A microarray-based method to profile global microRNA expression in human and mouse.

The microRNAs (or miRNAs) are small noncoding RNAs (21-25 nt) that are processed from large hairpin RNA precursors and are believed to be involved in a wide range of developmental and cellular processes, by either repressing translation or triggering mRNA interference (RNA interference). Over 200 of distinct genes encoding miRNAs have been identified through either computer-assisted approaches or complementary deoxyribonucleic acid cloning strategies in many organisms including worm, plants, flies, mouse, and human. Recently, a microarray based robust method to profile miRNAs expression in organs cell lines and tissues in mammalians were developed (1). Using this method, we have identified a group of miRNAs preferentially expressed in human primary adipocytes and knocking down one such miRNA (miRNA 143) reverses the differentiation process (2). Groups of kidney specific miRNAs share evolutionary conserved phylogenetic foot print Ets 1 in the upstream of the miRNA, possibly important for kidney physiological maintenance were reported. A detail protocol of the method are discussed to develop miRNA profile for global gene expression in tissues, organs, and cell lines in eukaryotes.