title: SIRT3 Deacetylates Ceramide Synthases: IMPLICATIONS FOR MITOCHONDRIAL DYSFUNCTION AND BRAIN INJURY.
abstract: Experimental evidence supports the role of mitochondrial ceramide accumulation as a cause of mitochondrial dysfunction and brain injury after stroke. Herein, we report that SIRT3 regulates mitochondrial ceramide biosynthesis via deacetylation of ceramide synthase (CerS) 1, 2, and 6. Reciprocal immunoprecipitation experiments revealed that CerS1, CerS2, and CerS6, but not CerS4, are associated with SIRT3 in cerebral mitochondria. Furthermore, CerS1, -2, and -6 are hyperacetylated in the mitochondria of SIRT3-null mice, and SIRT3 directly deacetylates the ceramide synthases in a NAD(+)-dependent manner that increases enzyme activity. Investigation of the SIRT3 role in mitochondrial response to brain ischemia/reperfusion (IR) showed that SIRT3-mediated deacetylation of ceramide synthases increased enzyme activity and ceramide accumulation after IR. Functional studies demonstrated that absence of SIRT3 rescued the IR-induced blockade of the electron transport chain at the level of complex III, attenuated mitochondrial outer membrane permeabilization, and decreased reactive oxygen species generation and protein carbonyls in mitochondria. Importantly, Sirt3 gene ablation reduced the brain injury after IR. These data support the hypothesis that IR triggers SIRT3-dependent deacetylation of ceramide synthases and the elevation of ceramide, which could inhibit complex III, leading to increased reactive oxygen species generation and brain injury. The results of these studies highlight a novel mechanism of SIRT3 involvement in modulating mitochondrial ceramide biosynthesis and suggest an important role of SIRT3 in mitochondrial dysfunction and brain injury after experimental stroke.
authors.affiliation: the Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425.
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Novgorodov
authors.affiliation: From the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Riley
authors.affiliation: the Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425.
authors.forename: Jarryd A
authors.initials: JA
authors.lastname: Keffler
authors.affiliation: the Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425.
authors.forename: Jin
authors.initials: J
authors.lastname: Yu
authors.affiliation: From the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Kindy
authors.affiliation: the Department of Cell and Developmental Biology, University of Colorado, Aurora, Colorado 80045, and.
authors.forename: Wendy B
authors.initials: WB
authors.lastname: Macklin
authors.affiliation: the Department of Pathology and Institute of Gerontology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: David B
authors.initials: DB
authors.lastname: Lombard
authors.affiliation: the Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425,; From the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401,. Electronic address: gudz@musc.edu.
authors.forename: Tatyana I
authors.initials: TI
authors.lastname: Gudz
mesh_terms: D000818:Animals; D017209:Apoptosis; D001930:Brain Injuries / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D002518:Ceramides / Q000378:metabolism; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D056566:Sirtuin 3 / Q000235:genetics / Q000378:metabolism*; D051049:Sphingosine N-Acyltransferase / Q000235:genetics / Q000378:metabolism*
chemical_list: D002518:Ceramides; D008565:Membrane Proteins; C525046:Sirt3 protein, mouse; C584439:CERS6 protein, mouse; C000609885:CerS1 protein, mouse; C580723:Cers2 protein, mouse; D051049:Sphingosine N-Acyltransferase; D056566:Sirtuin 3
keywords: brain; ceramide synthase; mitochondria; sirtuin; sphingolipid