Endothelial FUNDC1 regulates metabolic reprogramming and the obesity-diabetes transition through the SIRT3/GATA2/endothelin-1 axis.

Endothelial cell (EC) dysfunction is a hallmark of obesity and Type 2 diabetes mellitus (T2DM), yet the mechanisms linking vascular stress to systemic metabolic diseases remain unclear. Here, we investigated the role of the mitochondrial protein FUN14 domain-containing 1 (FUNDC1) in EC under nutritional overload. Using high-fat diet (HFD)-fed EC-specific Fundc1 knockout mice, human umbilical vein ECs, primary ECs, and vascular tissues from patients with obese/T2DM, we find that endothelial FUNDC1 expression is elevated under diabetic conditions, whereas its deletion protects mice from HFD-induced obesity, insulin resistance, and metabolic disorders. Mechanistically, overnutrition triggers nuclear export of the long isoform of SIRT3 (SIRT3-L) to mitochondria via FUNDC1, disinhibiting GATA2 and enhancing endothelin-1 (ET-1) production. Loss of FUNDC1 in ECs retains SIRT3-L in the nucleus, promoting GATA2 degradation and reducing ET-1. Endothelial FUNDC1 levels correlated positively with plasma ET-1 in individuals with obesity/T2DM. These findings identify endothelial FUNDC1 as a key regulator of vasculature-metabolic organ cross talks and obesity-diabetes transition.