Adhikari, Neeta

MicroRNAs are a class of small non-coding RNAs that regulate gene expression by binding to discrete sites of genes and inhibiting translation. The objective of this study was to identify microRNAs and downstream enriched targets associated with symptomatic carotid plaques. Carotid plaque samples from patients were defined as symptomatic if they were associated with a prior ischemic stroke or transient ischemic attack, or as asymptomatic if there were no prior ischemic events. Digital microRNA profiling was performed on the NanoString nCounter analysis system (NanoString Technologies, Seattle, WA) on carotid plaques from symptomatic (n=6) and asymptomatic (n=6) patients. We used the BioConductor/R package "edgeR" to perform moderated-ANOVA testing for differences in gene abundance between groups, assuming a negative binomial distribution of gene counts, with Benjamini-Hochberg multiple hypothesis correction to control false discovery rate. Analysis revealed five microRNAs that were significantly up-regulated in the symptomatic cohort (see Table 1) including miR-16, which was confirmed by RTqPCR (p=0.02). Predicted downstream targets of miR-16 were enriched for proteoglycan related genes including hyaluronan synthase 2, perlecan and betaglycan. Additionally, RTqPCR demonstrated up-regulation of CathepsinB transcript in symptomatic patients (n=46-50 per cohort, p=0.02) while CathepsinL and heparanase transcripts were not significantly different. CathepsinL enzyme activity was also not significantly different (n=46-50 per cohort). Taken together, these findings may reveal novel proteoglycan mediated signaling pathways, mediated through miR-16, regulating the progression of carotid plaque formation.