Role of calcineurin and protein phosphatase-2A in the regulation of phosphatase inhibitor-1 in cardiac myocytes
Role of calcineurin and protein phosphatase-2A in the regulation of phosphatase inhibitor-1 in cardiac myocytes
复制标题
DOI：
10.1016/j.bbrc.2006.05.182
复制
发表时间：
2006-08-04
影响因子：
3.1
通讯作者：
Eschenhagen, Thomas
中科院分区：
文献类型：
--
作者：
El-Armouche, Ali;Bednorz, Anna;Eschenhagen, Thomas
抑制剂1（I-1）是蛋白磷酸酶1（PP 1）的蛋白抑制剂，蛋白磷酸酶1是心脏中主要的Ser-Thr磷酸酶。非磷酸化的I-1是无活性的，而在Thr 35处被蛋白激酶A（PKA）磷酸化的I-1是有效的PP 1抑制剂。使I-1 Thr 35去磷酸化从而使心脏中的I-1失活的磷酸酶尚未建立。在这里，我们过表达的I-1在新生大鼠心肌细胞与重组腺病毒和测定磷酸化的I-1，和PKA/PP 1的主要靶蛋白之一，在心脏，受磷蛋白（PLB），通过蛋白质印迹与磷酸化特异性抗体。与钙调磷酸酶抑制剂环孢素A或冈田酸（以优先抑制磷酸酶2A（PP 2A）的浓度使用）孵育，显著增加I-1 Thr 35（类似于2至6倍）和PLB Ser 16磷酸化（类似于2倍）。结果表明，钙调神经磷酸酶和PP 2A的作用，以维持低水平的磷酸化（活性）I-1在活心肌细胞的基础。钙调神经磷酸酶可能构成钙依赖性途径和cAMP依赖性途径之间的串扰。(c)2006年爱思唯尔公司All rights reserved.
Inhibitor 1 (I-1) is a protein inhibitor of protein phosphatase 1 (PP1), the predominating Ser/Thr phosphatase in the heart. Non-phosphorylated I-1 is inactive, whereas I-1 phosphorylated by protein kinase A (PKA) at Thr35 is a potent PP1 inhibitor. The phosphatases that dephosphorylate I-1Thr35 and thus deactivate I-1 in the heart are not established. Here we overexpressed I-1 in neonatal rat cardiac myocytes with recombinant adenovirus and determined phosphorylation of I-1, and one of the major target proteins of PKA/PP1 in the heart, phospholamban (PLB), by Western blot with phospho-specific antibodies. Incubation with the calcineurin inhibitor cyclosporine A or okadaic acid, used at a concentration preferentially inhibiting phosphatase 2A (PP2A), increased significantly I-1Thr35 (similar to 2- to 6-fold) and PLB Ser16 phosphorylation (similar to 2-fold). The results indicate that calcineurin and PP2A act to maintain a low basal level of phosphorylated (active) I-1 in living cardiac myocytes. Calcineurin may constitute a cross-talk between calcium- and cAMP-dependent pathways. (c) 2006 Elsevier Inc. All rights reserved.