Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D

Objective: Dedifferentiation of pancreatic beta-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 alpha- and beta-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals. Results: Both alpha- and beta-cells mature in part by repressing non-endocrine genes; however, alpha-cells retain hallmarks of an immature state, while beta-cells attain a full beta-cell specific gene expression program. In islets from T2D donors, both alpha- and beta-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 beta-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. (C) 2020 The Author(s). Published by Elsevier GmbH.