Yaran Wu - Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Third Military Medical University, Chongqing ۴۰۰۰۳۸, China
Xufang Dai - Department of Educational Science College, Chongqing Normal University, Chongqing ۴۰۰۰۴۷, China
Zhenhong Ni - Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Third Military Medical University, Chongqing ۴۰۰۰۳۸, China
Xiaojing Yan - Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Third Military Medical University, Chongqing ۴۰۰۰۳۸, China
Fengtian He - Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Third Military Medical University, Chongqing ۴۰۰۰۳۸, China
Jiqin Lian - Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Third Military Medical University, Chongqing ۴۰۰۰۳۸, China

Objective(s): Autophagy-related ۴B (ATG۴B) plays an important role in the process of autophagy induction. However, the molecular events that govern the expression of ATG۴B in this process are not well known. Materials and Methods: Human ATG۴B ۳'-UTR region (۱۳۷۷ nt) containing miR-۳۴a/miR-۳۴c-۵p binding site was amplified by PCR. Luciferase assay was used to assess the activity of reporter genes. Real-time PCR was used to detect the levels of miR-۳۴a and miR-۳۴c-۵p. Western blot was used to analyze the protein levels of ATG۴B, LC۳ and p۶۲. Results: Both miR-۳۴a and miR-۳۴c-۵p could directly target the ۳'-UTR of ATG۴B mRNA at same site. Overexpression of either miR-۳۴a or miR-۳۴c-۵p significantly down-regulated ATG۴B at both mRNA and protein levels and this effect can be reversed by ATG۴B overexpression. Moreover, Rapamycin-induced autophagy is accompanied with the upregulation of ATG۴B and the downregulation of miR-۳۴a/miR-۳۴c-۵p. Ectopic expression of either miR-۳۴a or miR-۳۴c-۵p markedly suppressed rapamycin-triggered autophagy. Conclusion: In the present study, we found that miR۳۴/ATG۴B signaling axis involves in rapamycin-triggered autophagy. This study may provide a new insight for understanding the mechanisms of ATG۴B regulation and autophagy induction.

Autophagy, ATG۴B, MiR-۳۴a, miR-۳۴c-۵p, Rapamycin