Abstract
Micro RNAs (miRNAs) represent a class of short, approximately 22nt long, single- stranded, endogenous and evolutionarily conserved, non-coding RNAs. These molecules postranscriptionally regulate the expression of structural genes.
By the mechanism of RNA interference (RNAi) they modulate stability and translational efficiency of target messenger RNAs. MiRNAs are found in various species, make up 1-2% of eukaryotic genomes and are predicted to affect the expression of about one-third of protein-coding genes.
By modulating protein levels in cells, they participate in regulation of key biological processes (cell growth, differentiation, proliferation, apoptosis). Recent findings highlight the crucial importance of miRNAs in development, homeostasis and function of innate and adaptive immunity.
Deregulation of miRNA expression is involved in pathogenesis of malignancies, heart diseases, neurodegenerative and inflammatory autoimmune disorders and infections. In systemic autoimmune diseases, miRNAs play a key role in regulation of major pathogenic molecules (TNF), central signaling pathways (IFN type I) and critical immunoregulatory cells (regulatory T cells).
MiRNA molecules have a considerable potential as a new class of therapeutic targets and diagnostic biomarkers. This article gives a brief overview of miRNA molecules, their role in the immune response and their relation to systemic autoimmune diseases.