title: Lung endothelial cell proliferation with decreased shear stress is mediated by reactive oxygen species.
abstract: Acute cessation of flow (ischemia) leads to depolarization of the endothelial cell (EC) membrane mediated by K(ATP) channels and followed by production of reactive oxygen species (ROS) from NADPH oxidase. We postulated that ROS are a signal for initiating EC proliferation associated with the loss of shear stress. Flow cytometry was used to identify proliferating CD31-positive pulmonary microvascular endothelial cells (mPMVECs) from wild-type, Kir6.2-/-, and gp91phox-/- mice. mPMVECs were labeled with PKH26 and cultured in artificial capillaries for 72 h at 5 dyn/cm2 (flow adaptation), followed by 24 h of stop flow or continued flow. ROS production during the first hour of ischemia was markedly diminished compared with wild-type mice in both types of gene-targeted mPMVECs. Cell proliferation was defined as the proliferation index (PI). After 72 h of flow, >98% of PKH26-labeled wild-type mPMVECs were at a single peak (PI 1.0) and the proportion of cells in the S+G2/M phases were at 5.8% on the basis of cell cycle analysis. With ischemia (24 h), PI increased to 2.5 and the ratio of cells in S+G2/M phases were at 35%. Catalase, diphenyleneiodonium, and cromakalim markedly inhibited ROS production and cell proliferation in flow-adapted wild-type mPMVECs. Significant effects of ischemia were not observed in Kir6.2-/- and gp91phox-/- cells. ANG II activation of NADPH oxidase was unaffected by KATP gene deletion. Thus loss of shear stress in flow-adapted mPMVECs results in cell division associated with ROS generated by NADPH oxidase. This effect requires a functioning cell membrane KATP channel.
authors.affiliation: Institute for Environmental Medicine, Univ. of Pennsylvania Medical Center, One John Morgan Bldg., Philadelphia, PA 19104-6068, USA.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Milovanova
authors.forename: Shampa
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Yefim
authors.initials: Y
authors.lastname: Manevich
authors.forename: Irina
authors.initials: I
authors.lastname: Kotelnikova
authors.forename: Kris
authors.initials: K
authors.lastname: Debolt
authors.forename: Muniswamy
authors.initials: M
authors.lastname: Madesh
authors.forename: Jonni S
authors.initials: JS
authors.lastname: Moore
authors.forename: Aron B
authors.initials: AB
authors.lastname: Fisher
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007511:Ischemia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008168:Lung / Q000098:blood supply*; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010641:Phenotype; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D011652:Pulmonary Circulation / Q000502:physiology*; D011673:Pulsatile Flow / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D000099161:Kcnj11 Channel
chemical_list: D000804:Angiotensin II; D005905:Glyburide; D007004:Hypoglycemic Agents; D008562:Membrane Glycoproteins; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D024661:Potassium Channels, Inwardly Rectifying; D017382:Reactive Oxygen Species; D014662:Vasoconstrictor Agents; D000099161:Kcnj11 Channel; C488842:Cybb protein, mouse