小胶质细胞 PGC-1α 通过抑制神经炎症来保护缺血性脑损伤。

Microglial PGC-1α protects against ischemic brain injury by suppressing neuroinflammation.

机构信息

Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China.

Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China.

出版信息

Genome Med. 2021 Mar 26;13(1):47. doi: 10.1186/s13073-021-00863-5.

DOI:10.1186/s13073-021-00863-5

PMID:33771213

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8004413/

Abstract

BACKGROUND

Neuroinflammation and immune responses occurring minutes to hours after stroke are associated with brain injury after acute ischemic stroke (AIS). PPARγ coactivator-1α (PGC-1α), as a master coregulator of gene expression in mitochondrial biogenesis, was found to be transiently upregulated in microglia after AIS. However, the role of microglial PGC-1α in poststroke immune modulation remains unknown.

METHODS

PGC-1α expression in microglia from human and mouse brain samples following ischemic stroke was first determined. Subsequently, we employed transgenic mice with microglia-specific overexpression of PGC-1α for middle cerebral artery occlusion (MCAO). The morphology and gene expression profile of microglia with PGC-1α overexpression were evaluated. Downstream inflammatory cytokine production and NLRP3 activation were also determined. ChIP-Seq analysis was performed to detect PGC-1α-binding sites in microglia. Autophagic and mitophagic activity was further monitored by immunofluorescence staining. Unc-51-like autophagy activating kinase 1 (ULK1) expression was evaluated under the PGC-1α interaction with ERRα. Finally, pharmacological inhibition and genomic knockdown of ULK1 were performed to estimate the role of ULK1 in mediating mitophagic activity after ischemic stroke.

RESULTS

PGC-1α expression was shortly increased after ischemic stroke, not only in human brain samples but also in mouse brain samples. Microglia-specific PGC-1α overexpressing mice exhibited significantly decreased neurologic deficits after ischemic injury, with reduced NLRP3 activation and proinflammatory cytokine production. ChIP-Seq analysis and KEGG pathway analysis revealed that mitophagy was significantly enhanced. PGC-1α significantly promoted autophagic flux and induced autolysosome formation. More specifically, the autophagic clearance of mitochondria was enhanced by PGC-1α regulation, indicating the important role of mitophagy. Pharmacological inhibition or knockdown of ULK1 expression impaired autophagic/mitophagic activity, thus abolishing the neuroprotective effects of PGC-1α.

CONCLUSIONS

Mechanistically, in AIS, PGC-1α promotes autophagy and mitophagy through ULK1 and reduces NLRP3 activation. Our findings indicate that microglial PGC-1α may be a promising therapeutic target for AIS.

摘要

背景

中风后数分钟至数小时发生的神经炎症和免疫反应与急性缺血性中风（AIS）后的脑损伤有关。过氧化物酶体增殖物激活受体γ共激活因子 1α（PGC-1α）作为线粒体生物发生中基因表达的主要调控因子，在 AIS 后小胶质细胞中被发现短暂上调。然而，小胶质细胞 PGC-1α 在中风后免疫调节中的作用尚不清楚。

方法

首先确定人及鼠脑样本中风后小胶质细胞中 PGC-1α 的表达。随后，我们使用小胶质细胞特异性过表达 PGC-1α 的转基因小鼠进行大脑中动脉闭塞（MCAO）。评估过表达 PGC-1α 的小胶质细胞的形态和基因表达谱。还测定了下游炎性细胞因子的产生和 NLRP3 的激活。进行 ChIP-Seq 分析以检测小胶质细胞中 PGC-1α 的结合位点。通过免疫荧光染色进一步监测自噬和线粒体自噬活性。通过 PGC-1α 与 ERRα 的相互作用评估 UNC-51 样自噬激活激酶 1（ULK1）的表达。最后，进行 ULK1 的药理学抑制和基因敲低，以估计 ULK1 在介导中风后线粒体自噬活性中的作用。

结果

PGC-1α 在中风后短时间内增加，不仅在人类脑样本中，而且在鼠脑样本中也是如此。小胶质细胞特异性过表达 PGC-1α 的小鼠在缺血性损伤后神经功能缺损明显减少，NLRP3 激活和促炎细胞因子产生减少。ChIP-Seq 分析和 KEGG 通路分析显示线粒体自噬明显增强。PGC-1α 显著促进自噬流并诱导自噬溶酶体形成。更具体地说，PGC-1α 调节增强了线粒体的自噬清除，表明线粒体自噬的重要作用。ULK1 表达的药理学抑制或敲低损害了自噬/线粒体自噬活性，从而消除了 PGC-1α 的神经保护作用。