Atp5po, encoding the oligomycin sensitivity conferring protein, is a component of the mitochondrial ATPase. Mitochondrial complex V, of which Atp5po is a part, is crucial for oxidative phosphorylation, catalyzing ATP generation. This process is fundamental for cellular energy production, thus making Atp5po important for normal cell function and development. Genetic models like zebrafish are valuable for studying Atp5po [2].

In zebrafish, overexpression of Atp5po led to a significant reduction of enteric nervous system (ENS) cells, and in vitro studies showed decreased ATP5PO protein levels, impaired neuronal differentiation, and reduced mitochondrial ATP production. Epistasis was observed between ATP5PO and ret, the most important Hirschsprung disease (HSCR) gene, suggesting ATP5PO levels are crucial for normal ENS development and may be responsible for the increased HSCR risk in Down Syndrome (DS) patients, especially with RET variants [1].

In humans, a homozygous splice variant in ATP5PO disrupted mitochondrial complex V function, causing Leigh syndrome in affected individuals. Fibroblasts from these patients had decreased ATP5PO protein, defective complex V assembly, and reduced hydrolytic activity [2]. An intronic splice-disrupting alteration in compound heterozygosity with a nonsense variant in ATP5PO was found in a patient with variable neurologic phenotypes, and immunohistochemistry revealed significantly reduced ATPase amounts associated with this ATP5PO mutation [3].

In conclusion, Atp5po is essential for mitochondrial function, specifically in ATP synthesis through oxidative phosphorylation. Model-based research, such as in zebrafish, has revealed its role in ENS development and its association with HSCR in DS patients. In humans, mutations in ATP5PO are linked to Leigh syndrome and variable neurologic phenotypes, highlighting its significance in understanding these disease mechanisms.