Carranza M L, Féraille E, Favre H
Division de Néphrologie, Hôpital Cantonal Universitaire, Geneva, Switzerland.
Am J Physiol. 1996 Jul;271(1 Pt 1):C136-43. doi: 10.1152/ajpcell.1996.271.1.C136.
We have previously shown that, in oxygenated rat kidney proximal convoluted tubules (PCT), activation of protein kinase C (PKC) by phorbol 12,13-dibutyrate (PDBu) directly stimulates Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity. PKC modulation of Na(+)-K(+)-ATPase activity by phosphorylation of its alpha-subunit was the postulated mechanism. The present study was therefore designed to investigate the relationship between PKC-mediated phosphorylation of the catalytic alpha-subunit and the cation transport activity of the Na(+)-K(+)-ATPase. In a suspension of rat kidney cortical tubules, activation of PKC by 10(-7) M PDBu increased the level of phosphorylation of the Na(+)-K(+)-ATPase alpha-subunit and stimulated the ouabain-sensitive 86Rb uptake by 47 and 42%, respectively. Time and dose dependence of the PDBu-induced increase in Na(+)-K(+)-ATPase activity and phosphorylation was strongly linearly correlated. The effects of PDBu on phosphorylation and activity of Na(+)-K(+)-ATPase were prevented by GF-109203X, a specific PKC inhibitor, whereas H-89, a specific PKA inhibitor, was ineffective. These results demonstrate that PKC activation induces phosphorylation of the catalytic alpha-subunit of Na(+)-K(+)-ATPase, which may participate in the stimulation of its cation transport activity in the rat PCT.
我们之前已经表明，在氧合的大鼠肾近端曲管（PCT）中，佛波醇12,13 - 二丁酸酯（PDBu）激活蛋白激酶C（PKC）可直接刺激钠钾腺苷三磷酸酶（ATP酶）的活性。推测其机制是PKC通过磷酸化钠钾ATP酶的α亚基来调节其活性。因此，本研究旨在探讨PKC介导的催化性α亚基磷酸化与钠钾ATP酶阳离子转运活性之间的关系。在大鼠肾皮质小管悬液中，10^(-7) M PDBu激活PKC可使钠钾ATP酶α亚基的磷酸化水平增加，并分别使哇巴因敏感的86Rb摄取量增加47%和42%。PDBu诱导的钠钾ATP酶活性和磷酸化增加的时间和剂量依赖性呈强线性相关。GF - 109203X（一种特异性PKC抑制剂）可阻止PDBu对钠钾ATP酶磷酸化和活性的影响，而特异性PKA抑制剂H - 89则无效。这些结果表明，PKC激活可诱导钠钾ATP酶催化性α亚基的磷酸化，这可能参与刺激大鼠PCT中其阳离子转运活性。
