N6-Methyladenosine Demethylase FTO Protects Pancreatic ΒTC6 Cells From Cholesterol-Triggered Damage by Regulating Nfatc4: Insights From RNA-Seq Analysis.

Excessive cholesterol contributes to pancreatic β-cell dysfunction and plays a critical role in the pathogenesis of metabolic disorders. FTO is a well-characterized N6-methyladenosine (m6A) demethylase involved in the regulation of RNA metabolism; however, its role in pancreatic β-cells under cholesterol-induced stress remains poorly understood. The effects of cholesterol on cell viability, apoptosis, pyroptosis, and FTO expression were examined in murine pancreatic BTC6 cells. The functional significance of the FTO-NFATC4 axis was investigated through Fto and Nfatc4 overexpression. RNA sequencing, mRNA stability assays, luciferase reporter assays, and subcellular fractionation analyses were performed to elucidate the underlying regulatory mechanisms. Cholesterol treatment significantly reduced cell viability and promoted apoptosis and pyroptosis in BTC6 cells, accompanied by marked downregulation of FTO expression. RNA-seq analysis identified Nfatc4 as a downstream target of FTO. Mechanistically, Fto overexpression accelerated Nfatc4 mRNA degradation and directly regulated the Nfatc4 3'-UTR, resulting in decreased Nfatc4 expression. Furthermore, Fto overexpression reduced the nuclear accumulation of NFATC4 in cholesterol-treated BTC6 cells. Functionally, forced Nfatc4 expression largely reversed the protective effects of FTO, leading to increased apoptosis and pyroptosis as well as reduced cell viability. FTO protects BTC6 cells against cholesterol-induced injury by suppressing Nfatc4 expression and limiting NFATC4 nuclear accumulation. These findings identify a novel FTO-NFATC4 regulatory axis in pancreatic β-cells and provide new insights into the molecular mechanisms underlying cholesterol-induced β-cell dysfunction, highlighting this pathway as a promising molecular target for the intervention of lipotoxic-mediated pancreatic islet injury.