title: Disturbed Flow Induces Autophagy, but Impairs Autophagic Flux to Perturb Mitochondrial Homeostasis.
abstract: OBJECTIVE
  Temporal and spatial variations in shear stress are intimately linked with vascular metabolic effects. Autophagy is tightly regulated in intracellular bulk degradation/recycling system for maintaining cellular homeostasis. We postulated that disturbed flow modulates autophagy with an implication in mitochondrial superoxide (mtO2(•-)) production.
  
  
  RESULTS
  In the disturbed flow or oscillatory shear stress (OSS)-exposed aortic arch, we observed prominent staining of p62, a reverse marker of autophagic flux, whereas in the pulsatile shear stress (PSS)-exposed descending aorta, p62 was attenuated. OSS significantly increased (i) microtubule-associated protein light chain 3 (LC3) II to I ratios in human aortic endothelial cells, (ii) autophagosome formation as quantified by green fluorescent protein (GFP)-LC3 dots per cell, and (iii) p62 protein levels, whereas manganese superoxide dismutase (MnSOD) overexpression by recombinant adenovirus, N-acetyl cysteine treatment, or c-Jun N-terminal kinase (JNK) inhibition reduced OSS-mediated LC3-II/LC3-I ratios and mitochondrial DNA damage. Introducing bafilomycin to Earle's balanced salt solution or to OSS condition incrementally increased both LC3-II/LC3-I ratios and p62 levels, implicating impaired autophagic flux. In the OSS-exposed aortic arch, both anti-phospho-JNK and anti-8-hydroxy-2'-deoxyguanosine (8-OHdG) staining for DNA damage were prominent, whereas in the PSS-exposed descending aorta, the staining was nearly absent. Knockdown of ATG5 with siRNA increased OSS-mediated mtO2(•-), whereas starvation or rapamycin-induced autophagy reduced OSS-mediated mtO2(•-), mitochondrial respiration, and complex II activity.
  
  
  METHODS
  Disturbed flow-mediated oxidative stress and JNK activation induce autophagy.
  
  
  CONCLUSIONS
  OSS impairs autophagic flux to interfere with mitochondrial homeostasis. Antioxid. Redox Signal. 23, 1207-1219.
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Rongsong
authors.initials: R
authors.lastname: Li
authors.affiliation: 2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California.
authors.forename: Nelson
authors.initials: N
authors.lastname: Jen
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Lan
authors.initials: L
authors.lastname: Wu
authors.affiliation: 2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California.
authors.forename: Juhyun
authors.initials: J
authors.lastname: Lee
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Karen
authors.initials: K
authors.lastname: Fang
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Katherine
authors.initials: K
authors.lastname: Quigley
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Katherine
authors.initials: K
authors.lastname: Lee
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Sky
authors.initials: S
authors.lastname: Wang
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Bill
authors.initials: B
authors.lastname: Zhou
authors.affiliation: 3 Department of Human Genetics, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Laurent
authors.initials: L
authors.lastname: Vergnes
authors.affiliation: 4 Department of Molecular Pharmacology, Beckman Research Institute, City of Hope National Medical Center , Duarte, California.
authors.forename: Yun-Ru
authors.initials: YR
authors.lastname: Chen
authors.affiliation: 5 Department of Medicine, VA Greater Los Angeles Healthcare System, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Li
authors.affiliation: 3 Department of Human Genetics, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Karen
authors.initials: K
authors.lastname: Reue
authors.affiliation: 4 Department of Molecular Pharmacology, Beckman Research Institute, City of Hope National Medical Center , Duarte, California.
authors.forename: David K
authors.initials: DK
authors.lastname: Ann
authors.affiliation: 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.|2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California.|5 Department of Medicine, VA Greater Los Angeles Healthcare System, UCLA David Geffen School of Medicine , Los Angeles, California.
authors.forename: Tzung K
authors.initials: TK
authors.lastname: Hsiai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D001343:Autophagy; D001696:Biomechanical Phenomena; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000235:genetics; D006706:Homeostasis; D020935:MAP Kinase Signaling System; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D010101:Oxygen Consumption; D010588:Phagosomes / Q000378:metabolism; D011817:Rabbits; D012039:Regional Blood Flow
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004272:DNA, Mitochondrial