线粒体酸 5 通过增加 Bnip3 相关的线粒体自噬来激活 MAPK-ERK-yap 信号通路，从而保护小鼠小神经胶质细胞 BV-2 细胞免受 TNFα 诱导的凋亡。

Mitochonic acid 5 activates the MAPK-ERK-yap signaling pathways to protect mouse microglial BV-2 cells against TNFα-induced apoptosis via increased Bnip3-related mitophagy.

机构信息

Department of Neurology, First Hospital Affiliated to University of South China, Hunan, China.

出版信息

Cell Mol Biol Lett. 2018 Apr 5;23:14. doi: 10.1186/s11658-018-0081-5. eCollection 2018.

BACKGROUND

The regulation of microglial function via mitochondrial homeostasis is important in the development of neuroinflammation. The underlying mechanism for this regulatory function remains unclear. In this study, we investigated the protective role of mitochonic acid 5 (MA-5) in microglial mitochondrial apoptosis following TNFα-induced inflammatory injury.

METHODS

TNFα was used to induce inflammatory injury in mouse microglial BV-2 cells with and without prior MA-5 treatment. Cellular apoptosis was assessed using the MTT and TUNEL assays. Mitochondrial functions were evaluated via mitochondrial membrane potential JC-1 staining, ROS flow cytometry analysis, mPTP opening assessment, and immunofluorescence of cyt-c. Mitophagy was examined using western blots and immunofluorescence. The pathways analysis was carried out using western blots and immunofluorescence with a pathway blocker.

RESULTS

Our results demonstrated that TNFα induced apoptosis in the microglial BV-2 cell line by activating the caspase-9-dependent mitochondrial apoptotic pathway. Mechanistically, inflammation reduced mitochondrial potential, induced ROS production, and contributed to the leakage of mitochondrial pro-apoptotic factors into the cytoplasm. The inflammatory response reduced cellular energy metabolism and increased oxidative stress. By contrast, treatment with MA-5 reduced mitochondrial apoptosis via upregulation of mitophagy. Increased mitophagy degraded damaged mitochondria, disrupting mitochondrial apoptosis, neutralizing ROS overproduction, and improving cellular energy production. We also identified that MA-5 regulated mitophagy via Bnip3 through the MAPK-ERK-Yap signaling pathway. Inhibiting this signaling pathway or knocking down Bnip3 expression prevented MA-5 from having beneficial effects on mitochondrial homeostasis and increased microglial apoptosis.

CONCLUSIONS

After TNFα-induced inflammatory injury, MA-5 affects microglial mitochondrial homeostasis in a manner mediated via the amplification of protective, Bnip3-related mitophagy, which is mediated via the MAPK-ERK-Yap signaling pathway.

背景

通过线粒体稳态调节小胶质细胞功能对于神经炎症的发展很重要。这种调节功能的潜在机制尚不清楚。在这项研究中，我们研究了 MA-5 在 TNFα 诱导的炎症损伤后小胶质细胞线粒体凋亡中的保护作用。

方法

用 TNFα 诱导有和没有 MA-5 预处理的小鼠小胶质细胞 BV-2 细胞发生炎症损伤。用 MTT 和 TUNEL 测定评估细胞凋亡。通过 JC-1 染色、ROS 流式细胞术分析、mPTP 开放评估和细胞色素 c 的免疫荧光检测评估线粒体功能。用 Western blot 和免疫荧光检测自噬。用 Western blot 和免疫荧光与通路阻断剂进行通路分析。

结果

我们的结果表明，TNFα 通过激活 caspase-9 依赖性线粒体凋亡途径诱导小胶质细胞 BV-2 细胞系凋亡。机制上，炎症降低线粒体电位，诱导 ROS 产生，并导致线粒体促凋亡因子漏入细胞质。炎症反应降低细胞能量代谢并增加氧化应激。相比之下，用 MA-5 处理可通过上调自噬减少线粒体凋亡。增加的自噬降解受损的线粒体，阻断线粒体凋亡，中和 ROS 过度产生，并改善细胞能量产生。我们还发现，MA-5 通过 MAPK-ERK-Yap 信号通路调节自噬，通过 Bnip3。抑制这条信号通路或敲低 Bnip3 表达可阻止 MA-5 对线粒体稳态产生有益影响并增加小胶质细胞凋亡。