Reply to: "The autophagic response to alcohol toxicity: the missing layer"

SREBP1c mediates the effect of acetaldehyde on Cidea expression in Alcoholic fatty liver Mice

Cell death inducing DNA fragmentation factor-alpha-like A (Cidea) is a member of cell death-inducing DFF45-like effector (CIDE) protein. The initial function of CIDE is the promotion of cell death and DNA fragmentation in mammalian cells. Cidea was recently reported to play critical roles in the development of hepatic steatosis. The purpose of present study is to determine the effect of chronic alcohol intake on Cidea expression in the livers of mice with alcoholic fatty liver disease. Cidea expression was significantly increased in the liver of alcohol-induced fatty liver mice. While, knockdown of Cidea caused lipid droplets numbers reduction. Next, we detected the activity of ALDH2 reduction and the concentration of serum acetaldehyde accumulation in our alcohol-induced fatty liver mice. Cidea expression was elevated in AML12 cells exposed to 100uM acetaldehyde. Interestingly, Dual-luciferase reporter gene assay showed that 100 uM acetaldehyde led to the activation of Cidea reporter gene plasmid which containing SRE element. What’s more, the knockdown of SREBP1c suppressed acetaldehyde-induced Cidea expression. Overall, our findings suggest that Cidea is highly associated with alcoholic fatty liver disease and Cidea expression is specifically induced by acetaldehyde, and this up-regulation is most likely mediated by SREBP1c.

Valproic acid attenuates renal fibrosis through the induction of autophagy

BACKGROUND

Renal fibrosis is a common pathological feature of the progression of chronic kidney disease. Although valproic acid (VPA) has been recently shown to induce autophagy, the effect of VPA-induced autophagy on renal fibrosis remains unknown. We, therefore, investigated whether VPA-induced autophagy suppresses renal fibrosis in a mouse model of unilateral ureteral obstruction (UUO).

METHODS

Male C57BL/6 mice were divided into five groups (n = 8 per group): (1) sham group; (2) vehicle group; (3) VPA-treated group; (4) 3-methyladenine (3-MA; autophagy inhibitor)-treated group; and (5) VPA plus 3-MA-treated group. Mice underwent UUO and the kidneys were studied after 5 days. We also investigated the effect of VPA-induced autophagy on α-smooth muscle actin (α-SMA) in transforming growth factor (TGF)-β1-stimulated rat kidney fibroblasts and epithelial cells.

RESULTS

VPA attenuated renal fibrosis and induced autophagy in UUO mice, while 3-MA increased renal fibrosis and suppressed autophagy. In addition, the anti-fibrotic effect of VPA was diminished by 3-MA in UUO mice. In rat kidney fibroblasts and epithelial cells, VPA suppressed TGF-β1-stimulated α-SMA expression and induced autophagy. In contrast, 3-MA enhanced α-SMA expression while inhibiting autophagy. Furthermore, the combined use of VPA and 3-MA treatments increased the expression of α-SMA compared with VPA treatment alone in TGF-β1-stimulated rat kidney fibroblasts and epithelial cells, which was accompanied by the inhibition of autophagy.

CONCLUSION

These findings suggest that VPA may be a candidate drug for the treatment of renal fibrosis through the induction of autophagy.