Construction of small RNA cDNA libraries for deep sequencing

Small RNAs (21–24 nucleotides) including microRNAs (miRNAs) and small interfering RNAs (siRNAs) are potent regulators of gene expression in both plants and animals. Several hundred genes encoding miRNAs and thousands of siRNAs have been experimentally identified by cloning approaches. New sequencing technologies facilitate the identification of these molecules and provide global quantitative expression data in a given biological sample. Here, we describe the methods used in our laboratory to construct small RNA cDNA libraries for high-throughput sequencing using technologies such as MPSS, 454 or SBS.