title: Mthfr deficiency induces endothelial progenitor cell senescence via uncoupling of eNOS and downregulation of SIRT1.
abstract: Hyperhomocysteinemia (HHcy) has been shown to induce endothelial dysfunction in part as a result of enhanced oxidative stress. Function and survival of endothelial progenitor cells (EPCs, defined as sca1(+) c-kit(+) flk-1(+) bone marrow-derived cells), which significantly contribute to neovascularization and endothelial regeneration, depend on controlled production of reactive oxygen species (ROS). Mice heterozygous for the gene deletion of methylenetetrahydrofolate reductase (Mthfr(+/-)) have a 1.5- to 2-fold elevation in plasma homocysteine. This mild HHcy significantly reduced the number of circulating EPCs as well as their differentiation. Mthfr deficiency was also associated with increased ROS production and reduced nitric oxide (NO) generation in Mthfr(+/-) EPCs. Treatment of EPCs with sepiapterin, a precursor of tetrahydrobiopterin (BH(4)), a cofactor of endothelial nitric oxide synthase (eNOS), significantly reduced ROS and improved NO production. mRNA and protein expression of eNOS and the relative amount of eNOS dimer compared with monomer were decreased by Mthfr deficiency. Impaired differentiation of EPCs induced by Mthfr deficiency correlated with increased senescence, decreased telomere length, and reduced expression of SIRT1. Addition of sepiapterin maintained cell senescence and SIRT1 expression at levels comparable to the wild type. Taken together, these results demonstrate that Mthfr deficiency impairs EPC formation and increases EPC senescence by eNOS uncoupling and downregulation of SIRT1.
authors.affiliation: Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Lemarié
authors.forename: Layla
authors.initials: L
authors.lastname: Shbat
authors.forename: Chiara
authors.initials: C
authors.lastname: Marchesi
authors.forename: Orlando J
authors.initials: OJ
authors.lastname: Angulo
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Deschênes
authors.forename: Mark D
authors.initials: MD
authors.lastname: Blostein
authors.forename: Pierre
authors.initials: P
authors.lastname: Paradis
authors.forename: Ernesto L
authors.initials: EL
authors.lastname: Schiffrin
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D016922:Cellular Senescence / Q000235:genetics*; D015536:Down-Regulation; D042783:Endothelial Cells / Q000201:enzymology*; D005260:Female; D006712:Homocystinuria / Q000235:genetics; D020138:Hyperhomocysteinemia / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000172:deficiency / Q000235:genetics; D051379:Mice; D009128:Muscle Spasticity / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D011618:Psychotic Disorders / Q000235:genetics; D011622:Pterins / Q000494:pharmacology; D017382:Reactive Oxygen Species; D056564:Sirtuin 1 / Q000378:metabolism*; D013234:Stem Cells / Q000201:enzymology*; D016615:Telomere / Q000378:metabolism
chemical_list: D011622:Pterins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; C016727:sepiapterin; D052250:Nitric Oxide Synthase Type III; D042965:Methylenetetrahydrofolate Reductase (NADPH2); C470545:Sirt1 protein, mouse; D056564:Sirtuin 1