Leukemia Inhibitory Factor Activates Cardiac L-Type Ca2+ Channels via Phosphorylation of Serine 1829 in the Rabbit Cav1.2 Subunit
Leukemia Inhibitory Factor Activates Cardiac L-Type Ca2+ Channels via Phosphorylation of Serine 1829 in the Rabbit Cav1.2 Subunit
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DOI：
10.1161/01.res.0000126405.38858.bc
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发表时间：
2004-05
期刊：
影响因子：
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通讯作者：
E. Takahashi;K. Fukuda;S. Miyoshi;M. Murata;Takahiro Kato;M. Ita;T. Tanabe;S. Ogawa
中科院分区：
文献类型：
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作者：
E. Takahashi;K. Fukuda;S. Miyoshi;M. Murata;Takahiro Kato;M. Ita;T. Tanabe;S. Ogawa
我们之前报道过，白血病抑制因子（LIF）逐渐增加心脏l型Ca2+通道电流（ICaL），在成年和新生大鼠心肌细胞中，ICaL在15分钟达到峰值，这种增加被丝裂原激活的蛋白激酶激酶抑制剂PD98059阻断。本研究探讨了liff诱导的啮齿动物心肌细胞ICaL增强的分子基础。LIF诱导培养的大鼠心肌细胞l型Ca2+通道α1c亚基（Cav1.2）的丝氨酸残基磷酸化，PD98059抑制这种磷酸化。当将编码野生型或羧基末端截断的兔Cav1.2亚基的构建物转染到HEK293细胞时，LIF诱导了野生型蛋白的磷酸化，而不是突变蛋白的磷酸化。在没有LIF刺激的情况下，共转染具有组成性活性的丝裂原活化蛋白激酶激酶也会导致Cav1.2亚基的磷酸化。在ingel激酶试验中，细胞外信号调节激酶磷酸化Cav1.2的羧基末端谷胱甘肽s -转移酶融合蛋白（残基1700至1923），该蛋白包含一致的序列Pro-Leu-Ser-Pro。这个一致序列中的一个点突变，导致残基1829 （S1829A）上的丝氨酸被丙氨酸取代，足以消除liff诱导的磷酸化。在转染了野生型Cav1.2的HEK细胞中，LIF增加了ICaL，而转染了突变型Cav1.2的HEK细胞没有增加ICaL。这些结果提供了直接证据，证明LIF通过细胞外信号调节激酶的作用使Cav1.2亚基1829位的丝氨酸残基磷酸化，并且这种磷酸化增加了心肌细胞的ICaL。
We have previously reported that leukemia inhibitory factor (LIF) gradually increased cardiac L-type Ca2+ channel current (ICaL), which peaked at 15 minutes in both adult and neonatal rat cardiomyocytes, and this increase was blocked by the mitogen-activated protein kinase kinase inhibitor PD98059. This study investigated the molecular basis of LIF-induced augmentation of ICaL in rodent cardiomyocytes. LIF induced phosphorylation of a serine residue in the α1c subunit (Cav1.2) of L-type Ca2+ channels in cultured rat cardiomyocytes, and this phosphorylation was inhibited by PD98059. When constructs encoding either a wild-type or a carboxyl-terminal–truncated rabbit Cav1.2 subunit were transfected into HEK293 cells, LIF induced phosphorylation of the resultant wild-type protein but not the mutant protein. Cotransfection of constitutively active mitogen-activated protein kinase kinase also resulted in phosphorylation of the Cav1.2 subunit in the absence of LIF stimulation. In ingel kinase assays, extracellular signal–regulated kinase phosphorylated a glutathione S-transferase fusion protein of the carboxyl-terminal region of Cav1.2 (residues 1700 through 1923), which contains the consensus sequence Pro-Leu-Ser-Pro. A point mutation within this consensus sequence, which results in a substitution of alanine for serine at residue 1829 (S1829A), was sufficient to abolish the LIF-induced phosphorylation. LIF increased ICaL in HEK cells transfected with wild-type Cav1.2 but not with the mutated version. These results provide direct evidence that LIF phosphorylates the serine residue at position 1829 of the Cav1.2 subunit via the actions of extracellular signal–regulated kinase and that this phosphorylation increases ICaL in cardiomyocytes.