles; C472126:Pcsk9 protein, mouse; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D056564:Sirtuin 1
keywords: Atherogenesis; LDL receptor; LDL-cholesterol; Pcsk9; Sirt1