The Role of Adenine Nucleotide Translocase in the Assembly of Respiratory Supercomplexes in Cardiac Cells

Individual electron transport chain complexes have been shown to assemble into the supramolecular structures known as the respiratory chain supercomplexes (RCS). Several studies reported an associative link between RCS disintegration and human diseases, although the physiological role, structural integrity, and mechanisms of RCS formation remain unknown. Our previous studies suggested that the adenine nucleotide translocase (ANT), the most abundant protein of the inner mitochondrial membrane, can be involved in RCS assembly. In this study, we sought to elucidate whether knockdown (KD) affects RCS formation in H9c2 cardiomyoblasts. Results showed that genetic silencing of ANT1, the main ANT isoform in cardiac cells, stimulated proliferation of H9c2 cardiomyoblasts with no effect on cell viability. KD reduced the ΔΨ but increased total cellular ATP levels and stimulated the production of total, but not mitochondrial, reactive oxygen species. Importantly, downregulation of had no significant effects on the enzymatic activity of individual ETC complexes I-IV; however, RCS disintegration was stimulated in KD cells as evidenced by reduced levels of respirasome, the main RCS. The effects of KD to induce RCS disassembly was not associated with acetylation of the exchanger. In conclusion, our study demonstrates that ANT is involved in RCS assembly.