Trophic factor withdrawal: p38 mitogen-activated protein kinase activates NHE1, which induces intracellular alkalinization
Trophic factor withdrawal: p38 mitogen-activated protein kinase activates NHE1, which induces intracellular alkalinization
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DOI：
10.1128/mcb.21.22.7545-7557.2001
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发表时间：
2001-11-01
影响因子：
5.3
通讯作者：
Durum, SK
中科院分区：
文献类型：
--
作者：
Khaled, AR;Moor, AN;Durum, SK
营养因子的撤除会通过尚未完全了解的机制诱导细胞死亡。之前我们报道过白细胞介素 7 (IL-7) 或 IL-3 的退出会导致细胞内快速碱化，破坏线粒体代谢并激活死亡蛋白 Bax。我们现在观察到，这种新的碱化途径是由 pH 调节剂 NHE1 介导的，如对钠的需求、药物抑制剂的阻断或使用 NHE1 缺陷细胞系所示，并且 NHE1 碱化磷酸化的改变也需要应激激活的 p38 丝裂原激活蛋白激酶 (MAPK)。用药理学抑制剂抑制 p38 MAPK 活性或显性失活激酶的表达可防止碱化。激活的 p38 MAPK 直接磷酸化 NHE1 C 末端的 40 个氨基酸区域。质谱分析确定了 NHE1 上的四个磷酸化位点：Thr 717、Ser 722、Ser 725 和 Ser 728。因此，营养细胞因子信号传导的丧失诱导了 p38 MAPK 途径，该途径在特定位点磷酸化 NHE1，从而诱导细胞内碱化。
Trophic factor withdrawal induces cell death by mechanisms that are incompletely understood. Previously we reported that withdrawal of interleukin-7 (IL-7) or IL-3 produced a rapid intracellular alkalinization, disrupting mitochondrial metabolism and activating the death protein Bax. We now observe that this novel alkalinization pathway is mediated by the pH regulator NHE1, as shown by the requirement for sodium, blocking by pharmacological inhibitors or use of an NHE1-deficient cell line, and the altered phosphorylation of NHE1 Alkalinization also required the stress-activated p38 mitogen-activated protein kinase (MAPK). Inhibition of p38 MAPK activity with pharmacological inhibitors or expression of a dominant negative kinase prevented alkalinization. Activated p38 MAPK directly phosphorylated the C terminus of NHE1 within a 40-amino-acid region. Analysis by mass spectroscopy identified four phosphorylation sites on NHE1, Thr 717, Ser 722, Ser 725, and Ser 728. Thus, loss of trophic cytokine signaling induced the p38 MAPK pathway, which phosphorylated NHE1 at specific sites, inducing intracellular alkalinization.