Introduction: MicroRNAs in Health and Disease

MicroRNAs (miRNAs or miRs) are novel class of gene regulators, which, when produced by a cell, are able to turn off specific sets of genes through post-transcriptional mechanisms. They comprise a large family of small ~21-nucleotide long, non-coding RNAs that have been shown to control a variety of cellular processes such as cell proliferation, differentiation and apoptosis. Hence, aberrant expression of miRNAs is often observed in and functionally associated with various path-physiological conditions. MircroRNAs are capable of regulating a wide array of gene targets and therefore may exert diverse, highly potent and context-dependent functions. Past decade has witnessed considerable progress in miRNA research leading to identification of novel miRNA genes, validation of miRNA targets, and delineation of biological significance of miRNAs. To bring out this sepecial issue is an effort to sum up some of the knowledge gained during these past years and to discuss and envision the prospects of miRNAs in human health.Undoubtedly, miRNAs carry multi-faceted potential and the articles in this issue provide a glimpse of the breadth of this fascinating area of research.