Abstract:

Autophagy-related gene 6 (Atg6) plays an essential role in autophagy, and loss of its function impairs neurogenesis. Planarian is a good model for the study of the central nervous system (CNS) regeneration. It can regenerate a new head de novo in 1 week following decapitation. Therefore, functional analysis of Atg6 in planarian CNS regeneration is very important for understanding of autophagy in the regulation of neurogenesis. In this work, we reported the molecular characteristics of Atg6 in Dugesia japonica (DjAtg6) for the first time and examined its function by RNAi. The full-length cDNA of DjAtg6 is 1366 bp encoding 423 amino acids. The deduced amino sequence of DjAtg6 contains the coil-coil domain and β-α-repeated autophagy-specific domain shared by ATG6/Beclin 1 family. Following amputation before and after the pharynx, DjAtg6 transcripts increased and were mainly distributed in the newly regenerated brain structure. RNAi-DjAtg6 delayed planarian head regeneration with a small size of brain, and decreased the expression levels of neural-related genes. In addition, our results revealed that RNAi-DjAtg6 did not affect the stem cell proliferation, but down-regulated the cell migration-related genes mmp1 and mmp2. Furthermore, RNAi-mmp1 and RNAi-mmp2 delayed planarian head regeneration. Therefore, our results suggest that DjAtg6 is important for planarian CNS regeneration. The abnormal CNS regeneration caused by RNAi-DjAtg6 may be related to cell migration, but the detailed mechanism needs to be further investigated.

Key words: planarian, autophagy, Atg6, regeneration, RNA interference