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

#### **Rebecca M. Parodi-Rullán 1,**†**, Xavier Chapa-Dubocq 1, Roberto Guzmán-Hernández 1, Sehwan Jang 1, Carlos A. Torres-Ramos 1, Sylvette Ayala-Peña 2 and Sabzali Javadov 1,\***


Received: 25 June 2019; Accepted: 11 October 2019; Published: 13 October 2019

**Abstract:** 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 *ANT* knockdown (KD) a ffects 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 e ffect on cell viability. *ANT1* KD reduced the ΔΨ m but increased total cellular ATP levels and stimulated the production of total, but not mitochondrial, reactive oxygen species. Importantly, downregulation of *ANT1* had no significant e ffects on the enzymatic activity of individual ETC complexes I–IV; however, RCS disintegration was stimulated in *ANT1* KD cells as evidenced by reduced levels of respirasome, the main RCS. The e ffects of *ANT1* 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.

**Keywords:** H9c2 cardiomyoblasts; mitochondria; adenine nucleotide translocase; respiratory supercomplexes; ETC complexes
