MITOCHONDRIAL METABOLISM AND HYPOXIC SIGNALLING IN DIFFERENTIATED HUMAN CARDIOMYOCYTE AC16 CELL LINE

Cardiovascular diseases are associated with an altered cardiomyocyte metabolism. Due to a shortage of human heart tissue, experimental studies mostly rely on alternative approaches including animal and cell culture models. Since the use of isolated primary cardiomyocytes is limited, immortalized cardiomyocyte cell lines may represent a useful tool as they closely mimic human cardiomyocytes. This study is focused on the AC16 cell line generated from adult human ventricular cardiomyocytes. Despite an increasing number of articles employing AC16 cells, the comprehensive proteomic, bioenergetic and oxygen-sensing characterization of proliferating versus differentiated cells is still lacking. Here, we provide a comparison of these two stages, particularly emphasizing cell metabolism, mitochondrial function, and hypoxic signalling. The label-free quantitative mass spectrometry revealed a decrease in autophagy and cytoplasmic translation in differentiated AC16, confirming their phenotype. Cell differentiation led to the global increase in mitochondrial proteins (e.g. OXPHOS proteins, TFAM, VWA8, etc.) reflected by elevated mitochondrial respiration. Fatty acid oxidation proteins were increased in differentiated cells, while the expression levels of proteins associated with fatty acid synthesis were unchanged, and glycolytic proteins were decreased. There was a profound difference between proliferating and differentiated cells in their response to hypoxia and anoxia/reoxygenation. We conclude that AC16 differentiation leads to proteomic and metabolic shifts and altered cell response to oxygen deprivation. This underscores the requirement for proper selection of particular differentiation state during experimental planning.