School of Basic Medical Sciences, Anhui Medical University, Hefei, China.
Biopharmaceutical Institute, Anhui Medical University, Hefei, China.
Liver Int. 2021 Mar;41(3):623-639. doi: 10.1111/liv.14697. Epub 2020 Dec 4.
Endoplasmic reticulum (ER) perturbations are novel subcellular effectors involved in the ischaemia-reperfusion injury. As an ER stress-inducible protein, mesencephalic astrocyte-derived neurotrophic factor (MANF) has been proven to be increased during ischaemic brain injury. However, the role of MANF in liver ischaemia reperfusion (I/R) injury has not yet been studied.
To investigate the role of MANF in the process of liver ischaemia-reperfusion, Hepatocyte-specific MANF knockout (MANF ) mice and their wild-type (WT) littermates were used in our research. Mice partial (70%) warm hepatic I/R model was established by vascular occlusion. We detected the serum levels of MANF in both liver transplant patients and WT mice before and after liver I/R injury. Recombinant human MANF (rhMANF) was injected into the tail vein before 1 hour occlusion. AST, ALT and Suzuki score were used to evaluate the extent of I/R injury. OGD/R test was performed on primary hepatocytes to simulate IRI in vitro. RNA sequence and RT-PCR were used to detect the cellular signal pathway activation while MANF knockout.
We found that MANF expression and secretion are dramatically up-regulated during hepatic I/R. Hepatocyte-specific MANF knockout aggravates the I/R injury through the over-activated ER stress. The systemic administration of rhMANF before ischaemia has the potential to ameliorate I/R-triggered UPR and liver injury. Further study showed that MANF deficiency activated ATF4/CHOP and JNK/c-JUN/CHOP pathways, and rhMANF inhibited the activation of the two proapoptotic pathways caused by MANF deletion.
Collectively, our study unravels a previously unknown relationship among MANF, UPR and hepatic I/R injury.
内质网（ER）扰动是一种新的亚细胞效应物，参与缺血再灌注损伤。作为一种 ER 应激诱导蛋白，脑源性神经营养因子（MANF）已被证明在缺血性脑损伤期间增加。然而，MANF 在肝缺血再灌注（I/R）损伤中的作用尚未得到研究。
为了研究 MANF 在肝缺血再灌注过程中的作用，我们使用了肝细胞特异性 MANF 敲除（MANF）小鼠及其野生型（WT）同窝仔鼠。通过血管闭塞建立了小鼠部分（70%）温肝 I/R 模型。我们检测了肝移植患者和 WT 小鼠肝 I/R 损伤前后血清中 MANF 的水平。在闭塞前 1 小时，通过尾静脉注射重组人 MANF（rhMANF）。AST、ALT 和 Suzuki 评分用于评估 I/R 损伤的程度。在体外通过 OGD/R 试验模拟 IRI，以检测原发性肝细胞中细胞信号通路的激活情况。当 MANF 敲除时，使用 RNA 序列和 RT-PCR 检测细胞信号通路的激活。
我们发现，在肝 I/R 期间，MANF 的表达和分泌显著上调。肝细胞特异性 MANF 敲除通过过度激活 ER 应激加重 I/R 损伤。在缺血前系统给予 rhMANF 具有减轻 I/R 触发的 UPR 和肝损伤的潜力。进一步的研究表明，MANF 缺乏激活了 ATF4/CHOP 和 JNK/c-JUN/CHOP 途径，而 rhMANF 抑制了 MANF 缺失引起的两条促凋亡途径的激活。
综上所述，我们的研究揭示了 MANF、UPR 和肝 I/R 损伤之间以前未知的关系。
