The level of AGO binding of a particular miRNA is a better indicator of its inhibitory potential compared to its total cellular expression level 5. Mature miRNAs most often function as RISCs bound to the AGO proteins to modulate the expression of their target coding RNAs 3, 4. One of the strands of the duplex is embedded into Agronaute (AGO) protein to form the miRNA-induced silencing complex (miRISC) 2. Pre-miRNA is exported to cytoplasm and further processed by the RNase III domain of Dicer into 18–25 base pair miRNA-5p/miRNA-3p duplex. These transcripts are further processed in the nucleus by the RNase III domain of endoribonuclease Drosha into precursor miRNA (pre-miRNA). miRNAs are first transcribed as primary transcripts (pri-miRNAs) by RNA polymerase II or polymerase III. MicroRNAs are 18–25 nt non-coding small RNAs that post-transcriptionally regulate gene expression by inducing destabilization and degradation of specific mRNA targets and/or by repressing their translation 1. These findings will provide an insight to the miRNA-mediated control of gene expression in the pathogenesis of OA. Here, we also show the changes in miRNA composition of the miRISC in primary human chondrocytes in response to IL-1β treatment. Together, these results reveal a complex repertoire of miRNAs and isomiRs in primary human chondrocytes. AGO2 RIP-Seq analysis revealed the differential recruitment of a subset of expressed miRNAs and isoforms of miRNAs (isomiRs) to the miRISC in response to IL-1β, including miR-146a-5p, miR-155-5p and miR-27b-3p.
miR-27b-3p showed the highest expression and miR-140-3p showed the highest number of sequence variations. We found a number of miRNAs that showed a wide range of sequence modifications including nucleotide additions and deletions at 5′ and 3′ ends and nucleotide substitutions. IL-1β treatment showed a modest effect on the expression profile of miRNAs in normal and osteoarthritis (OA) chondrocytes. We characterized the dynamic repertoire of the chondrocyte miRNome and miRISC-associated miRNome by deep sequencing analysis of primary human chondrocytes. MicroRNAs, a group of small, noncoding RNAs that post-transcriptionally regulate gene expression, play important roles in chondrocyte function and in the development of osteoarthritis.
0 kommentar(er)
