Differential expression of circulating microRNAs in diabetic and healthy lean cats

MicroRNAs (miRNAs) regulate gene expression and play a role in the pathogenesis of human type 2 diabetes mellitus. This study investigated whether miRNA expression profiles differ between healthy and diabetic cats. Total RNA was extracted from sera of healthy lean cats, newly diagnosed diabetic cats and cats in diabetic remission. Microarrays representing 1079 mouse miRNA targets were used to measure miRNA expression in serum samples from eight healthy lean and seven newly diagnosed diabetic cats; 227 distinct miRNAs could be detected. Nineteen miRNAs were differentially expressed in newly diagnosed diabetic cats compared to healthy lean cats, with a false discovery rate of 10%. Hierarchical cluster analysis of these 19 miRNAs grouped healthy lean and newly diagnosed diabetic cats into separate clusters. After correction for multiple testing, only miR-122 and miR-193b reached statistical significance (P<0.05), with a false discovery rate of 1%. Specific quantitative real-time PCR assays for three target miRNAs (miR-122, miR-193b and miR-483(*)) were applied to four samples from each of the three groups. miR-122 expression was >40-fold higher in newly diagnosed diabetic cats compared to healthy lean cats and cats in diabetic remission, whereas miR-193b showed >14-fold higher expression. MiR-483(*) was expressed sixfold higher in newly diagnosed diabetic cats compared to both other groups.