USP1/UAF1-Stabilized METTL3 Promotes Reactive Astrogliosis and Improves Functional Recovery after Spinal Cord Injury through m6A Modification of YAP1 mRNA
USP1/UAF1-Stabilized METTL3 Promotes Reactive Astrogliosis and Improves Functional Recovery after Spinal Cord Injury through m6A Modification of YAP1 mRNA
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DOI：
10.1523/jneurosci.1209-22.2023
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发表时间：
2023-03-01
影响因子：
5.3
通讯作者：
Cai, Weihua
中科院分区：
文献类型：
--
作者：
Ge, Xuhui;Ye, Wu;Cai, Weihua
RNA N6-甲基腺苷（m6 A）修饰参与多种生物学过程。然而，其在脊髓损伤（SCI）中的作用知之甚少。脊髓损伤后m6 A水平升高，甲基转移酶复合物的核心亚基肌L3在反应性星形胶质细胞中上调，并在SCI后被USP 1/UAF 1复合物进一步稳定。USP 1/UAF 1复合物特异性结合并随后去除K48连接的胃L3蛋白的泛素化，以维持其在SCI后的稳定性。此外，条件性敲除两种性别小鼠的星形胶质细胞瘤L3显著抑制SCI后的反应性星形胶质细胞增生，从而导致炎性细胞的广泛浸润，加重神经元损失，阻碍轴突再生，并损害功能恢复。从机制上讲，YAP 1转录物被鉴定为星形胶质细胞中胃L3的潜在靶点。胃L3可以选择性地甲基化YAP 1转录物的39-UTR区域，其随后以IGF 2BP 2依赖性方式保持其稳定性。在体内，通过腺相关病毒注射的YAP 1过表达显著促进了反应性星形胶质细胞增生，并部分逆转了SCI后胃L3敲除对功能恢复的不利影响。此外，我们发现，胃L3的甲基转移酶活性在反应性星形胶质细胞增生和运动修复中起重要作用，而缺乏甲基转移酶功能的胃L3突变体不能促进SCI后的功能恢复。我们的研究揭示了以前未报道的脊髓损伤中肌L3介导的m6 A修饰的作用，并可能为脊髓损伤提供潜在的治疗方法。
RNA N6-methyladenosine (m6A) modification is involved in diverse biological processes. However, its role in spinal cord injury (SCI) is poorly understood. The m6A level increases in injured spinal cord, and METTL3, which is the core subunit of methyltransferase complex, is upregulated in reactive astrocytes and further stabilized by the USP1/UAF1 complex after SCI. The USP1/UAF1 complex specifically binds to and subsequently removes K48-linked ubiquitination of the METTL3 protein to maintain its stability after SCI. Moreover, conditional knockout of astrocytic METTL3 in both sexes of mice significantly sup-pressed reactive astrogliosis after SCI, thus resulting in widespread infiltration of inflammatory cells, aggravated neuronal loss, hampered axonal regeneration, and impaired functional recovery. Mechanistically, the YAP1 transcript was identified as a potential target of METTL3 in astrocytes. METTL3 could selectively methylate the 39-UTR region of the YAP1 transcript, which subsequently maintains its stability in an IGF2BP2-dependent manner. In vivo, YAP1 overexpression by adeno-associated virus injection remarkably contributed to reactive astrogliosis and partly reversed the detrimental effects of METTL3 knockout on functional recovery after SCI. Furthermore, we found that the methyltransferase activity of METTL3 plays an essen-tial role in reactive astrogliosis and motor repair, whereas METTL3 mutant without methyltransferase function failed to promote functional recovery after SCI. Our study reveals the previously unreported role of METTL3-mediated m6A mod-ification in SCI and might provide a potential therapy for SCI.