Abstract 119: PRMT5 Is A New Epigenetic Regulator In Cardiovascular Disease

Abstract

Protein arginine methylation is an abundant posttranslational modification involved in various cellular events such as DNA repair, splicing, and transcription. Protein arginine methyltransferases (PRMTs) catalyze the symmetric and asymmetric dimethylation of arginines and can be subdivided into two distinct families: type I enzymes catalyze the formation of asymmetric dimethylation whereas type II enzymes enhance the addition of symmetric methyl groups.

Here, we report evidence that PRMT5 a type II enzyme serves as an important epigenetic regulator in myocardial disease.

We identified PRMT5 via mass spectrometry as an interactant of class IIa histone deacetylases (HDACs). Additional cardiac interaction partners of PRMT5 were identified by a human cDNA library based yeast-two-hybrid screen. Thereby we elucidated Interleukin enhancer binding factor 3 (ILF3) as a putative interacting protein. ILF3 is a member of the NFAT family. NFAT signalling is known to be a potent driver of cardiomyocyte hypertrophy. Accordingly, we detected a 40% decrease in the size of neonatal rat ventricular myocytes in response to siRNA mediated knockdown of prmt5. A dominant-negative version of PRMT5 is capable of interfering with the Calcineurin-NFAT axis and blocks NFAT activation. In vivo knockdown of endogenous prmt5 in the zebrafish led to a distinct cardiac phenotype with altered morphology and impaired function. To further elucidate prmt5 function in vivo we use mice with floxed prmt5 alleles. As a loss of prmt5 is lethal in the ES cell stadium we use an inducible α myosin heavy chain Mer-Cre-Mer system. Knockout mice display a complete loss of PRMT5 in cardiomyocytes. In line with our in vitro studies these mice are viable and show no phenotype under baseline conditions.

Our work in progress investigates the hypothesis that class IIa HDACs serve as a scaffold to recruit PRMT5 to the DNA, forming a complex with ILF3 to block NFAT activity and the pro-hypertrophic gene program.