Membrane depolarization-mediated survival of sympathetic neurons occurs through both phosphatidylinositol 3-kinase- and CaM kinase II-dependent pathways
Membrane depolarization-mediated survival of sympathetic neurons occurs through both phosphatidylinositol 3-kinase- and CaM kinase II-dependent pathways
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DOI：
10.1016/s0006-8993(00)02284-8
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发表时间：
2000-06-02
期刊：
影响因子：
2.9
通讯作者：
Koike, T
中科院分区：
文献类型：
--
作者：
Ikegami, K;Koike, T
已经确定的是，NGF介导的交感神经元在培养物中的存活通过磷脂酰肌醇（PI）3-激酶/Akt依赖性途径发生。与此相反，膜去极化促进神经元存活独立的神经生长因子的机制仍然没有得到解决。在这里，我们表明，LY 294002，PI 3-激酶的特异性抑制剂，诱导细胞死亡的交感神经元去极化条件下升高K-（IC 50 =类似于30 μ M）有趣的是，较低浓度的这种药物（小于或等于10 μ M）足以抑制Akt磷酸化丝氨酸-473，一个假定的PI 3-激酶的下游目标，在这些条件下。我们还表明，KN-62，钙/钙调蛋白依赖性蛋白激酶II（CaMKII）的特异性抑制剂抑制去极化介导的生存在剂量依赖性的方式（IC 50 =类似2 μ M），抑制衰减的持续水平的细胞内Ca 2+诱发的去极化。该IC 50值大于CaMKII的IC 50值（类似于0.8 μ M）。这些发现使我们假设去极化介导的存活通过PI 3-激酶/Akt和CaMKII途径发生。事实上，LY 294002（25 μ M）和KN-62（0.5 μ M）的联合治疗显着消除去极化介导的生存，而每一个单独没有显着减弱it. Under这些条件下，KN-62既不损害细胞内Ca 2+的持续水平，也不抑制Akt的磷酸化。因此，PI 3-激酶和CaMKII可能独立地促进培养中交感神经元的膜去极化介导的存活。(C)2000 Elsevier Science B. V.保留所有权利。
It has been well established that the NGF-mediated survival of sympathetic neurons in culture occurs through the phosphatidylinositol (PI) 3-kinase/Akt-dependent pathway. In contrast, the mechanism by which membrane depolarization promotes neuronal survival independently of NGF remains unresolved. Here we show that LY294002, a specific inhibitor of PI 3-kinase, induced cell death of sympathetic neurons under depolarizing conditions with elevated K- (IC50=similar to 30 mu M) Interestingly, lower concentrations of this agent (less than or equal to 10 mu M) were sufficient to suppress Akt phosphorylation at Ser-473, a putative downstream target of PI 3-kinase, under these conditions. We also show that KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII) suppressed depolarization-mediated survival in a does-dependent manner (IC50=similar to 2 mu M) that paralleled attenuation of sustained levels of intracellular Ca2+ evoked by depolarization. This IC50 value is greater than that for CaMKII (similar to 0.8 mu M). These findings led us to hypothesize that depolarization-mediated survival occurs through both the PI 3-kinase/Akt and the CaMKII pathways. Indeed, combined treatment with LY294002 (25 mu M) and KN-62 (0.5 mu M) dramatically abolished depolarization-mediated survival, whereas each alone did not significantly attenuate it. Under these conditions, KN-62 neither impaired sustained levels of intracellular Ca2+, nor inhibited the phosphorylation of Akt. It is thus likely that PI 3-kinase and CaMKII independently promote the membrane depolarization-mediated survival of sympathetic neurons in culture. (C) 2000 Elsevier Science B.V. All rights reserved.