Role of TRPM2 channel in mediating H2O2-induced Ca2+ entry and endothelial hyperpermeability.
Oxidative stress through the production of oxygen metabolites such as hydrogen peroxide (H2O2) increases vascular endothelial permeability. H2O2 stimulates ADP-ribose formation, which in turn opens transient receptor potential melastatin (TRPM)2 channels. Here, in endothelial cells, we demonstrate transcript and protein expression of TRPM2, a Ca2+-permeable, nonselective cation channel. We further show the importance of TRPM2 expression in signaling of increased endothelial permeability by oxidative stress. Exposure of endothelial cell monolayers to sublytic concentrations of H2O2 induced a cationic current measured by patch-clamp recording and Ca2+ entry detected by intracellular fura-2 fluorescence. H2O2 in a concentration-dependent manner also decreased trans-monolayer transendothelial electrical resistance for 3 hours (with maximal effect seen at 300 micromol/L H2O2), indicating opening of interendothelial junctions. The cationic current, Ca2+ entry, and transendothelial electrical resistance decrease elicited by H2O2 were inhibited by siRNA depleting TRPM2 or antibody blocking of TRPM2. H2O2 responses were attenuated by overexpression of the dominant-negative splice variant of TRPM2 or inhibition of ADP-ribose formation. Overexpression of the full-length TRPM2 enhanced H2O2-mediated Ca2+ entry, cationic current, and the transendothelial electrical resistance decrease. Thus, TRPM2 mediates H2O2-induced increase in endothelial permeability through the activation of Ca2+ entry via TRPM2. TRPM2 represents a novel therapeutic target directed against oxidant-induced endothelial barrier disruption.
Hecquet
Claudie M
CM
Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA.
Ahmmed
Gias U
GU
Vogel
Stephen M
SM
Malik
Asrar B
AB
D000246:Adenosine Diphosphate Ribose / Q000037:antagonists & inhibitors / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002199:Capillary Permeability / Q000187:drug effects* / Q000502:physiology; D002413:Cations, Divalent / Q000378:metabolism; D002478:Cells, Cultured; D017097:Electric Impedance; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D034741:RNA, Small Interfering / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*
D002413:Cations, Divalent; D016877:Oxidants; D034741:RNA, Small Interfering; D050053:TRPM Cation Channels; D000246:Adenosine Diphosphate Ribose; D006861:Hydrogen Peroxide; D002118:Calcium