LAUSR

Objective Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. Methods We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals. Results Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets. Conclusions These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.