Nature Medicine
9, 1418 - 1422 (2003)
Published online: 5 October 2003; | doi:10.1038/nm943
G13 is an essential mediator of platelet activation in hemostasis and thrombosisAlexandra Moers1, Bernhard Nieswandt2, Steffen Massberg3, Nina Wettschureck1, Sabine Grüner2, Ildiko Konrad3, Valerie Schulte2, Barsom Aktas2, Marie-Pierre Gratacap1, 5, Melvin I Simon4, Meinrad Gawaz3
& Stefan Offermanns11
Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany. 2
Vascular Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97078 Würzburg, Germany. 3
Deutsches Herzzentrum und 1. Medizinische Klinik, Technische Universität München, D-80636 München, Germany. 4
Division of Biology 147-75, California Institute of Technology, Pasadena, California 91125, USA. 5
Present address: INSERM, Unité 326, Hôpital Purpan, 31059 Toulouse Cedex, France.
Correspondence should be addressed to Stefan Offermanns Stefan.Offermanns@urz.uni-heidelberg.dePlatelet activation at sites of vascular injury is essential for primary hemostasis, but also underlies arterial thrombosis leading to myocardial infarction or stroke1,
2. Platelet activators such as adenosine diphosphate, thrombin or thromboxane A2 (TXA2) activate receptors that are coupled to heterotrimeric G proteins1,
3. Activation of platelets through these receptors involves signaling through Gq, Gi and Gz (refs. 4−6). However, the role and relative importance of G12 and G13, which are activated by various platelet stimuli7,
8,
9, are unclear. Here we show that lack of G 13, but not G12, severely reduced the potency of thrombin, TXA2 and collagen to induce platelet shape changes and aggregation in vitro. These defects were accompanied by reduced activation of RhoA and inability to form stable platelet thrombi under high shear stress ex vivo. G13 deficiency in platelets resulted in a severe defect in primary hemostasis and complete protection against arterial thrombosis in vivo. We conclude that G13-mediated signaling processes are required for normal hemostasis and thrombosis and may serve as a new target for antiplatelet drugs.
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