Single-Cell Transcriptome Profiling of Pancreatic Islets From Early Diabetic Mice Identifies Anxa10 for Ca²⁺ Allostasis Toward β-Cell Failure

Type 2 diabetes is a progressive disorder denoted by hyperglycemia and impaired insulin secretion. Although a decrease in β-cell function and mass is a well-known trigger for diabetes, the comprehensive mechanism is still unidentified. Here, we performed single-cell RNA sequencing of pancreatic islets from prediabetic and diabetic db/db mice, an animal model of type 2 diabetes. We discovered a diabetes-specific transcriptome landscape of endocrine and nonendocrine cell types with subpopulations of β-and α-cells. We recognized a new prediabetic gene, Anxa10, that was induced by and regulated Ca²⁺ influx from metabolic stresses. Anxa10-overexpressed β-cells displayed suppression of glucose-stimulated intra-cellular Ca²⁺ elevation and potassium-induced insulin secretion. Pseudotime analysis of β-cells predicted that this Ca²⁺-surge responder cluster would proceed to mitochondria dysfunction and endoplasmic reticulum stress. Other trajectories comprised dedifferentiation and transdifferentiation, emphasizing acinar-like cells in diabetic islets. Altogether, our data provide a new insight into Ca²⁺ allostasis and β-cell failure processes.