Sanjeev K Gotru1, Wenchun Chen1, Peter Kraft1, Isabelle C Becker1, Karen Wolf1, Simon Stritt1, Susanna Zierler1, Heike M Hermanns1, Deviyani Rao1, Anne-Laure Perraud1, Carsten Schmitz1, René P Zahedi1, Peter J Noy1, Michael G Tomlinson1, Thomas Dandekar1, Masayuki Matsushita1, Vladimir Chubanov1, Thomas Gudermann1, Guido Stoll1, Bernhard Nieswandt2, Attila Braun2. 1. From the Institute of Experimental Biomedicine, University Hospital of Würzburg (S.K.G., W.C., I.C.B., K.W., S.S., B.N., A.B.), Rudolf Virchow Center (S.K.G., W.C., I.C.B., K.W., S.S., B.N., A.B.), and Institute of Clinical Epidemiology and Biometry, Comprehensive Heart Failure Center (P.K.), University of Würzburg, Germany; Department of Hepatology (H.M.H.) and Department of Neurology (P.K., G.S.), University Hospital of Würzburg, Germany; Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Germany (S.Z., V.C., T.G.); Department of Immunology and Microbiology, University of Colorado, Denver (D.R., A.-L.P., C.S.); National Jewish Health, Denver, CO (D.R., A.-L.P., C.S.); Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan (M.M.); Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany (R.P.Z.); School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, United Kingdom (P.J.N., M.G.T.); and Department of Bioinformatics, Functional Genomics and Systems Biology Group, University of Würzburg Biocenter, Germany (T.D.). 2. From the Institute of Experimental Biomedicine, University Hospital of Würzburg (S.K.G., W.C., I.C.B., K.W., S.S., B.N., A.B.), Rudolf Virchow Center (S.K.G., W.C., I.C.B., K.W., S.S., B.N., A.B.), and Institute of Clinical Epidemiology and Biometry, Comprehensive Heart Failure Center (P.K.), University of Würzburg, Germany; Department of Hepatology (H.M.H.) and Department of Neurology (P.K., G.S.), University Hospital of Würzburg, Germany; Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Germany (S.Z., V.C., T.G.); Department of Immunology and Microbiology, University of Colorado, Denver (D.R., A.-L.P., C.S.); National Jewish Health, Denver, CO (D.R., A.-L.P., C.S.); Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan (M.M.); Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany (R.P.Z.); School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, United Kingdom (P.J.N., M.G.T.); and Department of Bioinformatics, Functional Genomics and Systems Biology Group, University of Würzburg Biocenter, Germany (T.D.). attila.braun@virchow.uni-wuerzburg.de bernhard.nieswandt@virchow.uni-wuerzburg.de.
Abstract
OBJECTIVE: TRPM7 (transient receptor potential cation channel, subfamily M, member 7) is a ubiquitously expressed bifunctional protein comprising a transient receptor potential channel segment linked to a cytosolic α-type serine/threonine protein kinase domain. TRPM7 forms a constitutively active Mg2+ and Ca2+ permeable channel, which regulates diverse cellular processes in both healthy and diseased conditions, but the physiological role of TRPM7 kinase remains largely unknown. APPROACH AND RESULTS: Here we show that point mutation in TRPM7 kinase domain deleting the kinase activity in mice (Trpm7R/R ) causes a marked signaling defect in platelets. Trpm7R/R platelets showed an impaired PIP2 (phosphatidylinositol-4,5-bisphosphate) metabolism and consequently reduced Ca2+ mobilization in response to stimulation of the major platelet receptors GPVI (glycoprotein VI), CLEC-2 (C-type lectin-like receptor), and PAR (protease-activated receptor). Altered phosphorylation of Syk (spleen tyrosine kinase) and phospholipase C γ2 and β3 accounted for these global platelet activation defects. In addition, direct activation of STIM1 (stromal interaction molecule 1) with thapsigargin revealed a defective store-operated Ca2+ entry mechanism in the mutant platelets. These defects translated into an impaired platelet aggregate formation under flow and protection of the mice from arterial thrombosis and ischemic stroke in vivo. CONCLUSIONS: Our results identify TRPM7 kinase as a key modulator of phospholipase C signaling and store-operated Ca2+ entry in platelets. The protection of Trpm7R/R mice from acute ischemic disease without developing intracranial hemorrhage indicates that TRPM7 kinase might be a promising antithrombotic target.
OBJECTIVE:TRPM7 (transient receptor potential cation channel, subfamily M, member 7) is a ubiquitously expressed bifunctional protein comprising a transient receptor potential channel segment linked to a cytosolic α-type serine/threonine protein kinase domain. TRPM7 forms a constitutively active Mg2+ and Ca2+ permeable channel, which regulates diverse cellular processes in both healthy and diseased conditions, but the physiological role of TRPM7 kinase remains largely unknown. APPROACH AND RESULTS: Here we show that point mutation in TRPM7 kinase domain deleting the kinase activity in mice (Trpm7R/R ) causes a marked signaling defect in platelets. Trpm7R/R platelets showed an impaired PIP2 (phosphatidylinositol-4,5-bisphosphate) metabolism and consequently reduced Ca2+ mobilization in response to stimulation of the major platelet receptors GPVI (glycoprotein VI), CLEC-2 (C-type lectin-like receptor), and PAR (protease-activated receptor). Altered phosphorylation of Syk (spleen tyrosine kinase) and phospholipase C γ2 and β3 accounted for these global platelet activation defects. In addition, direct activation of STIM1 (stromal interaction molecule 1) with thapsigargin revealed a defective store-operated Ca2+ entry mechanism in the mutant platelets. These defects translated into an impaired platelet aggregate formation under flow and protection of the mice from arterial thrombosis and ischemic stroke in vivo. CONCLUSIONS: Our results identify TRPM7 kinase as a key modulator of phospholipase C signaling and store-operated Ca2+ entry in platelets. The protection of Trpm7R/R mice from acute ischemic disease without developing intracranial hemorrhage indicates that TRPM7 kinase might be a promising antithrombotic target.
Authors: Hong S Lu; Ann Marie Schmidt; Robert A Hegele; Nigel Mackman; Daniel J Rader; Christian Weber; Alan Daugherty Journal: Arterioscler Thromb Vasc Biol Date: 2019-12-23 Impact factor: 8.311
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