Constructing chimeric mouse islets to study alpha- and delta-cell influence on beta-cell feature.

Objectives: This study aimed to evaluate the role of alpha- and delta-cell signals on beta-cells within pancreatic mouse islets. Specifically, we investigated how these signals regulate glucose sensitivity, gene expression and function in beta-cells.

Methods: We first implemented our previous protocol to FACS purify alpha-, beta-, and delta-cells by adding CD81 as a positive marker for alpha-cells. We next developed an approach to reaggregate these sorted cell populations, creating chimeric islets with different proportions of each endocrine cell type. We used these chimeric islets to study the effect of alpha- and delta-cells on glucose sensitivity, gene expression and function in beta-cells.

Results: We generated chimeric islets containing either all three endocrine cell types, alpha- + beta-cells or only beta-cells. We demonstrate that beta-cell glucose sensitivity and identity are independent of signals from alpha- and delta-cells. We identified a subset of genes including Pro-dynorphin, Fumarate hydratase and Txnip whose expression in beta-cells depends on alpha-cells signals acting through the glucagon- and glucagon-like peptide receptors. Finally, we demonstrated that in mouse beta-cell, KCl-mediated insulin secretion relies on an activation of the glucagon-receptor, while glucose-stimulated insulin secretion depends on glucagon-like peptide receptor activation.

Conclusions: We developed an innovative and easy-to-use model to reconstruct chimeric islets containing different frequencies of alpha-, beta- and delta-cells. Through this approach, we provide new insights into the complex regulatory mechanisms governing the role of alpha and delta cells on beta-cell features within islets.