α-Ketoglutarate Promotes Cardiomyocyte Proliferation and Heart Regeneration after Myocardial Infarction

The neonatal mammalian heart is capable of substantial regeneration following injury through cardiomyocyte proliferation. However, this regenerative capacity is lost by postnatal (P) day 7. How to stimulate the adult cardiomyocyte to re-enter the cell cycle is still unknown. Accumulating evidence suggests that cardiomyocyte proliferation depends on its metabolic state. Due to the tight connection between the tricarboxylic acid cycle (TCA) and cell proliferation, we analyzed the TCA metabolites between P0.5 and P7 mouse hearts and found that α-ketoglutarate (α-KG) ranked first among the decreased metabolites. The intraperitoneal injection of exogenous α-KG extended the window of cardiomyocyte proliferation during heart development and promoted heart regeneration after myocardial infarction (MI) by inducing adult cardiomyocyte proliferation. This was confirmed in Ogdh-siRNA-treated mice with increased α-KG levels. Mechanistically, α-KG activates Jmjd3, a histone lysine demethylase, that decreases H3K27me3 expression and deposition of H3K4me3 at the promoters of cell cycle and structural maturation genes in cardiomyocytes. Our present study shows that α-KG promotes cardiomyocyte proliferation by Jmjd3-dependent demethylation and inactivation of H3K27me3 andH3K4me3, which is a potential therapeutic approach for treating MI and heart failure. To gain insights into the potential pathways by which α-KG induced cardiomyocyte proliferation, we isolated cardiomyocytes from P21 mice that were daily injected with α-KG or PBS (Control) for 2 weeks and performed gene expression profiling analysis using data obtained from RNA-seq.