Strategies to determine the biological function of microRNAs

Abstract

MicroRNAs (miRNAs) are regulators of gene expression that control many biological processes in development, differentiation, growth and metabolism. Their expression levels, small size, abundance of repetitive copies in the genome and mode of action pose unique challenges in studies elucidating the function of miRNAs. New technologies for identification, expression profiling and target gene validation, as well as manipulation of miRNA expression in vivo, will facilitate the study of their contribution to biological processes and disease. Such information will be crucial to exploit the emerging knowledge of miRNAs for the development of new human therapeutic applications.

Diverse Ways to Control p27Kip1 Function: miRNAs Come into Play

“…Recently, expression profiling addressed the differential expression of most known miRNAs in different tissues, cell lines and developmental stages. [21][22][23][24] However, most of the biologically-relevant miRNA targets are still unknown. The identification of miRNA targets in animals has been hampered by the fact that these miRNAs bind only with partial complementarity to their targets, in contrary to their counterparts in plants.…”

Searching for potential microRNA-binding site mutations amongst known disease-associated 3′ UTR variants

“…The only known pathological mutation in an miRNAtarget site, a G > A transition in the 3¢ UTR of the SLITRK1 gene in two patients with Tourette's syndrome (Abelson et al 2005), is included for the sake of comparison sequence and its mutated counterpart, each of total length~50 bp flanking the site of mutation, were screened for the presence of miRNA binding sites, with all possible 25 bp fragments within these flanking sequences being examined sequentially. Krutzfeldt et al 2006), miRNA-target sites within the 3¢ UTRs of human protein-coding genes constitute a new class of cis-acting regulatory elements. Although the mechanism underlying miRNA-target site interactions still remains to be elucidated, it is clear that the initiation of target site recognition often relies on short stretches (6-8 bp) of perfect (and consecutive) Watson-Crick miRNA-mRNA complementarity; this perfect match is typically located at the 5¢ end of the miRNA (termed the 'seed' site; Lewis et al 2003Lewis et al , 2005Bentwich 2005;Brennecke et al 2005;Rajewsky 2006).…”

MicroRNAs in Solid Tumors

“…In another study, injection of antogmiR-16, which is ubiquitously expressed, led to complete absence of miR-16 everywhere except the brain in a mouse model. Genetic alterations can also be used to knock out miRNA genes directly or via conditional alleles, leading to a nonfunctional Dicer and the resultant silencing of miRNAs [48]. While the use of miRNA alteration has not made the leap to the clinical setting, such advancements are forthcoming.…”