A novel small molecule inhibitor of p38⍺ MAP kinase augments cardiomyocyte cell cycle entry in response to direct cell cycle stimulation

Background and Purpose Myocardial infarction (MI) is the leading cause of mortality globally due in part to the limited ability of cardiomyocytes (CMs) to regenerate. Recently, we demonstrated that overexpression of four‐cell cycle factors, CDK1, CDK4, cyclin B1 and cyclin D1 (4F), induced cell division in ~20% of the post‐mitotic CMs overexpressed 4F. The current study aims to identify a small molecule that augments 4F‐induced CM cycle induction. Experimental Approach, Key Results Screening of small molecules with a potential to augment 4F‐induced cell‐cycle induction in 60‐day‐old mature human induced pluripotent cardiomyocytes (hiPS‐CMs) revealed N‐(4,6‐Dimethylpyridin‐2‐yl)‐4‐(pyridine‐4‐yl)piperazine‐1‐carbothioamide (NDPPC), which activates cell cycle progression in 4F‐transduced hiPS‐CMs. Autodock tool and Autodock vina computational methods showed that NDPPC has a potential interaction with the binding site at the human p38⍺ mitogen‐activated protein kinase (p38⍺ MAP kinase), a critical negative regulator of the mammalian cell cycle. A p38 MAP kinase activity assay showed that NDPPC inhibits p38⍺ with 5–10 times lower IC50 compared to the other P38 isoforms in a dose‐dependent manner. Overexpression of p38⍺ MAP kinase in CMs inhibited 4F cell cycle induction, and treatment with NDPPC reversed the cell cycle inhibitory effect. Conclusion and Implications NDPPC is a novel inhibitor for p38 MAP kinase and is a promising drug to augment CM cell cycle response to the 4F. NDPPC could become an adjunct treatment with other cell cycle activators for heart failure treatment.