In contrast to adult, neonatal cardiomyocytes are able to proliferate and lose this capacity soon after birth when they withdraw from the cell cycle, become binucleated and differentiate. The arrest of cardiomyocytes cell cycle can be reversible for a short period, conferring the neonatal heart a regenerative potential within the first week of postnatal life. In the timeframe surrounding birth, heart maturation is also characterized by a change in energy metabolism, switching from glycolysis to beta-oxidation. However little is known about how metabolic programming in postnatal cardiomyocytes regulates their ability to proliferate, become binucleated and differentiate. In this study, we show that blocking beta-oxidation in mouse neonatal cardiomyocytes with etomoxir treatment promotes glycolysis and cell cycle re-entry, while increasing fatty acid beta-oxidation but reducing glycolysis leads to a decrease of the number of proliferating cardiomyocytes. In neonatal mice our data demonstrate that cardiomyocytes undergo binucleation and differentiation during the first week after birth and this process is correlated with the upregulation of the natriuretic peptides, ANP and BNP expression. Notably, in the postnatal mouse heart, beta-oxidation blockade through in vivo etomoxir injections, increases ventricular cardiomyocytes number, decreases natriuretic peptides expression and reduces the conversion of cardiomyocytes from a mononucleated to a binucleated phenotype. These findings highlight the importance of metabolic programming in regulating cardiomyocyte proliferation and suggest a potential therapeutic target for heart regeneration by modulating energy metabolic programming.
Epigenetics and Fetal Metabolic Programming: A Call for Integrated Research on Larger Cohorts