Rho-kinase induces association of adducin with the cytoskeleton in platelet activation.
We examined whether adducin function is regulated through Rho-kinase after agonist stimulation in platelets. A variety of stimuli such as thrombin, STA(2) (a stable analog of TXA(2)), Ca(2+) ionophore, phorbol diester, and shear stress induced phosphorylation of alpha-adducin at Thr445. Preincubation with the Rho-kinase inhibitor Y-27632 in platelets inhibited agonist-induced phosphorylation of alpha-adducin. STA(2) stimulation led to a redistribution of adducin from Triton-insoluble (high speed) fraction (membrane skeleton) to Triton-insoluble (low speed) fraction (cytoskeleton) and detergent-soluble fraction. Phosphoadducin at Thr445 was selectively isolated in the cytoskeletal fraction, whereas phosphoadducin at Ser726 was mainly present in the Triton-soluble fraction. Y-27632 inhibition of STA(2)-induced alpha-adducin phosphorylation at Thr445 inhibited incorporation of alpha-adducin and spectrin into the platelet cytoskeleton, although Y-27632 did not affect phosphorylation of alpha-adducin at Ser726. These results suggest that Rho-kinase regulates the association of alpha-adducin and spectrin with the actin cytoskeleton in platelet activation.
Tamaru
Satoshi
S
The 2nd Department of Internal Medicine, Mie University School of Medicine, Mie 514-8507, Japan.
Fukuta
Tetsu
T
Kaibuchi
Kozo
K
Matsuoka
Yoichiro
Y
Shiku
Hiroshi
H
Nishikawa
Masakatsu
M
D001792:Blood Platelets / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D010766:Phosphorylation; D015539:Platelet Activation / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D054460:rho-Associated Kinases; D000099291:Adducins
D002148:Calmodulin-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D000099291:Adducins