PECAM-1 and caveolae form the mechanosensing complex necessary for NOX2 activation and angiogenic signaling with stopped flow in pulmonary endothelium.
We showed that stop of flow triggers a mechanosignaling cascade that leads to the generation of reactive oxygen species (ROS); however, a mechanosensor coupled to the cytoskeleton that could potentially transduce flow stimulus has not been identified. We showed a role for KATP channel, caveolae (caveolin-1), and NADPH oxidase 2 (NOX2) in ROS production with stop of flow. Based on reports of a mechanosensory complex that includes platelet endothelial cell adhesion molecule-1 (PECAM-1) and initiates signaling with mechanical force, we hypothesized that PECAM-1 could serve as a mechanosensor in sensing disruption of flow. Using lungs in situ, we observed that ROS production with stop of flow was significantly reduced in PECAM-1(-/-) lungs compared with lungs from wild-type (WT) mice. Lack of PECAM-1 did not affect NOX2 activation machinery or the caveolin-1 expression or caveolae number in the pulmonary endothelium. Stop of flow in vitro triggered an increase in angiogenic potential of WT pulmonary microvascular endothelial cells (PMVEC) but not of PECAM-1(-/-) PMVEC. Obstruction of flow in lungs in vivo showed that the neutrophil infiltration as observed in WT mice was significantly lowered in PECAM-1(-/-) mice. With stop of flow, WT lungs showed higher expression of the angiogenic marker VEGF compared with untreated (sham) and PECAM-1(-/-) lungs. Thus PECAM-1 (and caveolae) are parts of the mechanosensing machinery that generates superoxide with loss of shear; the resultant ROS potentially drives neutrophil influx and acts as an angiogenic signal.
Institute for Environmental Medicine, Univ. of Pennsylvania School of Medicine, 1 John Morgan Bldg., 3620 Hamilton Walk, Philadelphia, PA 19104-6068. shampac@mail.med.upenn.edu.
John
J
Noel
Hui
H
Wang
Nankang
N
Hong
Jian-Qin
JQ
Tao
Kevin
K
Yu
Elena M
EM
Sorokina
Kristine
K
Debolt
Michelle
M
Heayn
Victor
V
Rizzo
Horace
H
Delisser
Aron B
AB
Fisher
Shampa
S
Chatterjee
D042702:Angiopoietin-2 / Q000502:physiology; D000818:Animals; D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D004789:Enzyme Activation; D015870:Gene Expression; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply* / Q000201:enzymology; D008297:Male; D040542:Mechanotransduction, Cellular; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055806:Microvessels / Q000166:cytology / Q000502:physiology*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D018919:Neovascularization, Physiologic; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D017382:Reactive Oxygen Species / Q000378:metabolism; D012039:Regional Blood Flow; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D042702:Angiopoietin-2; D051242:Caveolin 1; D008562:Membrane Glycoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D017382:Reactive Oxygen Species; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases
Katp (Kir6.2) channel; NOX2; PECAM; angiogenic potential; mechanotransduction; pulmonary endothelium; stop of flow