ALKBH5 regulates somatic cell reprogramming in a phase-specific manner.

Establishment of the pluripotency regulatory network in somatic cells by introducing four transcription factors [octamer binding transcription factor 4 (OCT4; also known as POU5F1), sex determining region Y (SRY)-box 2 (SOX2), Kruppel-like factor 4 (KLF4) and cellular myelocytomatosis (c-MYC)] provides a promising tool for cell-based therapies in regenerative medicine. Nevertheless, the mechanisms at play when generating induced pluripotent stem cells from somatic cells are only partly understood. Here, we show that the RNA-specific N6-methyladenosine (m6A) demethylase ALKBH5 regulates somatic cell reprogramming in a stage-specific manner through its catalytic activity. Knockdown or knockout of Alkbh5 in the early reprogramming phase impairs reprogramming efficiency by reducing the proliferation rate through arresting the cells at G2/M phase and decreasing the upregulation of epithelial markers. On the other hand, ALKBH5 overexpression at the early reprogramming phase has no significant impact on reprogramming efficiency, whereas overexpression at the late phase enhances reprogramming by stabilizing Nanog transcripts, resulting in upregulated Nanog expression. Our study provides mechanistic insight into the crucial dynamic role of ALKBH5, mediated through its catalytic activity, in regulating somatic cell reprogramming at the post-transcriptional level. This article has an associated First Person interview with the first author of the paper.