Beclin 1-independent autophagy contributes to apoptosis in cortical neurons
Beclin 1-independent autophagy contributes to apoptosis in cortical neurons
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DOI：
10.4161/auto.7.10.16608
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发表时间：
2011-10-01
期刊：
影响因子：
13.3
通讯作者：
Puyal, Julien
中科院分区：
文献类型：
--
作者：
Grishchuk, Yulia;Ginet, Vanessa;Puyal, Julien
神经元自噬在许多神经系统疾病中增强，如脑缺血和创伤性脑损伤，但其在相关神经元死亡中的作用存在争议，特别是在细胞凋亡的情况下。因此，我们研究了自噬在初代皮质神经元凋亡中的作用，这些神经元被广泛使用的强效促凋亡药物staurosporine （STS）处理。甚至在细胞凋亡之前，STS也增强了自噬通量，如自噬体（LC3- ii水平，LC3点状标记）和溶酶体（组织蛋白酶D， LAMP1，酸性磷酸酶，β -己糖苷酶）标记物的增加所示。通过3-甲基腺嘌呤或慢病毒递送的针对Atg5和Atg7的shrna抑制自噬，可显著降低sts诱导的caspase-3激活和AIF核易位，并对神经元死亡提供部分保护。用Q-VD-OPH抑制Pan-caspase同样可以部分防止神经元死亡，但不能影响自噬。自噬和半胱天冬酶的联合抑制具有很强的协同神经保护作用。导致细胞凋亡的自噬是不依赖于Beclin - 1的，Beclin - 1敲低不能降低Beclin - 1，但能有效地降低雷帕霉素诱导的自噬。此外，Beclin 1敲低使神经元对sts诱导的凋亡敏感，表明Beclin 1在皮质神经元中具有细胞保护作用。另外两种促凋亡刺激（MK801和依托oposide）诱导的Caspase-3激活和固缩同样与Beclin - 1不依赖的自噬有关，并且通过敲低Atg7而不是Beclin - 1而减少。综上所述，Beclin - 1非依赖性自噬是caspase依赖性和非依赖性神经元凋亡的重要组成部分，可能被认为是涉及细胞凋亡的神经疾病的重要治疗靶点。
Neuronal autophagy is enhanced in many neurological conditions, such as cerebral ischemia and traumatic brain injury, but its role in associated neuronal death is controversial, especially under conditions of apoptosis. We therefore investigated the role of autophagy in the apoptosis of primary cortical neurons treated with the widely used and potent pro-apoptotic agent, staurosporine (STS). Even before apoptosis, STS enhanced autophagic flux, as shown by increases in autophagosomal (LC3-II level, LC3 punctate labeling) and lysosomal (cathepsin D, LAMP1, acid phosphatase, beta-hexasominidase) markers. Inhibition of autophagy by 3-methyladenine, or by lentivirally-delivered shRNAs against Atg5 and Atg7, strongly reduced the STS-induced activation of caspase-3 and nuclear translocation of AIF, and gave partial protection against neuronal death. Pan-caspase inhibition with Q-VD-OPH likewise protected partially against neuronal death, but failed to affect autophagy. Combined inhibition of both autophagy and caspases gave strong synergistic neuroprotection. The autophagy contributing to apoptosis was Beclin 1-independent, as shown by the fact that Beclin 1 knockdown failed to reduce it but efficiently reduced rapamycin-induced autophagy. Moreover the Beclin 1 knockdown sensitized neurons to STS-induced apoptosis, indicating a cytoprotective role of Beclin 1 in cortical neurons. Caspase-3 activation and pyknosis induced by two other pro-apoptotic stimuli, MK801 and etoposide, were likewise found to be associated with Beclin 1-independent autophagy and reduced by the knockdown of Atg7 but not Beclin 1. In conclusion, Beclin 1-independent autophagy is an important contributor to both the caspase-dependent and -independent components of neuronal apoptosis and may be considered as an important therapeutic target in neural conditions involving apoptosis.