Regulation of nuclear transport of the transcriptional factor REST improves axon regeneration in peripheral nerves.

Abstract

The expression of repressor element 1 silencing transcription factor (REST) in peripheral nerves increases with age, which leads to a decline in axon regeneration. However, the detailed mechanisms behind the decline in axon regeneration with age remain to be elucidated. The present study investigated the mechanism of nuclear transport of REST using hydrogen (H₂), which has neuroprotective effects. First, aged mice as an animal model and REST‑overexpressed (REST‑OE) cells generated from the NIH‑3T3 fibroblast cell line as a cellular model were treated with H₂ to examine REST expression and growth‑associated protein 43 (GAP43) as an axon regeneration marker. Subsequently, to examine differences in the localization of REST expression, in vitro cell lines were fractionated into cytoplasmic and nuclear fractions for immunofluorescence staining and western blotting, and REST expression was quantified. Furthermore, to investigate the mechanisms of nuclear transport, REST nuclear transport proteins (REST‑interacting LIM domain protein, Huntingtin and dynactin subunit 1/p150^Glued) and the autophagy‑related protein LC3 were semi‑quantified by western blotting. REST expression was decreased, and GAP43 expression was increased following H₂ administration in animal models and REST‑OE cells. REST intracellular localization analysis revealed that REST expression was significantly increased in the cytoplasm and significantly decreased in the nucleus in the REST‑OE + H₂ group compared with the REST‑OE group. Furthermore, the present findings revealed that the addition of H₂ resulted in a significant decrease in several REST nuclear transport proteins, subsequently suppressing the nuclear translocation of REST. These findings suggest that regulation of the nuclear transport of REST by H₂ improves the decline in axon regeneration.