m6A metabolism in cardiomyozytes

与DNA修饰类似，在过去的几年里，心血管系统中出现了一种mRNA修饰的表位转录组。具体地说，N6-甲基腺苷(M6A)作为mRNAs中可逆转录后修饰的发现，引起了人们对心肌细胞中的这些修饰及其在疾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基因表达调控的相关机制。因此，人类心脏组织和动物模型心脏标本中的m6A-mRNA-甲基组被报道，并指出m6A修饰在心功能和心力衰竭的病理生理学中的重要作用。M6A在不同物种中的存在，编写器、擦除器和读取器的保守，以及与相关调控蛋白耗尽相关的严重表型表明，m6A在心脏生理学和病理生理学中具有基础作用。然而，在心肌细胞中，应激反应中特定转录物甲基化的变化是如何调节的，以及哪些阅读器蛋白参与了m6A对基因表达的转录后控制，这在很大程度上是未知的。我们在高通量筛选中发现，在横动脉缩窄(TAC)诱导的急性压力超负荷后，心肌细胞中腺苷转移酶2α(MAT2A)的表达和活性增加。MAT2A利用蛋氨酸和三磷酸腺苷生成S-腺苷甲硫氨酸。SAM是不同转甲基化反应的甲基的主要供体，也通过RNA甲基转移酶用于RNA甲基化。此外，在衰竭心肌中，m6A阅读器蛋白“含YthH结构域的家族蛋白2”(Ythdf2)的表达增加。Mat2a和Ythdf2在心脏中的功能在很大程度上是未知的。我们的目标是研究M6A甲基化的机制，并利用最先进的方法在体外和体内表征调节M6A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.