Acknowledgements
We thank Nan Hee Choi for technical assistance, Pamela Raymond for zebrafish gfap regulatory elements, Koichi Kawakami for mini-Tol2 (T2AL200R150G) plasmid, Eun Jin Kim for transmission electron microscopy and Eun Young Choi for encouragement.

Funding
This work was supported in part by grants from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013-R1A1A1058252), the Chonnam National University Hospital Biomedical Research Institute (CRI 12055–21 and CRI 13902–24), and the Chonnam National University Hwasun Hospital Biomedical Research Institute (HCRI 15013–21). These funding sources had no role in the design of the study and collection, analysis, and interpretation of data.

Availability of data and materials
All data generated or analyzed during this study are available from the corresponding authors on reasonable request.