Mature and immature β-cells both contribute to islet function and insulin release

Abstract Transcriptionally mature and immature β-cells co-exist within the adult islet. How such diversity contributes to insulin release remains poorly understood. Here we show that differences in β-cell maturity, defined using PDX1 and MAFA expression, are required for proper islet operation. Functional mapping of rodent and human islets containing proportionally more mature β-cells revealed defects in metabolism, ionic fluxes and insulin secretion. At the transcriptomic level, the presence of increased numbers of mature β-cells led to dysregulation of gene pathways involved in metabolic processes. Using a chemogenetic disruption strategy, the islet signalling network was found to contribute to differences in maturity across β-cells. During metabolic stress, islet function could be restored by redressing the balance between immature and mature β-cells. Thus, preserving a balance between immature and mature β-cells might be important for islet engineering efforts and more broadly the treatment of type 1 and type 2 diabetes.