title: Downregulation of dynamin-related protein 1 contributes to impaired autophagic flux and angiogenic function in senescent endothelial cells.
abstract: OBJECTIVE
  Recent studies have shown that altered mitochondrial dynamics impairs the function in senescent endothelial cells (ECs). However, the underlying molecular mechanism remains to be elucidated. Herein, we investigated the role and underlying mechanism of mitochondrial fission protein dynamin-related protein 1 (DRP1) in vascular aging.
  
  
  RESULTS
  We found that DRP1 expression is decreased in senescent ECs, accompanied with long interconnected mitochondria and impaired angiogenic function. In addition, there was marked increase of autophagosomes but not of autolysosomes (assessed as punctate dual fluorescent mCherry-GFP (green fluorescent protein) tandem-tagged light chain 3 expression) in senescent ECs, indicating impaired autophagic flux. DRP1 knockdown or pharmacological inhibition in young ECs resulted in elongated mitochondria, suppressed autophagic flux, premature senescence, and impaired angiogenic function. In contrast, adenoviral-mediated overexpression of DRP1 in senescent ECs restored autophagic flux and improved angiogenic function. EC senescence was associated with the increase of mitochondrial reactive oxygen species and antioxidant N-acetyl-cysteine restored autophagosome clearance and improved angiogenic function. Consistently, en face staining of old rat thoracic aorta revealed a decrease of DRP1 expression and increase of autophagosomes accumulation. Furthermore, in vivo knockdown of Drp1 in common carotid arteries significantly impaired the autophagosome clearance. Importantly, downregulation of Drp1 directly abrogated microvessels outgrowth from ex vivo aortic rings.
  
  
  CONCLUSIONS
  These results suggest that loss of DRP1 during senescence exacerbates ECs dysfunction by increasing mitochondrial reactive oxygen species and subsequently inhibiting autophagic flux.
authors.affiliation: From the Laboratory of Vascular Biology and Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, China (J.-R.L., P.-J.G.); Shanghai Key Laboratory of Hypertension, Department of Hypertension, Ruijin Hospital and Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, Shanghai, China (W.-L.S., C.Y., P.-J.G.).
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Lin
authors.affiliation: From the Laboratory of Vascular Biology and Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, China (J.-R.L., P.-J.G.); Shanghai Key Laboratory of Hypertension, Department of Hypertension, Ruijin Hospital and Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, Shanghai, China (W.-L.S., C.Y., P.-J.G.).
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Shen
authors.affiliation: From the Laboratory of Vascular Biology and Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, China (J.-R.L., P.-J.G.); Shanghai Key Laboratory of Hypertension, Department of Hypertension, Ruijin Hospital and Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, Shanghai, China (W.-L.S., C.Y., P.-J.G.).
authors.forename: Chen
authors.initials: C
authors.lastname: Yan
authors.affiliation: From the Laboratory of Vascular Biology and Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, China (J.-R.L., P.-J.G.); Shanghai Key Laboratory of Hypertension, Department of Hypertension, Ruijin Hospital and Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, Shanghai, China (W.-L.S., C.Y., P.-J.G.). gaopingjin@sibs.ac.cn.
authors.forename: Ping-Jin
authors.initials: PJ
authors.lastname: Gao
mesh_terms: D000818:Animals; D001343:Autophagy; D016922:Cellular Senescence / Q000502:physiology*; D015536:Down-Regulation; D034281:Dynamins; D042783:Endothelial Cells / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D011921:Rats, Inbred WKY; D017382:Reactive Oxygen Species / Q000378:metabolism; D014472:Umbilicus / Q000098:blood supply; D014680:Veins
chemical_list: D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; D034281:Dynamins
keywords: aging; autophagy; endothelial dysfunction; mitochondria; reactive oxygen species