Regulation of muscle creatine kinase by phosphorylation in normal and diabetic hearts
Regulation of muscle creatine kinase by phosphorylation in normal and diabetic hearts
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DOI：
10.1007/s00018-008-8575-3
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发表时间：
2009-01-01
影响因子：
8
通讯作者：
MacLeod, K. M.
中科院分区：
文献类型：
--
作者：
Lin, G.;Liu, Y.;MacLeod, K. M.
蛋白激酶C(PKC)是心脏中重要的信号分子，但其作用靶点尚不清楚。使用PKC底物抗体，我们检测到一种40 kDa的磷酸化心肌蛋白，随后通过串联质谱仪鉴定为丝氨酸128处具有磷酸化的肌肉肌酸激酶(M-CK)。免疫沉淀的M-CK被蛋白磷酸酶2A(PP2A)或PP2C去磷酸化后，利用ATP生成磷酸肌酸的正向反应减少，而利用磷酸肌酸生成ATP的反向反应增加。尽管糖尿病心脏中PKC水平较高，但M-CK磷酸化水平的降低比其表达的降低更为显著。糖尿病患者心脏CK活性的变化与对照心脏M-CK去磷酸化后的变化相似。磷酸化水平的降低可能作为一种代偿机制，将CK活性维持在适当的水平，以促进糖尿病心脏胞浆ATP的再生。
Protein kinase C (PKC) is an important signaling molecule in the heart, but its targets remain unclear. Using a PKC substrate antibody, we detected a 40-kDa phosphorylated cardiac protein that was subsequently identified by tandem mass spectroscopy as muscle creatine kinase (M-CK) with phosphorylation at serine 128. The forward reaction using ATP to generate phosphocreatine was reduced, while the reverse reaction using phosphocreatine to generate ATP was increased following dephosphorylation of immunoprecipitated M-CK with protein phosphatase 2A (PP2A) or PP2C. Despite higher PKC levels in diabetic hearts, decreased phosphorylation of M-CK was more prominent than the reduction in its expression. Changes in CK activity in diabetic hearts were similar to those found following dephosphorylation of M-CK from control hearts. The decrease in phosphorylation may act as a compensatory mechanism to maintain CK activity at an appropriate level for cytosolic ATP regeneration in the diabetic heart.