TY - JOUR
T1 - P21 activated kinase signaling coordinates glycoprotein receptor VI-mediated platelet aggregation, lamellipodia formation, and aggregate stability under shear
AU - Aslan, Joseph E.
AU - Itakura, Asako
AU - Haley, Kristina M.
AU - Tormoen, Garth W.
AU - Loren, Cassandra P.
AU - Baker, Sandra M.
AU - Pang, Jiaqing
AU - Chernoff, Jonathan
AU - McCarty, Owen J.T.
PY - 2013/6
Y1 - 2013/6
N2 - Objective-Rho GTPase proteins play a central role in regulating the dynamics of the platelet actin cytoskeleton. Yet, little is known regarding how Rho GTPase activation coordinates platelet activation and function. In this study, we aimed to characterize the role of the Rho GTPase effector, p21 activated kinase (PAK), in platelet activation, lamellipodia formation, and aggregate formation under shear. Approach and Results-Stimulation of platelets with the glycoprotein receptor VI agonist, collagen-related peptide, rapidly activated PAK in a time course preceding phosphorylation of PAK substrates, LIM domain kinase LIMK1 and the MAPK/ERK kinase MEK, and the subsequent activation of MAPKs and Akt. Pharmacological inhibitors of PAK blocked signaling events downstream of PAK and prevented platelet secretion as well as platelet aggregation in response to collagen-related peptide. PAK inhibitors also prevented PAK activation and platelet spreading on collagen surfaces. PAK was also required for the formation of platelet aggregates and to maintain aggregate stability under physiological shear flow conditions. Conclusions-These results suggest that PAK serves as an orchestrator of platelet functional responses after activation downstream of the platelet collagen receptor, glycoprotein receptor VI.
AB - Objective-Rho GTPase proteins play a central role in regulating the dynamics of the platelet actin cytoskeleton. Yet, little is known regarding how Rho GTPase activation coordinates platelet activation and function. In this study, we aimed to characterize the role of the Rho GTPase effector, p21 activated kinase (PAK), in platelet activation, lamellipodia formation, and aggregate formation under shear. Approach and Results-Stimulation of platelets with the glycoprotein receptor VI agonist, collagen-related peptide, rapidly activated PAK in a time course preceding phosphorylation of PAK substrates, LIM domain kinase LIMK1 and the MAPK/ERK kinase MEK, and the subsequent activation of MAPKs and Akt. Pharmacological inhibitors of PAK blocked signaling events downstream of PAK and prevented platelet secretion as well as platelet aggregation in response to collagen-related peptide. PAK inhibitors also prevented PAK activation and platelet spreading on collagen surfaces. PAK was also required for the formation of platelet aggregates and to maintain aggregate stability under physiological shear flow conditions. Conclusions-These results suggest that PAK serves as an orchestrator of platelet functional responses after activation downstream of the platelet collagen receptor, glycoprotein receptor VI.
KW - Blood Platelets/drug effects
KW - Carrier Proteins/pharmacology
KW - Cell Shape
KW - Enzyme Activation
KW - Humans
KW - Lim Kinases/blood
KW - MAP Kinase Kinase Kinases/blood
KW - Peptides/pharmacology
KW - Phosphorylation
KW - Platelet Activation/drug effects
KW - Platelet Aggregation/drug effects
KW - Platelet Membrane Glycoproteins/agonists
KW - Protein Kinase Inhibitors/pharmacology
KW - Pseudopodia/drug effects
KW - Signal Transduction/drug effects
KW - Stress, Mechanical
KW - Time Factors
KW - p21-Activated Kinases/antagonists & inhibitors
UR - http://www.scopus.com/inward/record.url?scp=84879079136&partnerID=8YFLogxK
UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=purepublist2023&SrcAuth=WosAPI&KeyUT=WOS:000320671800019&DestLinkType=FullRecord&DestApp=WOS
U2 - 10.1161/ATVBAHA.112.301165
DO - 10.1161/ATVBAHA.112.301165
M3 - Article
C2 - 23640496
SN - 1079-5642
VL - 33
SP - 1544
EP - 1551
JO - Arteriosclerosis, Thrombosis, and Vascular Biology
JF - Arteriosclerosis, Thrombosis, and Vascular Biology
IS - 7
ER -