MYSM1 Mediates Cardiac Parthanatos and Hypertrophy by Deubiquitinating PARP1

Cardiac hypertrophy constitutes the primary pathological basis for heart failure and exerts a considerable influence on morbidity and mortality. Deubiquitinating enzymes are crucial regulators of protein degradation and play a pivotal role in cardiac pathophysiology. This study aimed to clarify the involvement of a deubiquitinating enzyme, MYSM1 (Myb-like, SWIRM [Swi3p, Rsc8p and Moira], and MPN [Mpr1/Pad1 N-terminal] domains 1), in cardiac hypertrophy and to explore the underlying mechanism.

Cardiac hypertrophy was developed by angiotensin II or transverse aortic constriction surgery. Cardiomyocyte-specific knockdown of MYSM1 was accomplished using the adeno-associated virus serotype 9-cTNT-Mysm1-shRNA. Co-immunoprecipitation combined with liquid chromatography-tandem mass spectrometry analysis was utilized to identify potential substrates of MYSM1.

First, we discovered that the expression of MYSM1 increases during cardiac hypertrophy. MYSM1 knockdown mitigated cardiac dysfunction and hypertrophy after angiotensin II administration. Cardiomyocyte-specific knockdown of MYSM1 with adeno-associated virus serotype 9 alleviated myocardial dysfunction and hypertrophy caused by transverse aortic constriction surgery. Through co-immunoprecipitation and LC-MS, poly (ADP-ribose) polymerase 1 (PARP1) was identified as a potential substrate protein of MYSM1. PARP1 initiates a novel form of programmed cell death termed parthanatos, which is characterized by excessive PARylation, nuclear translocation of AIF, and depletion of nicotinamide adenine dinucleotide. MYSM1 deubiquitinates and stabilizes PARP1 in an MPN domain-dependent manner. In addition, MYSM1 mediates cardiac hypertrophy through PARP1-dependent cardiomyocyte parthanatos.

This study identified the role of the MYSM1-PARP1 axis in mediating cardiac hypertrophy and suggested that MYSM1 is a promising pharmacological target for the treatment of cardiac hypertrophy.