miRNA profiling of bilateral rat hippocampal CA3 by deep sequencing.

MicroRNAs (miRNAs) have been demonstrated to be potent post-trascriptional modulators of protein expression. miRNA expression was profiled in the left and right dorsal hippocampal CA3 of mature rats by high-throughput deep sequencing. Among the sequenced and cross-mapped small RNAs, 88% belonged to the miRNAs annotated in the miRBase 15 database. Nearly half of the small RNAs belonged to the let-7 family miRNA. Seven percent of the sequenced small RNAs were not annotated in miRBase 15. Bioinformatic analysis of the unannotated small RNA sequences suggested seventeen novel miRNA candidates with relatively high expression levels (>100 tags per million). The left:right expression ratios were similar for all highly expressed miRNAs with less than 10% differences. These results provide a basic idea of the relative expression strengths of known and unknown miRNAs in the dorsal hippocampal CA3.