Regulation of BAD by cAMP-dependent protein kinase is mediated via phosphorylation of a novel site, Ser155
Regulation of BAD by cAMP-dependent protein kinase is mediated via phosphorylation of a novel site, Ser155
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DOI：
10.1042/bj3490547
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发表时间：
2000-07-15
影响因子：
4.1
通讯作者：
Cohen, P
中科院分区：
文献类型：
--
作者：
Lizcano, JM;Morrice, N;Cohen, P
BAD（Bcl-2/Bcl-X-L-拮抗剂，引起细胞死亡）与Bcl-2/Bcl-X-L的相互作用被认为中和后者蛋白的抗凋亡作用，并且可能代表BAD促进凋亡的机制之一。据报道，多种存活信号诱导BAD在Ser（112）或Ser（136）处的磷酸化，触发其从Bcl 2/Bcl-X-L解离。Ser（136）被认为被蛋白激酶B磷酸化蛋白激酶B（PKB，也称为Akt），当细胞暴露于刺激磷脂酰肌醇3-激酶（PI 3 K）的激动剂时，其被激活。相反，据报道，Ser（112）被促分裂原活化蛋白（MAP）激酶活化的蛋白激酶-1磷酸化（MAPKAP-K1，也称为RSK）酸通过cAMP依赖性蛋白激酶（PKA），在这里，我们确定Ser（155）作为BAD上的第三磷酸化位点。我们发现Ser（155）在体外被PKA优先磷酸化，并且是BAD中唯一当细胞暴露于cAMP升高剂时被磷酸化的残基。BAD在Ser（155）处的磷酸化阻止其与Bcl-X-L结合并促进其与14-3-3蛋白的相互作用。我们还提供了进一步的证据表明，MAPKAP-K1介导的丝氨酸（112）的磷酸化响应激动剂，激活经典的MAP激酶途径。然而，胰岛素样生长因子1，一种有效的PI 3 K和PKB激活剂，并不增加NAD转染的HEK-293细胞中Ser（136）的磷酸化，也不通过PI 3 K抑制剂抑制Ser（136）磷酸化的基础水平。
The interaction of BAD (Bcl-2/Bcl-X-L-antagonist, causing cell death) with Bcl-2/Bcl-X-L is thought to neutralize the anti-apoptotic effects of the latter proteins, and may represent one of the mechanisms by which BAD promotes apoptosis. A variety of survival signals are reported to induce the phosphorylation of BAD at Ser(112) or Ser(136), triggering its dissociation from Bcl2/Bcl-X-L. Ser(136) is thought to be phosphorylated by protein kinase B (PKB, also called Akt), which is activated when cells are exposed to agonists that stimulate phosphatidylinositol 3-kinase (PI3K), In contrast, Ser(112) is reported to be phosphorylated by mitogen-activated protein (MAP) kinase-activated protein kinase-1 (MAPKAP-K1, also called RSK) acid by cAMP-dependent protein kinase (PKA), Here we identify Ser(155) as a third phosphorylation site on BAD. We find that Ser(155) is phosphorylated preferentially by PKA in vitro and is the only residue in BAD that becomes phosphorylated when cells are exposed to cAMP-elevating agents. The phosphorylation of BAD at Ser(155) prevents it from binding to Bcl-X-L and promotes its interaction with 14-3-3 proteins. We also provide Further evidence that MAPKAP-K1 mediates the phosphorylation of Ser(112) in response to agonists that activate the classical MAP kinase pathway. However insulin-like growth factor 1, a potent activator of PI3K and PKB does not increase the phosphorylation of Ser(136) in BAD-transfected HEK-293 cells, and nor is the basal level of Ser(136) phosphorylation suppressed by inhibitors of PI3K.