Fig. 7

Ursolic acid (UA) reduces the pathological tau load to improve social memory via TFEB. a Treatment with 30 μmol/L UA markedly reduced the total tau (tau5, HT7) and phosphorylated tau (p-Tau, AT8) levels in primary neurons instantly transferred with hTau, determined by Western blotting. b Treatment with 30 μmol/L UA for 12 h increased the translocation of TFEB from the cytoplasm to the nucleus, as detected by immunostaining. Green: TFEB; blue: DAPI. Scale bar = 25 μm. c UA treatment significantly increased LC3B-II and decreased p62 levels in HEK293-hTau cells, as determined by Western blotting. d Increased colocalization of mRFP and GFP was observed in HEK293-hTau cells transfected with the tandem fluorescent mRFP-GFP-LC3 (tfLC3) construct, indicating that an increased number of autophagosomes did not fuse with the lysosome. The number of red puncta (mature autolysosomes) increased in the UA-treated group, suggesting that UA promoted autophagy. Scale bar = 10 μm. e Timeline of the experimental procedures. f Knocking down TFEB effectively decreased TFEB levels in vCA1-hTau mice. g, h Knocking down TFEB attenuated UA-induced increases in LC3B-II, decreases in p62, total tau (tau5, HT7) and phosphorylated tau (p-Tau, AT8) in vCA1-hTau mice. i Knocking down TFEB had no significant effect on sociability. j Knocking down TFEB effectively attenuated the UA-induced increase in interaction time with novel mice and social discrimination score in vCA1-hTau mice. hTau + shNT + UA (L): n = 9; hTau + shTFEB + UA (L): n = 8. ^*P < 0.05; ^**P < 0.01, as determined by one-way ANOVA, two-way ANOVA or two-tailed unpaired t test. The data are expressed as the mean ± SEM. L low-dose, TFEB transcription factor EB, mRFP mCherry red fluorescence protein, GFP green fluorescence protein, LC3B microtubule-associated proteins 1A/1B light chain 3B, p62 sequestosome-1, i.g. intragastric administration