MicroRNA profiling of diverse endothelial cell types

We identified 166 expressed miRNAs, of which 3 miRNAs (miR-99b, miR-20b and let-7b) differed significantly between EC types and predicted EC clustering. We confirmed the significance of these miRNAs by RT-PCR analysis and in a second data set by Sylamer analysis. We found wide diversity of miRNAs between endothelial, epithelial and hematologic cells with 99 miRNAs shared across cell types and 31 miRNAs unique to ECs. We show polycistronic miRNA chromosomal clusters have common expression levels within a given cell type.EC miRNA expression levels are generally consistent across EC types. Three microRNAs were variable within the dataset indicating potential regulatory changes that could impact on EC phenotypic differences. MiRNA expression in endothelial, epithelial and hematologic cells differentiate these cell types. This data establishes a valuable resource characterizing the diverse miRNA signature of ECs.MicroRNAs (miRNAs) are highly conserved ~22 nt long regulatory RNAs. Critical modulators of post-transcriptional gene regulation, miRNAs bind to 3' UTR regions of mRNAs, where they function to block translation and decrease mRNA stability. To date, over 800 miRNAs have been identified in the mammalian genome. The diversity of these miRNAs and the regulatory roles they have in different cell types are just beginning to be explored.Hundreds of studies have been performed investigating miRNA expression differences by array, deep RNA sequencing or qRT-PCR methods. Generally these studies either compare normal tissue to a diseased/malignant/perturbed state or developmental tissues over a time course [1-3]. There are fewer studies investigating miRNA expression patterns in normal tissues. A pioneering experiment investigated miRNAs from the heart, liver, spleen, small intestine, colon and brain of mice, identifying several "organ specific" miRNAs [4]. A second study of 24 human organs confirmed and expanded on these initial findings. It also demonstrated that miRNA exp