Comparative Proteomic Analysis Reveals the Up-Regulation of Ketogenesis in Cardiomyocytes Differentiated from Induced Pluripotent Stem Cells.

Diverse metabolic pathways, such as the tricarboxylic acid cycle, pyruvate metabolism, and oxidative phosphorylation, regulate the differentiation of induced pluripotent stem cells (iPSCs) to cells of specific lineages and organs. Here, we characterized the protein dynamics during cardiac differentiation of human iPSCs into cardiomyocytes (CMs). Differentiation was induced by IWP2, a Wnt signaling inhibitor, and confirmed by the mRNA and protein expression of cTnT and MLC2A in CMs. For comparative proteomics, cells from three stages, namely, hiPSCs, cardiac progenitor cells (CPCs), and CMs, were prepared using the three-plex tandem mass tag labeling (TMT) approach. In total, we identified 3,970 proteins in triplicate analysis. As the result, we observed up-regulation of proteins associated with branched chain amino acid (BCAA) degradation and ketogenesis by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The levels of HMGCL, HMGCS2, and BDH1, involved in ketone body metabolism, were determined using western blotting, and the level of acetoacetate, the final product of ketogenesis, was higher in CMs. Taken together, these observations indicate that proteins required for the production of diverse energy sources were naturally self-expressed during cardiomyogenic differentiation. Furthermore, acetoacetate concentration might act as a regulator of this differentiation. This article is protected by copyright. All rights reserved.