MiR-455-3p overexpression reversed the increased fat accumulation and upregulation of TCONS_00039830 and Smad2. Altogether, exosomes derived from rats with OSA promoted hepatic steatosis by increasing the activity of the TCONS_00039830/miR-455-3p/Smad2 axis in MASLD. Here, SMAD2 is linked to fatty liver disease.