Abstract：
Dysregulated mitochondrial metabolism occurs in several pathological processes characterized by cell proliferation and migration. Nonetheless, the role of mitochondrial fission is not well appreciated in cardiac fibrosis, which is accompanied by enhanced fibroblast proliferation and migration. We investigated the causes and consequences of mitochondrial fission in cardiac fibrosis using cultured cells, animal models, and clinical samples. Increased METTL3 expression caused excessive mitochondrial fission, resulting in the proliferation and migration of cardiac fibroblasts that lead to cardiac fibrosis. Knockdown of METTL3 suppressed mitochondrial fission, inhibiting fibroblast proliferation and migration for ameliorating cardiac fibrosis. Elevated METTL3 and N6-methyladenosine (m6A) levels were associated with low expression of long non-coding RNA GAS5. Mechanistically, METTL3-mediated m6A methylation of GAS5 induced its degradation, dependent of YTHDF2. GAS5 could interact with mitochondrial fission marker Drp1 directly; overexpression of GAS5 suppressed Drp1-mediated mitochondrial fission, inhibiting cardiac fibroblast proliferation and migration. Knockdown of GAS5 produced the opposite effect. Clinically, increased METTL3 and YTHDF2 levels corresponded with decreased GAS5 expression, increased m6A mRNA content and mitochondrial fission, and increased cardiac fibrosis in human heart tissue with atrial fibrillation. We describe a novel mechanism wherein METTL3 boosts mitochondrial fission, cardiac fibroblast proliferation, and fibroblast migration: METTL3 catalyzes m6A methylation of GAS5 methylation in a YTHDF2-dependent manner. Our findings provide insight into the development of preventative measures for cardiac fibrosis.
摘要：
线粒体代谢失调发生在以细胞增殖和迁移为特征的几种病理过程中。尽管如此，线粒体裂变在心脏纤维化中的作用没有得到很好的重视，伴随着成纤维细胞增殖和迁移的增强。我们使用培养的细胞研究了心肌纤维化中线粒体裂变的原因和后果，动物模型,和临床样本。METTL3表达增加导致线粒体过度分裂，导致心脏成纤维细胞的增殖和迁移，从而导致心脏纤维化。METTL3的敲减抑制了线粒体裂变，抑制成纤维细胞增殖和迁移以改善心脏纤维化。升高的METTL3和N6-甲基腺苷（m6A）水平与长链非编码RNAGAS5的低表达相关。机械上,METTL3介导的GAS5的m6A甲基化诱导其降解，依赖于YTHDF2。GAS5可以直接与线粒体裂变标记物Drp1相互作用；GAS5的过表达抑制了Drp1介导的线粒体裂变，抑制心脏成纤维细胞增殖和迁移。击倒GAS5产生相反的效果。临床上,METTL3和YTHDF2水平升高与GAS5表达降低相对应，m6AmRNA含量增加和线粒体裂变，和增加心脏纤维化的人心脏组织与心房颤动。我们描述了一种新机制，其中METTL3促进线粒体裂变，心脏成纤维细胞增殖，和成纤维细胞迁移：METTL3以YTHDF2依赖性方式催化GAS5甲基化的m6A甲基化。我们的发现为心脏纤维化预防措施的发展提供了见解。
