Role of caveolin located in the caveolae, identified as flask-shaped invaginations on the surface of the plasma membrane, involved in the mechanotrasduction of vascular system.

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Caveolae, identified as flask-shaped invaginations on the surface of the plasma membrane, have been considered to be hot spots for cell signaling, A variety of functional proteins, including ion channels, are localized in caveolae, and assembled with each other, resulting in expression of biological and pharmacological functions. We summarize herewith our results as following :1) Mechanotransduction and tyrosine kinase / tyrosine phosphorylation in cerebral and pulmonary arteries :The mechanisms of pressure-induced myogenic contraction was studied with regard to tyrosine phosphrylation were studied. Intracellular Ca concentration and vessel diameter were simultaneously measured. Furthermore, we tried to detect immunocytochemically in situ total tyrosine phosphorylation level and activity of pp60src in the arteries.2) Intracellular localization of protein kinase C isoforms in the contractile potentiation of coronary artery by agonistic stimuli and experimental cerebral vasospasm :Endoth … More elin 1 at a low concentration of 10-100pM potentiated 5-hydroxytryptamine-induced contraction of porcine coronary artery, which was consistent with translocation of protein kinase (PKC) a and d isoforms. Canine model of experimental cerebral vasospasm induced by injection of autologous blood injected into cisterna magna was also investigated with regard to PKC isoforms. PKC d was translocated to the membrane fraction during the development of the vasospasm, and PKC a was tanslocated in the late phase of established vasospasm. PKC a and d isoforms were densely located in caveolin-rich fraction. Furthermore, we suggest that mechanical stress such as stretch induces activation and down-regulation of PKC a in caveolae.3) Discussion and future development :The present results suggest that tyrosine kinase such as src family and PKC a and d isoforms assembles in caveolae and play a regulatory role in the expression of biological function such as contraction. We will improve the methods of immunocytochemical in situ detection and immunoprecipitation in the cardiovascular system. We will also develop a new pharmacological study aiming to detect simultaneously biological function and molecular dynamics in situ. Less