Downregulation of hepatic METTL3 contributes to APAP-induced liver injury in mice.
Downregulation of hepatic METTL3 contributes to APAP-induced liver injury in mice.
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肝METTL3的下调导致小鼠APAP诱导的肝损伤。
DOI：
10.1016/j.jhepr.2023.100766
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发表时间：
2023-08
期刊：
影响因子：
--
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Liu C;Li X;Gao M;Dong Y;Chen Z
对乙酰氨基酚（APAP）过量是西方世界急性肝功能衰竭的主要原因，但其分子机制尚未完全了解。甲基转移酶样3（Methyltransferase-like 3，简称MTL 3）是一种核心的N6-甲基腺苷（m6 A）RNA甲基转移酶，参与多种生理和病理过程的调控。本研究旨在探讨胃L3在APAP诱导的小鼠肝损伤中的作用。使用肝细胞特异性Mettl 3敲除（Mettl 3-HKO）小鼠和腺病毒介导的基因过表达或敲减。我们通过测定血清丙氨酸氨基转移酶/天冬氨酸氨基转移酶活性、坏死面积、细胞死亡、活性氧水平和信号通路的激活来分析APAP诱导的肝损伤。我们还使用各种测定和分子技术进行了机理研究。肝胃L3在APAP诱导的肝损伤中下调，并且肝细胞特异性Mettl 3缺失加速APAP诱导的肝损伤，由于促分裂原活化蛋白激酶激酶4（MKK 4）/ c-Jun NH 2-末端激酶（JNK）信号传导途径的显著活化而导致死亡率增加。SP 600125对JNK的抑制在很大程度上阻断了Mettl 3-HKO小鼠中APAP诱导的肝损伤。Mettl 3的肝缺失通过增加MKK 4和JNK 1/2的蛋白稳定性而激活MKK 4/JNK信号传导途径，这是蛋白酶体活性降低的结果。通过蛋白酶体20 S亚基β 4（PSMB 4）或蛋白酶体20 S亚基β 6（PSMB 6）的过表达恢复蛋白酶体活性导致Mettl 3-HKO肝细胞中MKK 4和JNK的下调。在机制上，胃L3与RNA聚合酶II和活性组蛋白修饰（如H3 K9 ac、H3 K27 ac和H3 K36 me 3）相互作用，以维持蛋白酶体相关基因的表达。我们的研究表明，胃L3的下调通过降低蛋白酶体活性从而增强MKK 4/JNK信号通路的活性来促进APAP诱导的肝损伤。对乙酰氨基酚（APAP）过量是西方世界急性肝功能衰竭的关键原因，但其分子机制尚未完全了解。在这项研究中，我们证明了甲基转移酶样3（methyltransferase-like 3，缩写为L3），一种核心m6 A RNA甲基转移酶，在APAP诱导的肝损伤中下调，这通过增强MKK 4/JNK信号通路并参与蛋白酶体活性降低而加剧APAP诱导的肝损伤。APAP诱导的肝损伤中肝脏β-L3下调。肝细胞特异性Mettl 3缺失加重APAP诱导的肝损伤SP 600125抑制JNK阻断Mettl 3-HKO小鼠中APAP诱导的肝损伤。Mettl 3-HKO通过降低蛋白酶体活性激活MKK 4/JNK信号传导途径。胃L3与Pol II和H3 K9 ac/H3 K27 ac/H3 K36 me 3相互作用以维持蛋白酶体。
Acetaminophen (APAP) overdose is a major cause of acute liver failure in the Western world, but its molecular mechanisms are not fully understood. Methyltransferase-like 3 (METTL3) is a core N6-methyl-adenosine (m6A) RNA methyltransferase that has been shown to regulate many physiological and pathological processes. This study aimed to investigate the role of METTL3 in APAP-induced liver injury in mice. Hepatocyte-specific Mettl3 knockout (Mettl3-HKO) mice and adenovirus-mediated gene overexpression or knockdown were used. We assayed APAP-induced liver injury by measuring serum alanine aminotransferase/aspartate aminotransferase activity, necrotic area, cell death, reactive oxygen species levels and activation of signalling pathways. We also performed mechanistic studies using a variety of assays and molecular techniques. Hepatic METTL3 is downregulated in APAP-induced liver injury, and hepatocyte-specific deletion of Mettl3 accelerates APAP-induced liver injury, leading to increased mortality as a result of the dramatic activation of the mitogen-activated protein kinase kinase 4 (MKK4) / c-Jun NH2-terminal kinase (JNK) signalling pathway. Inhibition of JNK by SP600125 largely blocks APAP-induced liver injury in Mettl3-HKO mice. Hepatic deletion of Mettl3 activates the MKK4/JNK signalling pathway by increasing the protein stability of MKK4 and JNK1/2 as a result of decreased proteasome activity. Restoration of proteasome activity by overexpression of proteasome 20S subunit beta 4 (PSMB4) or proteasome 20S subunit beta 6 (PSMB6) leads to the downregulation of MKK4 and JNK in Mettl3-HKO hepatocytes. Mechanistically, METTL3 interacts with RNA polymerase II and active histone modifications such as H3K9ac, H3K27ac, and H3K36me3 to maintain the expression of proteasome-related genes. Our study demonstrated that downregulation of METTL3 promotes APAP-induced liver injury by decreasing proteasome activity and thereby enhancing activity of the MKK4/JNK signalling pathway. Acetaminophen (APAP) overdose is a key cause of acute liver failure in the Western world, but its molecular mechanisms are not fully understood. We demonstrated in this study that methyltransferase-like 3 (METTL3), a core m6A RNA methyltransferase, is downregulated in APAP-induced liver injury, which exacerbates APAP-induced liver injury through enhancing the MKK4/JNK signalling pathway with involvement of the decreased proteasome activity. Hepatic METTL3 is downregulated in APAP-induced liver injury. Hepatocyte-specific deletion of Mettl3 exacerbates APAP-induced liver injury. Inhibition of JNK by SP600125 blocks APAP-induced liver injury in Mettl3-HKO mice. Mettl3-HKO activates the MKK4/JNK signalling pathway by decreasing proteasome activity. METTL3 interacts with Pol II and H3K9ac/H3K27ac/H3K36me3 to maintain proteasome.
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