Can genetic variation in microRNA sequences impact on the normal function of the pancreatic beta cell?. (360G-Wellcome-089845_Z_09_Z)

Small regulatory RNA species are important in the fine control of gene expression, which may have implications for complex diseases like diabetes. MicroRNAs are endogenously coded throughout the genome and exhibit genetic variation like other genes. We will determine whether single nucleotide polymorphisms (SNPs) in mature miRNAs or in their precursors (pre-miRNAs) can influence microRNA processing, microRNA structure or target gene regulation. We will determine the microRNA expression profile o f human islets from normal and type 2 diabetic subjects and those in islets from db/db and control mice. MicroRNAs that are found to be deregulated in diabetes and those known from the literature to be important in endocrine function will be screened for sequence variants in regions important for target recognition or miRNA processing. We have already identified two potential variants in the islet-specific miR-375, and miR-376b genes. We will determine the target genes for newly-identified SNPs both in silico and empirically, followed by in vitro knockdown of each allele in isolated beta cells. This will allow us to determine the effect of polymorphisms on target gene expression, microRNA stability and on measures of beta-cell function like glucose-stimulated insulin release, ATP production and intracellular calcium flux.