Circular RNAs are enriched in cardiac tissue and play important roles in the pathogenesis of heart diseases. In this study, we aimed to investigate the regulatory mechanism of a conserved heart-enriched circRNA, circPan3, in cardiac hypertrophy. Cardiac hypertrophy was induced by isoproterenol. The progression of cardiomyocyte hypertrophy was assessed by sarcomere organization staining, cell surface area measurement, and expression levels of cardiac hypertrophy markers. RNA interactions were detected by RNA pull-down assays, and methylated RNA immunoprecipitation was used to detect m6A level. The expression of circPan3 was downregulated in an isoproterenol-induced cardiac hypertrophy model. Forced expression of circPan3 attenuated cardiomyocyte hypertrophy, while inhibition of circPan3 aggravated cardiomyocyte hypertrophy. Mechanistically, circPan3 was an endogenous sponge of miR-320-3p without affecting miR-320-3p levels. It elevated the expression of HSP20 by endogenously interacting with miR-320-3p. In addition, circPan3 was N6-methylated. Stimulation by isoproterenol downregulated the m6A eraser ALKBH5, resulting in N6-methylation and destabilization of circPan3. Our research is the first to report that circPan3 has an antihypertrophic effect in cardiomyocytes and revealed a novel circPan3-modulated signalling pathway involved in cardiac hypertrophy. CircPan3 inhibits cardiac hypertrophy by targeting the miR-320-3p/HSP20 axis and is regulated by ALKBH5-mediated N6-methylation. This pathway could provide potential therapeutic targets for cardiac hypertrophy.

中文翻译：

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环状RNA-circPan3通过miR-320-3p/HSP20轴减轻心脏肥大

环状RNA在心脏组织中富集，在心脏病的发病机制中发挥重要作用。在本研究中，我们旨在研究富含心脏的保守 circRNA circPan3 在心脏肥大中的调节机制。异丙肾上腺素诱导心脏肥大。通过肌节组织染色、细胞表面积测量和心脏肥大标志物的表达水平来评估心肌细胞肥大的进展。通过 RNA Pull-down 测定检测 RNA 相互作用，并使用甲基化 RNA 免疫沉淀法检测 m6A 水平。在异丙肾上腺素诱导的心脏肥大模型中，circPan3 的表达下调。circPan3的强制表达减弱了心肌细胞肥大，而抑制circPan3则加剧了心肌细胞肥大。从机制上讲，circPan3 是 miR-320-3p 的内源性海绵，不影响 miR-320-3p 水平。它通过与 miR-320-3p 内源性相互作用来提高 HSP20 的表达。此外，circPan3 被 N6-甲基化。异丙肾上腺素刺激下调 m6A 擦除器 ALKBH5，导致 N6 甲基化和 circPan3 不稳定。我们的研究首次报道了 circPan3 在心肌细胞中具有抗肥厚作用，并揭示了一种新的 circPan3 调节的参与心脏肥大的信号通路。CircPan3 通过靶向 miR-320-3p/HSP20 轴抑制心脏肥大，并受 ALKBH5 介导的 N6 甲基化调节。该途径可以为心脏肥大提供潜在的治疗靶点。