C-terminal FGF-23 production coupling with aldosterone via FAM20C and predicting cardiovascular events in primary aldosteronism

This study examined the involvement of fibroblast growth factor-23 (FGF-23) in primary aldosteronism (PA), a condition characterized by elevated aldosterone levels and hypertension. We recruited patients with unilateral PA (uPA) and observed increased levels of C-terminal FGF-23 (cFGF-23) and C-terminal to intact FGF-23 (iFGF-23) in patients with uPA compared with essential hypertension control participants. Elevated preoperative cFGF-23 levels were associated with adverse outcomes, including mortality and cardiovascular or kidney events. Plasma cFGF-23 levels demonstrated a nonlinear rise with aldosterone, but iFGF-23 levels were not correlated with plasma aldosterone concentration. Higher cFGF-23 levels independently predicted hypertension remission after adrenalectomy for patients with uPA. Patients with uPA, who exhibited elevated cFGF-23 levels, had decreased levels after adrenalectomy. In cell cultures, aldosterone enhanced cleavage of iFGF-23, leading to increased levels of cFGF-23 fragments, an effect mitigated by silencing of family with sequence similarity 20, member C (FAM20C). However, the enhancement of cFGF-23 levels remained unaffected by the furin inhibitor. The study suggests that aldosterone influences FGF-23 phosphorylation by interacting with FAM20C, with docking experiments indicating aldosterone's binding to FAM20C. This work highlights that patients with uPA with elevated cFGF-23 levels are associated with cardiovascular risks, and adrenalectomy reduces cFGF-23. Aldosterone likely promotes cFGF-23 production through FAM20C-mediated phosphorylation of iFGF-23.