The pseudoenzyme ADPRHL1 affects cardiac function by regulating the ROCK pathway

Pseudoenzymes, catalytically deficient variants of active enzymes, have a wide range of regulatory functions. ADP-ribosylhydrolase like-1 (ADPRHL1), which belongs to a small group of ADP-ribosylhydrolase enzymes, lacks the amino acid residues required for catalytic activity, and is therefore considered a pseudoenzyme. Here, to investigate the role of ADPRHL1 in the heart, we established, for the first time, an in vitro ADPRHL1 knockout human myocardial cell culture model. These ADPRHL1 knockout cardiomyocytes adhered abnormally. However, the lack of ADPRHL1 disrupted the formation of focal adhesions in these cardiomyocytes by excessively upregulating the ROCK–myosin II pathway. Inhibitors of ROCK and myosin II effectively restored the focal adhesions in these ADPRHL1-deficient cardiomyocytes and improved electrical conduction and calcium activity. Our findings reveal that ADPRHL1 plays a major role in cardiac function by regulating the ROCK pathway, suggesting that it may serve as a potential drug target for the treatment of ADPRHL1-related diseases. Overall design: To elucidate how ADPRHL1 deficiency prevents the formation of FAs, WT-CMs and KO-CMs were collected for global transcriptome analysis within 3 days after re-seeding.