Fig 2: TFEB knockdown weakens the effects of liraglutide on lysosome biogenesis and lipid accumulation. (A) Western blot detection of TFEB and its downstream targets CTSB and LAMP1 in HepG2 cells expressing TFEB-siRNA or control-siRNA. Relative expression levels were normalized to ß-actin levels. (B) Lipid droplets in HepG2 cells treated with TFEB-siRNA or control-siRNA were detected via labeling with the lipid dye BODIPY 493/503 (green). Nuclei were stained with DAPI (scale bars = 50 µm). (C) The TG content of HepG2 cells. The data are expressed as the mean ± SEM; n = 3. *P < 0.01, **P < 0.05 and #P < 0.01 vs. siCON + PA group; &P < 0.01 vs. siCON + PA + LG group.

Fig 3: Schematic diagram of the mechanism of liraglutide-mediated alleviation of hepatic steatosis. HFD or PA exposure inhibits TFEB dephosphorylation and nuclear translocation. TFEB regulates lysosomal biogenesis and function. The blocking of TFEB nuclear translocation leads to autophagic flux impairment and subsequently aggravates hepatic steatosis. Liraglutide, a GLP-1R agonist, alleviates hepatic steatosis through enhancing autophagic flux. Mechanistically, liraglutide activates TFEB and its downstream targets through activation of GLP-1R.

Fig 4: Liraglutide stimulates lysosome biogenesis by inducing TFEB nuclear translocation. (A) Expression of nuclear TFEB, CTSB, and LAMP1 in the livers of HFD-fed mice treated with or without liraglutide. Relative expression levels were normalized to ß-actin and Histone 3 levels. (B) HepG2 cells were co-incubated with or without PA and liraglutide for 24 h. After fixation, immunofluorescence staining was performed for TFEB localization (scale bars = 50 µm). (C) Western blot detection of cytoplasm and nuclear TFEB expression in HepG2 cells treated with or without liraglutide. Relative expression levels were normalized to GAPDH and Histone 3 levels, respectively. (D) Western blot detection of CTSB and LAMP1 expression in HepG2 cells. The data are expressed as mean ± SEM; n = 3. *P < 0.01, **P < 0.05 vs. BSA group; #P < 0.01, ##P < 0.05 vs. PA group.