LNA-FISH for detection of microRNAs in frozen sections

MicroRNAs (miRNAs) are small ( approximately 22 nt) noncoding RNA molecules that regulate the expression of protein coding genes either by cleavage or translational repression. miRNAs comprise one of the most abundant classes of gene regulatory molecules in multicellular organisms. Yet, the function of miRNAs at the tissue, cell, and subcellular levels is still to be explored. Especially, determining spatial and temporal expression of miRNAs has been a challenge due to their short size and low expression. This protocol describes a fast and effective method for detection of miRNAs in frozen tissue sections using fluorescence in situ hybridization. The method employs the unique recognition power of locked nucleic acids as probes together with enhanced detection power of the tyramide signal amplification system for detection of miRNAs in frozen tissues of human and animal origin within a single day.