Survival function of ERK1/2 as IL-3-activated, staurosporine-resistant Bcl2 kinases
Survival function of ERK1/2 as IL-3-activated, staurosporine-resistant Bcl2 kinases
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DOI：
10.1073/pnas.97.4.1578
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发表时间：
2000-02-15
影响因子：
11.1
通讯作者：
May, WS
中科院分区：
文献类型：
--
作者：
Deng, XM;Ruvolo, P;May, WS
Bcl2 在 Ser-70 位点的磷酸化可能是完全有效抑制 IL-3 依赖性骨髓细胞凋亡所必需的，并且可能是线粒体蛋白激酶 C (PKC) 激动剂激活的结果。矛盾的是，外源 Bcl2 的表达可以保护亲代细胞免受强效 PKC 抑制剂星形孢菌素 (stauro) 诱导的细胞凋亡。在体外，高达 1 μM 的高浓度 stauro 仅部分抑制 IL-3 刺激的 Bcl2 磷酸化，但完全阻断 PKC 介导的 Bcl2 磷酸化。这些数据表明了 stauro 抗性 Bcl2 激酶 (SRK) 的作用。我们发现，金精三羧酸 (ATA) 是细胞 MEK/丝裂原激活蛋白激酶 (MAPK) 激酶的非肽激活剂，可以诱导 Bcl2 Ser-70 磷酸化，并支持表达野生型而非磷酸化无能的 S70A 突变体 Bcl2 的细胞存活。 MEK/MAPK 作为负责任的 SRK 的作用受到牵连，因为高度特异性的 MEK/MAPK 抑制剂 PD98059 也只能部分抑制 IL-3 诱导的 Bcl2 磷酸化，而 PD98059 和 stauro 的组合完全阻断磷酸化并协同增强细胞凋亡。 p44MAPK/细胞外信号调节激酶 1 (ERK1) 和 p42 MAPK/ERK2 被 IL-3 激活，与线粒体 Bcl2 共定位，并且可以在体外和体内以 stauro 抗性方式直接磷酸化 Ser-70 上的 Bcl2。这些发现表明 ERK1/2 激酶与 SRK 一样发挥作用，因此，SRK 可以在功能上连接 IL-3 刺激的增殖和生存信号通路，并以一种新的能力解释 Bcl2 如何抑制 stauro 诱导的细胞凋亡。此外，虽然磷酸化调节Bcl2的机制尚不清楚，但我们的结果表明磷酸化可能在功能上稳定Bcl2-Bax异二聚化。
Bcl2 phosphorylation at Ser-70 may be required for the full and potent suppression of apoptosis in IL-3-dependent myeloid cells and can result from agonist activation of mitochondrial protein kinase C (PKC). Paradoxically, expression of exogenous Bcl2 can protect parental cells from apoptosis induced by the potent PKC inhibitor, staurosporine (stauro). High concentrations of stauro of up to 1 mu M only partially inhibit IL-3-stimulated Bcl2 phosphorylation but completely block PKC-mediated Bcl2 phosphorylation in vitro. These data indicate a role for a stauro-resistant Bcl2 kinase (SRK). We show that aurintricarboxylic acid (ATA), a nonpeptide activator of cellular MEK/mitogen-activated protein kinase (MAPK) kinase, can induce Ser-70 phosphorylation of Bcl2 and support survival of cells expressing wild-type but not the phosphorylation-incompetent S70A mutant Bcl2. A role for a MEK/MAPK as a responsible SRK was implicated because the highly specific MEK/MAPK inhibitor, PD98059, also can only partially inhibit IL-3-induced Bcl2 phosphorylation, whereas the combination of PD98059 and stauro completely blocks phosphorylation and synergistically enhances apoptosis. p44MAPK/extracellular signal-regulated kinase 1 (ERK1) and p42 MAPK/ERK2 are activated by IL-3, colocalize with mitochondrial Bcl2, and can directly phosphorylate Bcl2 on Ser-70 in a stauro-resistant manner both in vitro and in vivo. These findings suggest a role for the ERK1/2 kinases as SRKs, Thus, the SRKs can serve to functionally link the IL-3-stimulated proliferative and survival signaling pathways and, in a novel capacity, may explain how Bcl2 can suppress stauro-induced apoptosis. In addition, although the mechanism of regulation of Bcl2 by phosphorylation is not yet clear, our results indicate that phosphorylation may functionally stabilize the Bcl2-Bax heterodimerization.