title: SIRT1 Protects Against Oxidative Stress-Induced Endothelial Progenitor Cells Apoptosis by Inhibiting FOXO3a via FOXO3a Ubiquitination and Degradation.
abstract: Cell loss due to apoptosis induced by oxidative stress is a major hurdle for endothelial progenitor cells (EPCs)-based therapy. Sirtuin 1 (SIRT1) plays important roles in many pathophysiological processes by deacetylating various substrates, including forkhead transcription factor (FOXO). However, after deacetylation, the fate of FOXO protein remains to be explored. In the present study, we investigated whether SIRT1 exerted a protective effect on hydrogen peroxide (H(2)O(2))-induced EPCs apoptosis and, if so, what the underlying mechanism might be. EPCs were isolated and obtained from human umbilical cord blood by density gradient centrifugation and identified by morphology, tube formation ability, cell surface markers, and the ability to take up acetylated low-density lipoprotein (Dil-Ac-LDL) and bind ulex europaeus agglutinin 1 (FITC-UEA-1). Immunofluorescence showed that SIRT1 is localized in the nucleus of EPCs in the presence or absence of H(2)O(2). SIRT1 protein level in EPCs was increased by the treatment with H(2)O(2) for 24 h. Incubation of EPCs with H(2)O(2) dose dependently induced EPCs apoptosis. SIRT1 overexpression reduced the rate of EPCs apoptosis induced by H(2)O(2), whereas SIRT1 downregulation and EX527, a specific SIRT1 inhibitor, exerted the opposite effect. SIRT1 overexpression decreased the total FOXO3a protein expression, whereas SIRT1 downregulation and EX527 increased the amount of FOXO3a protein. SIRT1 reduced FOXO3a transcriptional activity according to Bim expression. Co-immunoprecipitation assay showed that SIRT1 could bind to FOXO3a, reduce its acetylation level and increase its ubiquitination level. To sum up, our work demonstrated that SIRT1 had a pivotally protective role in the regulation of EPCs apoptosis induced by H(2)O(2) and that SIRT1 protected against apoptosis by inhibiting FOXO3a via FOXO3a ubiquitination and subsequent degradation.
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Yu-Qiang
authors: YQ
authors: Wang
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Qing
authors: Q
authors: Cao
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Fei
authors: F
authors: Wang
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Li-Ya
authors: LY
authors: Huang
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Tian-Tian
authors: TT
authors: Sang
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Fang
authors: F
authors: Liu
authors: Department of Geriatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Shu-Yan
authors: SY
authors: Chen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D066026:Endothelial Progenitor Cells / Q000187:drug effects; D005312:Fetal Blood; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics*; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage; D018384:Oxidative Stress / Q000235:genetics*; D059748:Proteolysis / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D056564:Sirtuin 1 / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects; D054875:Ubiquitination / Q000235:genetics
chemical_list: C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D006861:Hydrogen Peroxide; C447939:SIRT1 protein, human; D056564:Sirtuin 1