title: Impairment of autophagy in endothelial cells prevents shear-stress-induced increases in nitric oxide bioavailability.
abstract: Autophagy is a lysosomal catabolic process by which cells degrade or recycle their contents to maintain cellular homeostasis, adapt to stress, and respond to disease. Impairment of autophagy in endothelial cells studied under static conditions results in oxidant stress and impaired nitric oxide (NO) bioavailability. We tested the hypothesis that vascular autophagy is also important for induction of NO production caused by exposure of endothelial cells to shear stress (i.e., 3 h × ≈20 dyn/cm(2)). Atg3 is a requisite autophagy pathway mediator. Control cells treated with non-targeting control siRNA showed increased autophagy, reactive oxygen species (ROS) production, endothelial NO synthase (eNOS) phosphorylation, and NO production upon exposure to shear stress (p < 0.05 for all). In contrast, cells with >85% knockdown of Atg3 protein expression (via Atg3 siRNA) exhibited a profound impairment of eNOS phosphorylation, and were incapable of increasing NO in response to shear stress. Moreover, ROS accumulation and inflammatory cytokine production (MCP-1 and IL-8) were exaggerated (all p < 0.05) in response to shear stress. These findings reveal that autophagy not only plays a critical role in maintaining NO bioavailability, but may also be a key regulator of oxidant-antioxidant balance and inflammatory-anti-inflammatory balance that ultimately regulate endothelial cell responses to shear stress.
authors.affiliation: a College of Health, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Leena P
authors.initials: LP
authors.lastname: Bharath
authors.forename: Robert
authors.initials: R
authors.lastname: Mueller
authors.forename: Youyou
authors.initials: Y
authors.lastname: Li
authors.forename: Ting
authors.initials: T
authors.lastname: Ruan
authors.forename: David
authors.initials: D
authors.lastname: Kunz
authors.forename: Rebekah
authors.initials: R
authors.lastname: Goodrich
authors.forename: Tyler
authors.initials: T
authors.lastname: Mills
authors.forename: Lance
authors.initials: L
authors.lastname: Deeter
authors.forename: Ashot
authors.initials: A
authors.lastname: Sargsyan
authors.forename: Pon Velayutham
authors.initials: PV
authors.lastname: Anandh Babu
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Graham
authors.forename: J David
authors.initials: JD
authors.lastname: Symons
mesh_terms: D000818:Animals; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D031204:Caloric Restriction; D002417:Cattle; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005260:Female; D008297:Male; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D013314:Stress, Mechanical; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism
chemical_list: D000071183:Autophagy-Related Proteins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D044763:Ubiquitin-Conjugating Enzymes; C455621:ATG3 protein, human
keywords: blood flow; exercice; exercise; flux sanguin; mitochondrial turnover; mitophagie; mitophagy; nutrient deprivation; oxidant stress; privation nutritionnelle; stress oxydant; vasculaire; vascular; « turnover » mitochondrial