Prepatterning of NPC developmental competence. During the fate-specification process, regulatory elements of lineage specification genes in multipotent NPCs are prepatterned with distinct chromatin marks. This epigenetic prepatterning primes the lineage competence of NPCs. Upon stimulation by developmental cues, these lineage-primed NPCs readily initiate transcription programs that are transcriptionally prepatterned, but protein expression of lineage specification genes is suppressed by two mechanisms. RNA degradation by m6A mRNA modification and translational repression by Pum2–4E-T complex provide gate-keeping systems to prevent the precocious activation of the lineage specification program. This transcriptional prepatterning potentially contributes a rapidly induced and fine-tuned cell fate specification process from multipotent progenitors in different tissues.
