m6A metabolism in cardiomyozytes

与DNA修饰类似，在过去几年中，在心血管系统中出现了mRNA修饰的表位转录组。具体而言，N6-甲基腺苷（m6 A）作为mRNA中可逆的转录后修饰的发现引起了对心肌细胞中这些修饰及其在患病心脏中的作用的科学兴趣。mRNA修饰已被认为是疾病心肌细胞中基因表达调控的相关机制。因此，报告了人心脏组织和动物模型心脏样品的m6 A-mRNA-甲基化组，并指出了m6 A修饰对心脏功能和心力衰竭病理生理学的重要作用。m6 A在不同物种中的存在、书写者、擦除者和阅读者的保守性以及与相关调节蛋白的耗竭相关的严重表型表明m6 A在心脏生理学和病理生理学中的基本作用。然而，在心肌细胞中，如何调节特定转录物在应激反应中的甲基化变化，以及哪些阅读器蛋白参与m6 A对基因表达的转录后控制，在很大程度上是未知的。我们在高通量筛选中发现，在由横主动脉缩窄（TAC）诱导的急性压力超负荷后，心肌细胞中腺苷转移酶2 α（Mat 2a）的表达和活性增加。Mat 2a使用甲硫氨酸和三磷酸腺苷（ATP）产生S-腺苷甲硫氨酸（SAM）。SAM是不同甲基转移反应的甲基的主要供体，也用于通过RNA甲基转移酶进行RNA甲基化。此外，m6 A阅读器蛋白“含YTH结构域家族蛋白2”（Ythdf 2）的表达在心肌衰竭时增加。Mat 2a和Ythdf 2在心脏中的功能在很大程度上是未知的。我们的目的是研究m6 A甲基化的机制，并使用最先进的方法在体外和体内表征调节m6 A代谢的关键蛋白对心脏功能的影响。

Similar to DNA modifications, an epitranscriptome of mRNA modifications emerged over the last few years in the cardiovascular system. Specifically, the discovery of the N6-methyladenosine (m6A) as reversible posttranscriptional modification in mRNAs raised scientific interest in those modifications in cardiomyocytes and their role in diseased hearts. mRNA modifications have been recognized as a relevant mechanism for the regulation of gene expression in diseased cardiomyocytes. Consequently, m6A-mRNA-methylomes of human cardiac tissue and of animal model heart-samples were reported and shed point towards an important role of m6A modifications on cardiac function and in the pathophysiology of heart failure. The presence of m6A across different species, the conservation of writers, erasers and readers and the severe phenotypes associated with depletion of involved regulatory proteins suggest a fundamental role of m6A in cardiac physiology and pathophysiology. However, how changes in methylation of specific transcripts in response to stress are regulated in cardiomyocytes and which reader proteins are involved in post-transcriptional control of gene expression by m6A is largely unknown. We identified in a high-throughput screen that the expression as well as activity of adenosyltransferase 2 alpha (Mat2a) is increased in cardiomyocytes after acute pressure overload induced by transverse aortic constriction (TAC). Mat2a generates S-adenosylmethionine (SAM) using methionine and Adenosine triphosphate (ATP). SAM is the primary donor of methyl groups to different transmethylation reactions and is also used for RNA methylation via RNA methyltransferases. Moreover, the expression of the m6A reader protein "YTH domain-containing family protein 2" (Ythdf2) is increased failing myocardium. The function of Mat2a as well as Ythdf2 in the heart is largely unknown. We aim to study mechanisms responsible for m6A methylation and characterize the impact of key proteins regulating m6A-metabolism on cardiac function in vitro and in vivo using state of the art methods.