Apical-basal polarity drives pancreatic alpha/beta cell fate allocation

A central question in cell and developmental biology is how extracellular cues control the differentiation of multipotent progenitors in a dynamically changing niche. Here, we identify apical-basal polarity as the main regulator of the differentiation of multipotent pancreatic Neurogenin3+ endocrine progenitors (EPs) into the beta or alpha cell fates. We show that human EPs dynamically change their apical-basal polarity status. Whereas polarized EPs are predisposed to differentiate into beta cells rather than alpha cells, inhibiting apical-basal polarity selectively suppresses beta cell differentiation. Single-cell RNA sequencing and complementary mechanistic data demonstrate that apical-basal polarity in human EPs promotes beta cell specification via cyclic AMP (cAMP)/PKA-cAMP response element binding protein (CREB)-EGR1-mediated inhibition of ARX expression, while reduced cAMP levels in non-polarized human EPs maintain expression of ARX, leading to alpha cell differentiation. These findings identify the apical-basal polarity status of multipotent EPs as a critical epithelial feature that determines their fate into the alpha or beta cell lineages. We performed scRNA sequencing to understand how apical-basal polarity drives pancreatic alpha/beta cell fate allocation. We combined this technology to CITE-sequencing and HASH-sequencing in order to measure these data simultaneously in early/late and polarized/unpolarized endorine progenitors.