Cardiomyocyte-specific Loss of Glutamyl-prolyl-tRNA Synthetase Leads to Disturbed Protein Homeostasis and Dilated Cardiomyopathy

Abstract

AbstractGlutamyl-prolyl-tRNA synthetase (EPRS1), an aminoacyl-tRNA synthetase (ARS) ligating glutamic acid and proline to their corresponding tRNAs, plays an essential role in decoding proline codons during translation elongation. The physiological function of EPRS1 in cardiomyocytes (CMs) and the potential effects of CM-specific loss of EPRS1 remain unknown. Here, we found that heterozygousEprs1knockout in CMs does not cause any significant changes in CM hypertrophy induced by pressure overload, while homozygous knockout leads to dilated cardiomyopathy, heart failure, and lethality at around 1 month afterEprs1deletion. Transcriptomic profiling of early-stageEprs1knockout hearts suggests a significantly decreased expression of multiple ion channel genes and an increased gene expression in proapoptotic pathways and integrated stress response. Proteomic analysis shows decreased protein expression of multi-aminoacyl-tRNA synthetase complex components, fatty acid, and branched-chain amino acid metabolic enzymes, as well as a compensatory increase in cytosolic translation machine-related proteins. Immunoblot analysis indicated that multiple proline-rich proteins were reduced at the early stage, which might contribute to cardiac dysfunction ofEprs1knockout mice. Taken together, this study demonstrates the physiological and molecular outcome of loss-of-function of EPRS1in vivoand provides valuable insights into the potential side effects on CMs resulting from the EPRS1-targeting therapeutic approach.