BACKGROUND Long noncoding RNA (lncRNA) can regulate various physiological and pathological processes through multiple molecular mechanisms in cis and in trans. However, the role of lncRNAs in cardiac hypertrophy is yet to be fully elucidated. METHODS A mouse lncRNA microarray was used to identify differentially expressed lncRNAs in the mouse hearts following transverse aortic constriction-induced pressure overload comparing to the sham-operated samples. The direct impact of one lncRNA, Ahit, on cardiomyocyte hypertrophy was characterized in neonatal rat cardiomyocytes in response to phenylephrine by targeted knockdown and overexpression. The in vivo function of Ahit was analyzed in mouse hearts by using cardiac-specific adeno-associated virus, serotype 9-short hairpin RNA to knockdown Ahit in combination with transverse aortic constriction. Using catRAPID program, an interaction between Ahit and SUZ12 (suppressor of zeste 12 protein homolog) was predicted and validated by RNA immunoprecipitation and immunoblotting following RNA pull-down. Chromatin immunoprecipitation was performed to determine SUZ12 or H3K27me3 occupancy on the MEF2A (myocyte enhancer factor 2A) promoter. Finally, the expression of human Ahit (leukemia-associated noncoding IGF1R activator RNA 1 [LUNAR1]) in the serum samples from patients of hypertrophic cardiomyopathy was tested by quantitative real-time polymerase chain reaction. RESULTS A previously unannotated lncRNA, antihypertrophic interrelated transcript (Ahit), was identified to be upregulated in the mouse hearts after transverse aortic constriction. Inhibition of Ahit induced cardiac hypertrophy, both in vitro and in vivo, associated with increased expression of MEF2A, a critical transcriptional factor involved in cardiac hypertrophy. In contrast, overexpression of Ahit significantly attenuated stress-induced cardiac hypertrophy in vitro. Furthermore, Ahit was significantly upregulated in serum samples of patients diagnosed with hypertensive heart disease versus nonhypertrophic hearts (1.46±0.17 fold, P=0.0325). Mechanistically, Ahit directly bound and recruited SUZ12, a core PRC2 (polycomb repressive complex 2) protein, to the promoter of MEF2A, triggering its trimethylation on H3 lysine 27 (H3K27me3) residues and mediating the downregulation of MEF2A, thereby preventing cardiac hypertrophy. CONCLUSIONS Ahit is a lncRNA with a significant role in cardiac hypertrophy regulation through epigenomic modulation. Ahit is a potential therapeutic target of cardiac hypertrophy.

中文翻译：

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长链非编码 RNA Ahit 通过 SUZ12（Zeste 12 蛋白同源物抑制剂）介导的 MEF2A（肌细胞增强因子 2A）下调来防止心脏肥大。

背景长链非编码RNA（lncRNA）可以通过顺式和反式的多种分子机制调控各种生理和病理过程。然而，lncRNAs 在心肌肥厚中的作用尚未完全阐明。方法 与假手术样本相比，小鼠 lncRNA 微阵列用于鉴定横向主动脉收缩引起的压力超负荷后小鼠心脏中差异表达的 lncRNA。一种 lncRNA Ahit 对心肌细胞肥大的直接影响在新生大鼠心肌细胞中通过靶向敲低和过表达对去氧肾上腺素作出反应。通过使用心脏特异性腺相关病毒、血清型 9-短发夹 RNA 结合横向主动脉收缩来击倒 Ahit，在小鼠心脏中分析了 Ahit 的体内功能。使用 catRAPID 程序，Ahit 和 SUZ12（zeste 12 蛋白同源物的抑制子）之间的相互作用通过 RNA 免疫沉淀和 RNA 下拉后的免疫印迹进行预测和验证。进行染色质免疫沉淀以确定 SUZ12 或 H3K27me3 在 MEF2A（肌细胞增强因子 2A）启动子上的占有率。最后，通过定量实时聚合酶链反应检测肥厚型心肌病患者血清样本中人类 Ahit（白血病相关非编码 IGF1R 激活剂 RNA 1 [LUNAR1]）的表达。结果 一种先前未注释的 lncRNA，即抗肥大相关转录物 (Ahit)，经鉴定在横向主动脉收缩后在小鼠心脏中上调。在体外和体内抑制 Ahit 诱导的心脏肥大，与 MEF2A 表达增加有关，MEF2A 是一种参与心脏肥大的关键转录因子。相比之下，Ahit 的过表达显着减弱了体外应激诱导的心脏肥大。此外，与非肥大心脏相比，Ahit 在诊断患有高血压心脏病的患者的血清样本中显着上调（1.46±0.17 倍，P=0.0325）。从机制上讲，Ahit 将核心PRC2（多梳抑制复合物2）蛋白SUZ12 直接结合并招募到MEF2A 的启动子上，触发H3 赖氨酸27（H3K27me3）残基的三甲基化并介导MEF2A 的下调，从而防止心脏肥大。结论 Ahit 是一种 lncRNA，通过表观基因组调节在心脏肥大调节中具有重要作用。