Rho-kinase induces association of adducin with the cytoskeleton in platelet activation |
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Authors: | Tamaru Satoshi Fukuta Tetsu Kaibuchi Kozo Matsuoka Yoichiro Shiku Hiroshi Nishikawa Masakatsu |
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Institution: | The 2nd Department of Internal Medicine, Mie University School of Medicine, Mie 514-8507, Japan. |
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Abstract: | 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. |
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Keywords: | Platelet activation Cytoskeleton Membrane skeleton Rho-kinase Protein kinase C Adducin Actin Spectrin |
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