CaMKII negatively regulates calcineurin-NFAT signaling in cardiac myocytes.
CaMKII negatively regulates calcineurin-NFAT signaling in cardiac myocytes.
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DOI：
10.1161/circresaha.109.194035
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发表时间：
2009-08-14
影响因子：
20.1
通讯作者：
Houser SR
中科院分区：
文献类型：
--
作者：
MacDonnell SM;Weisser-Thomas J;Kubo H;Hanscome M;Liu Q;Jaleel N;Berretta R;Chen X;Brown JH;Sabri AK;Molkentin JD;Houser SR
病理性心肌细胞肥大被认为是由收缩期壁应力增加时维持心脏功能所需的细胞内Ca 2+持续增加引起的。肥大性Ca 2+与钙调蛋白（CaM）结合并激活磷酸酶钙调神经磷酸酶（Cn）和CaM激酶（CaMKII）。Cn使活化T细胞的胞质核因子（NFAT）去磷酸化，诱导其易位至细胞核，在细胞核中其活化抗凋亡和肥大靶基因。胞质CaMKII调节Ca 2+处理蛋白，但它是否直接参与肥大和存活信号转导尚不清楚。本研究探讨了细胞质CaMK Ⅱ通过抑制Cn的磷酸酶活性减少NFAT核转位的假说。用GFP标记的NFATc 3在培养的新生大鼠心室肌细胞（NRVM）和成年猫心室肌细胞中定位。细胞质靶向CaMKIIδc的组成型活性（CaMKII-CA）或显性失活（CaMKII-DN）突变体用于激活和抑制细胞质CaMKII活性。NRVM组CaMKII-DN增加（48.5± 3%，P<0.01），CaMKII-CA减少（5.9± 1%，P<0.01），NFAT核转位减少（12.3±1%，P <0.01）。使用Cn抑制剂来表明这些效应是由Cn活性的调节引起的。增加Ca 2+增加Cn依赖性NFAT易位（至71.7± 7%，p<0.01），CaMKII-CA降低这种作用（至17.6±4%）。CaMKII-CA可增加TUNEL和caspase-3活性（P<0.05）。在CaMKII-CA感染的NRVM和肥大的猫心脏中，CaMKII直接磷酸化Cn的Ser 197。这些数据表明，细胞质CaMKII的活化通过磷酸化和随后的Cn抑制来抑制NFAT核转位。
Pathologic cardiac myocyte hypertrophy is thought to be induced by the persistent increases in intracellular Ca2+ needed to maintain cardiac function when systolic wall stress is increased. Hypertrophic Ca2+ binds to calmodulin (CaM) and activates the phosphatase calcineurin (Cn) and CaM kinase (CaMKII). Cn dephosphorylates cytoplasmic nuclear factor of activated T-cells (NFAT), inducing its translocation to the nucleus where it activates anti-apoptotic and hypertrophic target genes. Cytoplasmic CaMKII regulates Ca2+ handling proteins but whether or not it is directly involved in hypertrophic and survival signaling is not known. This study explored the hypothesis that cytoplasmic CaMKII reduces NFAT nuclear translocation by inhibiting the phosphatase activity of Cn. GFP-tagged NFATc3 was used to determine the cellular location of NFAT in cultured neonatal rat ventricular myocytes (NRVM) and adult feline ventricular myocytes. Constitutively active (CaMKII-CA) or dominant negative (CaMKII-DN) mutants of cytoplasmic targeted CaMKIIδc were used to activate and inhibit cytoplasmic CaMKII activity. In NRVM CaMKII-DN (48.5±3%, P<0.01 vs control) increased while CaMKII-CA decreased (5.9±1%, P<0.01 vs control) NFAT nuclear translocation (Control: 12.3±1%). Cn inhibitors were used to show that these effects were caused by modulation of Cn activity. Increasing Ca2+ increased Cn-dependent NFAT translocation (to 71.7±7%, p<0.01) and CaMKII-CA reduced this effect (to 17.6±4%). CaMKII-CA increased TUNEL and caspase-3 activity (P<0.05). CaMKII directly phosphorylated Cn at Ser197 in CaMKII-CA infected NRVM and in hypertrophied feline hearts. These data show that activation of cytoplasmic CaMKII inhibits NFAT nuclear translocation by phosphorylation and subsequent inhibition of Cn.