Background:Cardiac fibrosis is a common pathological feature associated with adverse clinical outcome in postinjury remodeling and has no effective therapy. Using an unbiased transcriptome analysis, we identified FMO2 (flavin-containing monooxygenase 2) as a top-ranked gene dynamically expressed following myocardial infarction (MI) in hearts across different species including rodents, nonhuman primates, and human. However, the functional role of FMO2 in cardiac remodeling is largely unknown.Methods:Single-nuclei transcriptome analysis was performed to identify FMO2 after MI; FMO2 ablation rats were generated both in genetic level using the CRISPR-cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat–associated 9) technology and lentivirus-mediated manner. Gain-of-function experiments were conducted using postn-promoter FMO2, miR1a/miR133a-FMO2 lentivirus, and enzymatic activity mutant FMO2 lentivirus after MI.Results:A significant downregulation of FMO2 was consistently observed in hearts after MI in rodents, nonhuman primates, and patients. Single-nuclei transcriptome analysis showed cardiac expression of FMO2 was enriched in fibroblasts rather than myocytes. Elevated spontaneous tissue fibrosis was observed in the FMO2-null animals without external stress. In contrast, fibroblast-specific expression of FMO2 markedly reduced cardiac fibrosis following MI in rodents and nonhuman primates associated with diminished SMAD2/3 (small mothers against decapentaplegic 2/3) phosphorylation. Unexpectedly, the FMO2-mediated regulation in fibrosis and SMAD2/3 signaling was independent of its enzymatic activity. Rather, FMO2 was detected to interact with CYP2J3 (cytochrome p450 superfamily 2J3). Binding of FMO2 to CYP2J3 disrupted CYP2J3 interaction with SMURF2 (SMAD-specific E3 ubiquitin ligase 2) in cytosol, leading to increased cytoplasm to nuclear translocation of SMURF2 and consequent inhibition of SMAD2/3 signaling.Conclusions:Loss of FMO2 is a conserved molecular signature in postinjury hearts. FMO2 possesses a previously uncharacterized enzyme-independent antifibrosis activity via the CYP2J3-SMURF2 axis. Restoring FMO2 expression exerts potent ameliorative effect against fibrotic remodeling in postinjury hearts from rodents to nonhuman primates. Therefore, FMO2 is a potential therapeutic target for treating cardiac fibrosis following injury.

中文翻译：

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FMO2（含单加氧酶 2 的黄素）通过 CYP2J3-SMURF2 轴预防心脏纤维化


背景：心脏纤维化是损伤后重塑中与不良临床结果相关的常见病理特征，并且没有有效的治疗方法。通过无偏转录组分析，我们确定 FMO2（含黄素单加氧酶 2）是不同物种（包括啮齿类动物、非人灵长类动物和人类）心脏中心肌梗死 (MI) 后动态表达的顶级基因。然而，FMO2在心脏重构中的功能作用尚不清楚。方法：通过单核转录组分析来鉴定MI后的FMO2；使用CRISPR-cas9（成簇规则间隔短回文重复序列/成簇规则间隔短回文重复关联9）技术和慢病毒介导的方式在基因水平上产生FMO2消融大鼠。使用 MI后启动子后 FMO2、miR1a/miR133a-FMO2 慢病毒和酶活性突变型 FMO2 慢病毒进行功能获得实验。结果：在啮齿动物、非人灵长类动物、和病人。单核转录组分析显示 FMO2 的心脏表达在成纤维细胞而不是心肌细胞中富集。在没有外部应激的 FMO2 缺失动物中观察到自发组织纤维化升高。相比之下，FMO2 的成纤维细胞特异性表达显着减少了啮齿类动物和非人灵长类动物 MI 后的心脏纤维化，这与 SMAD2/3（小母体对抗十五肢瘫痪 2/3）磷酸化的减弱有关。出乎意料的是，FMO2 介导的纤维化和 SMAD2/3 信号传导调节与其酶活性无关。相反，FMO2 被发现与 CYP2J3（细胞色素 p450 超家族 2J3）相互作用。 FMO2 与 CYP2J3 的结合破坏了 CYP2J3 与胞浆中 SMURF2（SMAD 特异性 E3 泛素连接酶 2）的相互作用，导致 SMURF2 细胞质向核易位增加，从而抑制 SMAD2/3 信号传导。结论：FMO2 的丢失是一个保守的分子特征在受伤后的心脏中。 FMO2 通过 CYP2J3-SMURF2 轴具有先前未表征的酶独立抗纤维化活性。恢复 FMO2 表达对从啮齿动物到非人灵长类动物的损伤后心脏纤维化重塑具有有效的改善作用。因此，FMO2是治疗损伤后心脏纤维化的潜在治疗靶点。