TY - JOUR
T1 - Plasma membrane Ca2+-ATPase (PMCA) translocates to filopodia during platelet activation
AU - Dean, William L.
AU - Whiteheart, Sidney W.
PY - 2004/2
Y1 - 2004/2
N2 - The plasma membrane Ca2+-ATPase (PMCA) plays an essential role in maintaining low cytosolic Ca2+ in platelets. Recently we demonstrated that PMCA is recruited to the cytoskeleton by interacting with PDZ domains. In the present study we determined the subcellular localization of PMCA using immunofluorescence microscopy. In resting platelets PMCA was distributed over the entire plasma membrane. Upon activation with thrombin, PMCA was found in filopodia adjacent to the actin cytoskeleton. PMCA translocation to filopodia was prevented by a peptide containing the last 10 residues of PMCA4b, the predominate isoform of PMCA in platelets, which contains a known PDZ domain-binding motif and was previously shown to block association of PMCA with the cytoskeleton. Incorporation of the PMCA C-terminal peptide did not affect the rate or extent of platelet aggregation, but significantly enhanced the rate of clot retraction. These results show that PMCA association with the cytoskeleton during platelet activation results in translocation of this Ca2+-pump to filopodia and that this association may affect later stages of platelet activation. The consequence of PMCA translocation to filopodia is likely a reduction in the local concentration of free Ca2+ in these structures resulting in regulation of the rate of clot retraction.
AB - The plasma membrane Ca2+-ATPase (PMCA) plays an essential role in maintaining low cytosolic Ca2+ in platelets. Recently we demonstrated that PMCA is recruited to the cytoskeleton by interacting with PDZ domains. In the present study we determined the subcellular localization of PMCA using immunofluorescence microscopy. In resting platelets PMCA was distributed over the entire plasma membrane. Upon activation with thrombin, PMCA was found in filopodia adjacent to the actin cytoskeleton. PMCA translocation to filopodia was prevented by a peptide containing the last 10 residues of PMCA4b, the predominate isoform of PMCA in platelets, which contains a known PDZ domain-binding motif and was previously shown to block association of PMCA with the cytoskeleton. Incorporation of the PMCA C-terminal peptide did not affect the rate or extent of platelet aggregation, but significantly enhanced the rate of clot retraction. These results show that PMCA association with the cytoskeleton during platelet activation results in translocation of this Ca2+-pump to filopodia and that this association may affect later stages of platelet activation. The consequence of PMCA translocation to filopodia is likely a reduction in the local concentration of free Ca2+ in these structures resulting in regulation of the rate of clot retraction.
KW - Calcium signaling
KW - Filopodia
KW - Plasma membrane Ca-ATPase
KW - Platelets
UR - http://www.scopus.com/inward/record.url?scp=1242352036&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=1242352036&partnerID=8YFLogxK
U2 - 10.1160/th03-07-0425
DO - 10.1160/th03-07-0425
M3 - Article
C2 - 14961161
AN - SCOPUS:1242352036
SN - 0340-6245
VL - 91
SP - 325
EP - 333
JO - Thrombosis and Haemostasis
JF - Thrombosis and Haemostasis
IS - 2
ER -