Identification of a cartilage specific novel miRNA which directly targets PRMT3 in rats

Through experiments to testify a candidate novel miRNA previously discovered by us is a real miRNA and involved in cartilage development.

The miR-novel and the newly hairpin miRNA transcribed sequence (pre-miR-novel) was verified as a genuinely existing miRNA by northern blotting. The predicted secondary structure, sequence alignment and targets of pre-miR-novel were performed by "RNAstructure 5.3" program, LASTN2.8.0+/miRbase22 program and RNA hybird program, respective. GO/KEGG pathway analysis also were performed. The miR-novel expression in cartilage tissue during development was detected by RT-qPCR and dot blotting. The chondrocyte differentiation model was established to examine whether miR-novel is involved in cartilage development. The regulation of PRMT3 expression by novel miRNA was determined with the luciferase reporter gene assay and Western blotting after novel miRNA mimic or inhibitor transfection.

It's potential role in specifically regulating rodent cartilage development and associated cellular processes. Furthermore, the expression of protein arginine N-methyltransferase 3 (PRMT3), as a predicted target of the novel miRNA, was found consistently downregulated at rat cartilage during developmental stages and RCJ3.1C5.18 (C5.18) cells during the proliferating and hypertrophic phases of the cartilage development, where the miR-novel expression was significantly up-regulated. Both the dual-luciferase reporter gene assay and the up- or down-regulation of miR-novel suggest that the later can specifically bind with the Prmt3 3'-UTR.

Overall, this study provides the first comprehensive evidence that a genuine cartilage-specific novel miRNA directly targets PRMT3 and may regulate multitudinous cellular processes and signal transduction during cartilage development.