Small RNA sequencing in healthy human tissues and brain tumor samples

The objective of the study was to identify spectrum of miRNA editing in diverse healthy human tissues, especially in human brain. For this we obtained paired tissues from six individuals, viz. frontal cortex (FC; rich in neuronal cell bodies) and corpus callosum (CC; devoid of neuronal cell bodies). These are post-mortem samples from road accident victims. Other in-house samples included total RNA from brain samples, testes and ovary. Small RNA sequencing was done using Illumina Tru-Seq chemistry on Hi-Seq2000 platform (50 bases single end). 3'-adaptors were trimmed from the sequencing reads and aligned against the genome using Bowtie 0.12.7. Glioblastoma Multiforme (GBM) samples were sequenced in the same way and compared with healthy brain samples. Brain showed more A-to-I editing than other tissue types, within brain FC showed more editing than CC of the same individuals whereas GBM samples showed hypoediting as compared to CC samples.