Metabolic and age-associated epigenetic barriers during direct reprogramming of mouse fibroblasts into induced cardiomyocytes

Heart disease is the leading cause of mortality in developed countries novel regenerative procedures are warranted for improving patients well fare. Direct cardiac conversion (DCC) can create induced cardiomyocytes (iCMs) and besides holding great promise, lacks clinical effectiveness for cardiac regeneration as metabolic and age-associated barriers remains elusive. Here, we identify by histone post-translational analysis that DCC triggers major age-dependent alterations in the epigenetic landscape. Metabolomics revealed decrease abundance of anabolic metabolites related to TCA cycle and glutaminolysis and profound mitochondrial network remodeling, with increased elongation and interconnectivity and reliance in mitochondrial respiration in iCMs. Importantly, adult-derived iCMs present increase accumulation of oxidative stress in the mitochondria and pharmacological activation of mitophagy increase DCC of adult fibroblasts in vitro . Metabolic modulation in vitro and dietary manipulations in vivo improves DCC efficiency and are accompanied by significant alterations in the histone acetylation and methylation landscape and mitochondria homeostasis. Our study provides evidence that metaboloepigenetics as a direct role in cell fate transitions driving direct cardiac conversion into iCMs, highlighting the potential use of metabolic modulation in increasing cardiac regenerative strategies. ### Competing Interest Statement The authors have declared no competing interest. LC-MS based metabolomics and histone proteomics data from this work and uncropped immunoblots are available in supplemental information (Table S1-S4 and Supplementary Figure S4 and S7). The LC-MS based histone proteomics data have been deposited in the ProteomeXchange Consortium PRIDE partner repository with the dataset identifier PXD046542. This paper does not report original code. Any additional information required to reanalyze the data reported in this paper is available from the lead contact upon request.