The expression order determines the pioneer functions of Ngn3 and NeuroD1 in pancreatic endocrine differentiation

This study investigates the roles of Ngn3 and NeuroD1 in pancreatic endocrine differentiation. Using a new mouse model, we mapped NGN3 binding sites by CUT&RUN and demonstrated its pioneering role in making chromatin accessible by scATAC-seq. According to conditional knock-out and over-expression experiments and scRNA-seq, we domonstrated that NGN3's pioneering function was dose tolerance, with low doses sufficing, while NeuroD1, as a conventional TF, has no significant pioneer effects under normal phenomena. But when NGN3 was absent, NeuroD1 can alternatively acted as a pioneer factor, and sequential expression of NeuroD1 ahead of Ngn3 predominantly drives α-cell generation.