Daily Endocrinology Research Analysis

Diabetic foot ulcers are severe diabetic complications, and promoting impaired angiogenesis is essential for wound healing. Pro-angiogenic galectin-3 is elevated in diabetic serum and promotes systemic insulin resistance that may impair wound healing. However, the exact role of galectin-3 in the regulation of diabetic wound healing remains unclear. Here, we demonstrate that galectin-3 promotes skin wound healing and angiogenesis via binding to its receptor integrin α5β1, and enhances downstream focal adhesion kinase phosphorylation by forming a liquid-liquid phase separation with integrin α5β1. Under diabetic conditions, aberrant accumulated advanced glycation end-products bind to galectin-3, blocking its interaction with integrin α5β1 and impairing angiogenesis. Topical treatment of recombinant galectin-3 in hydrogels promotes diabetic wound healing in rodents without causing systemic insulin resistance and synergizes with insulin. This study clarifies the binding of galectin-3 to integrin α5β1, instead of advanced glycation end-products, forming phase separation to promote angiogenesis and diabetic wound healing, laying the foundation for local galectin-3 therapy to treat diabetic foot ulcers.

Type 2 diabetes (T2D) is a devastating chronic disease marked by pancreatic β cell dysfunction and insulin resistance, whose pathophysiology remains poorly understood. HNF1A, which encodes transcription factor hepatocyte nuclear factor-1 alpha, is the most commonly mutated gene in Mendelian diabetes. HNF1A also carries loss- or gain-of-function coding variants that respectively predispose to or protect against polygenic T2D. The mechanisms underlying HNF1A-deficient diabetes, however, are still unclear. We now demonstrate that diabetes arises from β cell-autonomous defects and identify direct β cell genomic targets of HNF1A. This uncovered a regulatory axis where HNF1A controls transcription of A1CF, which orchestrates an RNA splicing program encompassing genes that regulate β cell function. This HNF1A-A1CF transcription-splicing axis is suppressed in β cells from T2D individuals, while genetic variants reducing pancreatic islet A1CF are associated with increased glycemia and T2D susceptibility. Our findings, therefore, identify a linear hierarchy that coordinates β cell-specific transcription and splicing programs and link this pathway to T2D pathogenesis.

Islet-resident macrophages contribute to hypoxia-induced islet cell death during pancreatic islet transplantation. However, their specific role during this process remains elusive. Here, we report that interleukin-1α (IL-1α) and IL-1β are released by islet-resident macrophages, resulting in the suppression of insulin secretion. This may be due to a decreased inflammation-driven expression of pancreatic and duodenal homeobox 1 (PDX-1) and MafA in β cells. Islet-resident macrophages release significantly less IL-1α when compared to IL-1β. However, both cytokines inhibit insulin expression and secretion to a comparable extent. We identified heparan sulfate on the islet surface, which acts as a "molecular glue" potentiating the inhibitory action of IL-1α on insulin expression via specific binding to IL-1 receptor (IL-1R). In vivo analyses revealed that the loss of IL-1 signaling in isolated islets accelerates their revascularization and, thus, enhances their endocrine function. These findings indicate that heparan sulfate fine-tuned IL-1 signaling crucially determines the outcome of islet transplantation.