Thromb Haemost 2013; 110(06): 1215-1222
DOI: 10.1160/TH13-04-0335
Platelets and Blood Cells
Schattauer GmbH

Biphasic myosin II light chain activation during clot retraction

Marion Egot
1   Inserm UMR_S U765, Paris, France
2   Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, France
,
Alexandre Kauskot
1   Inserm UMR_S U765, Paris, France
2   Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, France
,
Dominique Lasne
1   Inserm UMR_S U765, Paris, France
2   Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, France
3   AP-HP, Laboratoire d’hématologie, Hôpital Necker, Paris, France
,
Pascale Gaussem
1   Inserm UMR_S U765, Paris, France
2   Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, France
4   AP-HP, Service d’hématologie biologique, Hôpital Européen Georges Pompidou, Paris, France
,
Christilla Bachelot-Loza
1   Inserm UMR_S U765, Paris, France
2   Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, France
› Author Affiliations

Financial support: This study was supported by grants from INSERM and from Région Ile de France CORDDIM (Marion Egot), two public funding agencies.
Further Information

Publication History

Received: 23 April 2013

Accepted after major revision: 05 August 2013

Publication Date:
30 November 2017 (online)

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Summary

Clot retraction is an essential step during primary haemostasis, thereby promoting thrombus stability and wound healing. Integrin αIIbβ3 plays a critical role in clot retraction, by inducing acto-myosin interactions that allow platelet cytoskeleton reorganisation. However, the signalling pathways that lead to clot retraction are still misunderstood. In this study, we report the first data on the kinetics of myosin II light chain (MLC) phosphorylation during clot retraction. We found an early phosphorylation peak followed by a second peak. By using specific inhibitors of kinases and small G proteins, we showed that MLC kinase (MLCK), RhoA/ROCK, and Rac-1 were involved in clot retraction and in the early MLC phosphorylation peak. Only Rac-1 and actin polymerisation, controlled by outside-in signalling, were crucial to the second MLC phosphorylation peak.