Regulation of autophagy by extracellular signal-regulated protein kinases during 1-methyl-4-phenylpyridinium-induced cell death
Regulation of autophagy by extracellular signal-regulated protein kinases during 1-methyl-4-phenylpyridinium-induced cell death
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DOI：
10.2353/ajpath.2007.060524
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发表时间：
2007-01-01
影响因子：
6
通讯作者：
Chu, Charleen T.
中科院分区：
文献类型：
--
作者：
Zhu, Jian-hui;Horbinski, Craig;Chu, Charleen T.
在发育和病理情况下，损伤或退化的神经元中都会出现自噬空泡（AV）增加。虽然饥饿诱导的自噬的调控已被广泛研究，但对病理损伤的自噬反应知之甚少。神经毒素1-甲基-4-苯基吡啶鎓（MPP+）可产生靶向神经损伤，导致1-甲基-4-苯基-1，2，3，6-四氢吡啶诱发的帕金森病。在这里，我们证明MPP+引起增加SH-SY 5 Y细胞中的自噬，通过电子显微镜，免疫荧光自噬蛋白LC 3/Atg 8，LC 3电泳迁移率的变化，线粒体降解，和monodansylcadarine染色晚期AV/autolysosomes评估。在营养缺乏期间，III类磷脂酰肌醇-3激酶（PI 3 K）与自噬调节蛋白beclin 1/Atg 6协同刺激自噬。虽然PI 3 K抑制剂和RNA干扰敲低beclin 1有效地抑制了由氨基酸剥夺引起的自噬，但两者都没有降低MPP+诱导的自噬应激。与此相反，抑制丝裂原活化蛋白激酶/细胞外信号调节蛋白激酶激酶降低AV含量，线粒体降解，MPP+处理的细胞中的细胞死亡。针对核心Atg蛋白的RNA干扰研究也降低了AV含量和细胞死亡。同样，在原代中脑多巴胺能神经元中，MPP+引起AV含量增加，这可通过抑制丝裂原活化蛋白激酶/细胞外信号调节蛋白激酶激酶而不是PI 3 K来逆转。这些结果暗示了MPP+引起的自噬应激的细胞外信号调节蛋白激酶（ERK）信号上游的作用。此外，非beclin 1依赖性自噬的病理刺激与神经元细胞死亡相关。
Increased autophagic vacuoles (AVs) occur in injured or degenerating neurons, under both developmental and pathological situations. Although regulation of starvation-induced autophagy has been extensively studied, less is known about autophagic responses to pathological damage. The neurotoxin 1-methyl-4-phenylpyridinium (MPP+) produces mitochondria-targeted injury, which contributes to parkinsonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine in mammals. Here, we demonstrate that MPP+ elicited increased autophagy in SH-SY5Y cells, as assessed by electron microscopy, immunofluorescence for the autophagy protein LC3/Atg8, LC3 electrophoretic mobility shift, mitochondrial degradation, and monodansylcadaverine staining for late AVs/autolysosomes. During nutrient deprivation, class III phosphatidylinositol-3 kinase (PI3K) stimulates autophagy in concert with the autophagy-regulatory protein beclin 1/Atg6. Although PI3K inhibitors and RNA interference knockdown of beclin 1 effectively inhibited autophagy elicited by amino acid deprivation, neither reduced MPP+-induced autophagic stress. In contrast, inhibition of mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase reduced AV content, mitochondrial degradation, and cell death in MPP+-treated cells. RNA interference studies targeting core Atg proteins also reduced AV content and cell death. Likewise, in primary midbrain dopaminergic neurons, MPP+ elicited increased AV content, which was reversed by inhibition of mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase but not PI3K. These results implicate a role for extracellular signal-regulated protein kinase (ERK) signaling upstream of MPP+-elicited autophagic stress. Moreover, pathological stimulation of beclin 1-independent autophagy is associated with neuronal cell death.