Defects in lipid homeostasis reflect the function of TANGO2 in Acyl-CoA metabolism

We show that TANGO2, which lacks a transmembrane domain localizes predominantly to mitochondria and transiently to endoplasmic reticulum (ER) and lipid droplets (LDs). Evaluation of lipids in HepG2 cells lacking TANGO2 revealed an increase in the size of lipid droplets and reactive oxygen species production. There is also a marked increase lysophosphatidic acid (LPA) and a concomitant decrease in its biosynthetic precursor phosphatidic acid (PA). These changes are exacerbated in nutrient starved cells. Based on our data, we suggest that the principle function of TANGO2 is in acyl-CoA metabolism, which is necessary for the acylation of LPA to generate PA. This defect subsequently affects metabolism of many other fatty acids. These data help explain the physiological consequence of TANGO2 that induce acute metabolic crisis including rhabdomyolysis, cardiomyopathy and cardiac arrhythmias often leading to fatality upon starvation and stress.