title: TLR4 activation of TRPC6-dependent calcium signaling mediates endotoxin-induced lung vascular permeability and inflammation.
abstract: Lung vascular endothelial barrier disruption and the accompanying inflammation are primary pathogenic features of acute lung injury (ALI); however, the basis for the development of both remains unclear. Studies have shown that activation of transient receptor potential canonical (TRPC) channels induces Ca(2+) entry, which is essential for increased endothelial permeability. Here, we addressed the role of Toll-like receptor 4 (TLR4) intersection with TRPC6-dependent Ca(2+) signaling in endothelial cells (ECs) in mediating lung vascular leakage and inflammation. We find that the endotoxin (lipopolysaccharide; LPS) induces Ca(2+) entry in ECs in a TLR4-dependent manner. Moreover, deletion of TRPC6 renders mice resistant to endotoxin-induced barrier dysfunction and inflammation, and protects against sepsis-induced lethality. TRPC6 induces Ca(2+) entry in ECs, which is secondary to the generation of diacylglycerol (DAG) induced by LPS. Ca(2+) entry mediated by TRPC6, in turn, activates the nonmuscle myosin light chain kinase (MYLK), which not only increases lung vascular permeability but also serves as a scaffold to promote the interaction of myeloid differentiation factor 88 and IL-1R-associated kinase 4, which are required for NF-κB activation and lung inflammation. Our findings suggest that TRPC6-dependent Ca(2+) entry into ECs, secondary to TLR4-induced DAG generation, participates in mediating both lung vascular barrier disruption and inflammation induced by endotoxin.
authors.affiliation: Department of Pharmacology, 2 Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 61605, USA.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Tauseef
authors.forename: Nebojsa
authors.initials: N
authors.lastname: Knezevic
authors.forename: Koteswara R
authors.initials: KR
authors.lastname: Chava
authors.forename: Monica
authors.initials: M
authors.lastname: Smith
authors.forename: Sukriti
authors.initials: S
authors.lastname: Sukriti
authors.forename: Nicholas
authors.initials: N
authors.lastname: Gianaris
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Obukhov
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Vogel
authors.forename: Dean E
authors.initials: DE
authors.lastname: Schraufnagel
authors.forename: Alexander
authors.initials: A
authors.lastname: Dietrich
authors.forename: Lutz
authors.initials: L
authors.lastname: Birnbaumer
authors.forename: Asrar B
authors.initials: AB
authors.lastname: Malik
authors.forename: Dolly
authors.initials: D
authors.lastname: Mehta
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002199:Capillary Permeability / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism; D053592:Interleukin-1 Receptor-Associated Kinases / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*; D000074287:TRPC6 Cation Channel; D051197:Toll-Like Receptor 4 / Q000378:metabolism*
chemical_list: D016207:Cytokines; D004075:Diglycerides; D008070:Lipopolysaccharides; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C492146:Trpc6 protein, mouse; D053592:Interleukin-1 Receptor-Associated Kinases; C507774:Irak4 protein, mouse; D009219:Myosin-Light-Chain Kinase; D002118:Calcium