Unraveling the effects of 1,25(OH)2D3 on global gene expression in pancreatic islets

Abstract Introduction Vitamin D deficiency has been linked to type 1 and 2 diabetes, whereas supplementation may prevent both diseases. However, the extent of the effects of vitamin D or its metabolites directly on pancreatic islets is still largely unknown. The aim of the present study was to investigate how active vitamin D, 1,25(OH) 2 D 3 , affects beta cells directly by establishing its effects on global gene expression in healthy murine islets. Materials and methods Pancreatic islets were isolated from 2 to 3 week old C57BL/6 mice and cultured in vitro with 1,25(OH) 2 D 3 or vehicle for 6 and 24 h. Total RNA was extracted from the islets and the effects on global gene expression were analyzed using Affymetrix microarrays. Results and discussion Exposure to 1,25(OH) 2 D 3 compared to vehicle resulted in 306 and 151 differentially expressed genes after 6 and 24 h, respectively ( n  = 4, >1.3-fold, p 2 D 3 on glucose-stimulated insulin release from healthy pancreatic islets. Conclusion The effects of 1,25(OH) 2 D 3 on the expression of cytoskeletal and intracellular trafficking genes along with genes involved in ion transport may influence insulin exocytosis. However, an effect of 1,25(OH) 2 D 3 on insulin release could not be detected for healthy islets in contrast to islets subjected to pathological conditions such as cytokine exposure and vitamin D deficiency as suggested by other studies. Thus, in addition to previously identified tolerogenic effects on the immune system, 1,25(OH) 2 D 3 may affect basic functions of pancreatic beta cells, with the potential to render them more resistant to the detrimental conditions encountered during type 1 and 2 diabetes. This article is part of a Special Issue entitled ‘Vitamin D Workshop’.