biostudies-literatureAwasthi VNHLBI NIH HHS1447-55https://www.ebi.ac.uk/biostudies/studies/S-EPMC2647778biostudies-literatureUnknown27(6)<h4>Objective</h4>Coagulation factor VIIa (VIIa) binding to its cellular receptor, tissue factor (TF), not only initiates the coagulation cascade but also induces cell signaling by activating G-protein coupled protease-activated receptors. The objective of the present study is to investigate the role of lipid rafts and caveolae in modulating TF-VIIa signaling and coagulant functions.<h4>Methods and results</h4>TF-VIIa coagulant function was measured in factor X activation assay and the signaling function was evaluated in phosphoinositide hydrolysis and IL-8 gene induction. Buoyant density gradient centrifugation and immunofluorescence confocal microscopy were used to determine cellular localization of TF and protease-activated receptor 2. The data show that a substantial fraction of TF and protease-activated receptor 2 resides in lipid rafts/caveolae, and disruption of lipid rafts by cholesterol depletion or modification reduced TF-VIIa-induced cell signaling. Disruption of caveolae with caveolin-1 silencing had no effect on the TF-VIIa coagulant activity but inhibited the TF-VIIa-induced cell signaling.<h4>Conclusion</h4>Overall our data show that lipid raft/caveolae play a selective role in modulating the TF-VIIa signaling function without affecting the TF-VIIa coagulant activity.Arteriosclerosis, thrombosis, and vascular biologyModulation of tissue factor-factor VIIa signaling by lipid rafts and caveolae.PMC2647778HL 65500HL 58869R01 HL058869-08R01 HL058869R01 HL065500R01 HL065500-06Mandal SKPapanna VPendurthi URAwasthi VRao LVfalseModulation of tissue factor-factor VIIa signaling by lipid rafts and caveolae.<h4>Objective</h4>Coagulation factor VIIa (VIIa) binding to its cellular receptor, tissue factor (TF), not only initiates the coagulation cascade but also induces cell signaling by activating G-protein coupled protease-activated receptors. The objective of the present study is to investigate the role of lipid rafts and caveolae in modulating TF-VIIa signaling and coagulant functions.<h4>Methods and results</h4>TF-VIIa coagulant function was measured in factor X activation assay and the signaling function was evaluated in phosphoinositide hydrolysis and IL-8 gene induction. Buoyant density gradient centrifugation and immunofluorescence confocal microscopy were used to determine cellular localization of TF and protease-activated receptor 2. The data show that a substantial fraction of TF and protease-activated receptor 2 resides in lipid rafts/caveolae, and disruption of lipid rafts by cholesterol depletion or modification reduced TF-VIIa-induced cell signaling. Disruption of caveolae with caveolin-1 silencing had no effect on the TF-VIIa coagulant activity but inhibited the TF-VIIa-induced cell signaling.<h4>Conclusion</h4>Overall our data show that lipid raft/caveolae play a selective role in modulating the TF-VIIa signaling function without affecting the TF-VIIa coagulant activity.2007-01-01T00:00:00Z2007 Jun2024-11-21T09:43:17.441Z2019-03-27T00:20:54ZS-EPMC26477781741303910.1161/ATVBAHA.107.14343810.1161/atvbaha.107.143438