In a new study published in Journal of the American Chemical Society, Chen-Yu Zhang's group at Nanjing University reports photo-clickable miRNAs as probes for intracellular target identification of miRNAs.

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MiRNAs are a class of naturally occurring small non-coding RNAs that have been linked to biological possesses and diseases development. However, identification of target genes associated with miRNAs, which is the basic way to understand miRNA-involved cellular processes, is still a major challenge in miRNA chemical-biology due to the lack of functional miRNA bearing appropriate tags. In the present study, in order to overcome the limitation that 3'-biotinylation on miRNAs could cause loss of miRNA function, Chen-Yu Zhang and colleagues pre-tag miRNAs at the 3'-end with bio-orthogonal group that can undergo photo-click reaction. The photo-clickable miRNAs are able to form functional complexes with target genes upon delivery into cells and target genes associated with the photo-clickable miRNAs could be tagged with molecular handle through photo-click reaction for pull-down and identification.

This work is important for the following reasons:

1. This is the first time to demonstrate using biocompatible photo-click reaction to develop photo-clickable miRNAs for intracellular target identification. Current strategies for miRNA target identification mainly rely on bioinformatic methods, experimental methods to identify intracellular targets of miRNAs are in high demand. This is the first chemical-biology strategy for miRNA target identification.
2. The use of photo-clickable miRNAs may reveal more miRNA-involved cellular regulation pathways and more possible miRNA targets with pathological importance.