*Article* **Epigenetic Regulation of Alternative mRNA Splicing in Dilated Cardiomyopathy**

**Weng-Tein Gi 1,2,3, Jan Haas 1,2,3, Farbod Sedaghat-Hamedani 1,2,3, Elham Kayvanpour 1,2,3, Rewati Tappu 1,2,3, David Hermann Lehmann 1,3, Omid Shirvani Samani 1,2,3, Michael Wisdom 1,2,3, Andreas Keller 4, Hugo A. Katus 1,2,3 and Benjamin Meder 1,2,3,5,\***


Received: 10 March 2020; Accepted: 12 May 2020; Published: 16 May 2020

**Abstract:** In recent years, the genetic architecture of dilated cardiomyopathy (DCM) has been more thoroughly elucidated. However, there is still insufficient knowledge on the modifiers and regulatory principles that lead to the failure of myocardial function. The current study investigates the association of epigenome-wide DNA methylation and alternative splicing, both of which are important regulatory principles in DCM. We analyzed screening and replication cohorts of cases and controls and identified distinct transcriptomic patterns in the myocardium that differ significantly, and we identified a strong association of intronic DNA methylation and flanking exons usage (*<sup>p</sup>* <sup>&</sup>lt; <sup>2</sup> <sup>×</sup> <sup>10</sup><sup>−</sup>16). By combining differential exon usage (DEU) and differential methylation regions (DMR), we found a significant change of regulation in important sarcomeric and other DCM-associated pathways. Interestingly, inverse regulation of Titin antisense non-coding RNA transcript splicing and DNA methylation of a locus reciprocal to *TTN* substantiate these findings and indicate an additional role for non-protein-coding transcripts. In summary, this study highlights for the first time the close interrelationship between genetic imprinting by DNA methylation and the transport of this epigenetic information towards the dynamic mRNA splicing landscape. This expands our knowledge of the genome–environment interaction in DCM besides simple gene expression regulation.

**Keywords:** dilated cardiomyopathy; DNA methylation; alternative splicing; epigenetics
