BACKGROUND The tumor suppressor and proapoptotic transcription factor P53 is induced (and activated) in several forms of heart failure, including cardiotoxicity and dilated cardiomyopathy; however, the precise mechanism that coordinates its induction with accessibility to its transcriptional promoter sites remains unresolved, especially in the setting of mature terminally differentiated (nonreplicative) cardiomyocytes. METHODS Male and female control or TRIM35 (tripartite motif containing 35) overexpression adolescent (aged 1-3 months) and adult (aged 4-6 months) transgenic mice were used for all in vivo experiments. Primary adolescent or adult mouse cardiomyocytes were isolated from control or TRIM35 overexpression transgenic mice for all in vitro experiments. Adenovirus or small-interfering RNA was used for all molecular experiments to overexpress or knockdown, respectively, target genes in primary mouse cardiomyocytes. Patient dilated cardiomyopathy or nonfailing left ventricle samples were used for translational and mechanistic insight. Chromatin immunoprecipitation and DNA sequencing or quantitative real-time polymerase chain reaction (qPCR) was used to assess P53 binding to its transcriptional promoter targets, and RNA sequencing was used to identify disease-specific signaling pathways. RESULTS Here, we show that E3-ubiquitin ligase TRIM35 can directly monoubiquitinate lysine-120 (K120) on histone 2B in postnatal mature cardiomyocytes. This epigenetic modification was sufficient to promote chromatin remodeling, accessibility of P53 to its transcriptional promoter targets, and elongation of its transcribed mRNA. We found that increased P53 transcriptional activity (in cardiomyocyte-specific Trim35 overexpression transgenic mice) was sufficient to initiate heart failure and these molecular findings were recapitulated in nonischemic human LV dilated cardiomyopathy samples. CONCLUSIONS These findings suggest that TRIM35 and the K120Ub-histone 2B epigenetic modification are molecular features of cardiomyocytes that can collectively predict dilated cardiomyopathy pathogenesis.

中文翻译：

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TRIM35 单泛素化心肌细胞中的 H2B，对心力衰竭的影响。


背景肿瘤抑制因子和促凋亡转录因子 P53 在多种形式的心力衰竭中被诱导（和激活），包括心脏毒性和扩张型心肌病；然而，协调其诱导与其转录启动子位点的可及性的精确机制仍未解决，特别是在成熟的终末分化（非复制）心肌细胞的情况下。方法所有体内实验均使用雄性和雌性对照或TRIM35（含有35个三部分基序）过度表达的青少年（1-3个月大）和成年（4-6个月大）转基因小鼠。所有体外实验均从对照或 TRIM35 过表达转基因小鼠中分离原代青少年或成年小鼠心肌细胞。所有分子实验均使用腺病毒或小干扰RNA，分别过表达或敲低原代小鼠心肌细胞中的靶基因。使用患者扩张型心肌病或非衰竭左心室样本来了解转化和机制。使用染色质免疫沉淀和 DNA 测序或定量实时聚合酶链反应 (qPCR) 来评估 P53 与其转录启动子靶标的结合，并使用 RNA 测序来识别疾病特异性信号通路。结果在这里，我们发现 E3-泛素连接酶 TRIM35 可以直接单泛素化出生后成熟心肌细胞中组蛋白 2B 上的赖氨酸 120 (K120)。这种表观遗传修饰足以促进染色质重塑、P53 对其转录启动子靶标的可及性以及其转录 mRNA 的延伸。 我们发现，P53 转录活性的增加（在心肌细胞特异性 Trim35 过表达转基因小鼠中）足以引发心力衰竭，并且这些分子发现在非缺血性人类左室扩张型心肌病样本中得到了重现。结论 这些发现表明 TRIM35 和 K120Ub-组蛋白 2B 表观遗传修饰是心肌细胞的分子特征，可以共同预测扩张型心肌病的发病机制。