Rho associated coiled-coil kinase-1 regulates collagen-induced phosphatidylserine exposure in platelets

• Published in: PloS one 2013-12, Vol.8 (12), p.e84649-e84649
• Main Authors: Dasgupta, Swapan K, Le, Anhquyen, Haudek, Sandra B, Entman, Mark L, Rumbaut, Rolando E, Thiagarajan, Perumal
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Activation; Amides - pharmacology; Animals; Blood platelets; Blood Platelets - drug effects; Blood Platelets - metabolism; Blood Platelets - pathology; Calcium; Calcium signalling; Cofilin; Cofilin 1 - metabolism; Collagen; Collagen - pharmacology; Comparative analysis; Cytoskeleton; Defects; Enzyme inhibitors; Exposure; Humans; Inflammatory diseases; Laboratory animals; Light levels; LIM kinase; Lim Kinases - metabolism; Lipids; Medicine; Mice; Mice, Knockout; Muscle proteins; Myosin; Occlusion; Pathology; Phosphatases; Phosphatidylserine; Phosphatidylserines - pharmacology; Phospholipids; Phosphorylation; Physicians; Platelet Aggregation - drug effects; Platelet Aggregation - physiology; Platelets; Pyridines - pharmacology; rho-Associated Kinases - genetics; rho-Associated Kinases - metabolism; Senescence; Studies; Thrombin; Thrombin - biosynthesis; Thromboembolism; Thrombosis; Thrombosis - genetics; Veterans
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0084649

The transbilayer movement of phosphatidylserine mediates the platelet procoagulant activity during collagen stimulation. The Rho-associated coiled-coil kinase (ROCK) inhibitor Y-27632 inhibits senescence induced but not activation induced phosphatidylserine exposure. To investigate further the specific mechanisms, we now utilized mice with genetic deletion of the ROCK1 isoform. ROCK1-deficient mouse platelets expose significantly more phosphatidylserine and generate more thrombin upon activation with collagen compared to wild-type platelets. There were no significant defects in platelet shape change, aggregation, or calcium response compared to wild-type platelets. Collagen-stimulated ROCK1-deficient platelets also displayed decreased phosphorylation levels of Lim Kinase-1 and cofilin-1. However, there was no reduction in phosphorylation levels of myosin phosphatase subunit-1 (MYPT1) or myosin light chain (MLC). In an in vivo light/dye-induced endothelial injury/thrombosis model, ROCK1-deficient mice presented a shorter occlusion time in cremasteric venules when compared to wild-type littermates (3.16 ± 1.33 min versus 6.6 ± 2.6 min; p = 0.01). These studies define ROCK1 as a new regulator for collagen-induced phosphatidylserine exposure in platelets with functional consequences on thrombosis. This effect was downstream of calcium signaling and was mediated by Lim Kinase-1 / cofilin-1-induced cytoskeletal changes.