miR­760 regulates skeletal muscle proliferation in rheumatoid arthritis by targeting Myo18b.

MicroRNAs serve an important role in the development of several diseases. Numerous genes regulate the skeletal muscle differentiation of C2C12 myoblasts. The role of miR­760 in rheumatoid arthritis (RA) has not been reported, to the best of our knowledge. Therefore, the aim of the present study was to examine the role of miR­760 in regulating skeletal muscle proliferation in RA. Potential genes functionally involved in the tarsal joint of a collagen­induced RA model were identified using Gene Expression Omnibus. Reverse transcription­quantitative PCR and western blot analyses were performed to determine the mRNA and protein expression levels. The proliferation, cell cycle progression and migration of C2C12 myoblasts were detected using Cell Counting Kit­8, flow cytometry and wound­healing assays, respectively. TargetScan was used to predict the potential target genes of miR­760, and this was verified using a dual­luciferase reporter assay. In the present study, myosin­18b (Myo18b) expression was determined to be downregulated in the RA model. Silencing Myo18b decreased the proliferation, abrogated the cell cycle progression, and reduced the migration and differentiation of C2C12 myoblasts. Expression levels of cyclin­dependent kinase 2, cyclin D1, matrix metalloproteinase (MMP)­2, MMP­9, myogenin and myosin heavy chain 6 were all decreased when Myo18b was silenced. Furthermore, overexpression of Myo18b induced opposing effects on C2C12 myoblasts. It was shown that Myo18b was a target gene of miRNA­760. Overexpression of miR­760 decreased proliferation, cell cycle progression, migration and differentiation in C2C12 myoblasts, and decreased the expression of Myo18b. The opposite results were observed when miR­760 was downregulated. In conclusion, miR­760 inhibited proliferation and differentiation by targeting Myo18b in C2C12 myoblasts. The results of the present study may contribute to understanding the mechanisms underlying RA skeletal muscle proliferation, and miR­760/Myo18b may serve as potential targets for treating patients with RA.

Screening for Key Pathways Associated with the Development of Osteoporosis by Bioinformatics Analysis.

Objectives. We aimed to find the key pathways associated with the development of osteoporosis. Methods. We downloaded expression profile data of GSE35959 and analyzed the differentially expressed genes (DEGs) in 3 comparison groups (old_op versus middle, old_op versus old, and old_op versus senescent). KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analyses were carried out. Besides, Venn diagram analysis and gene functional interaction (FI) network analysis were performed. Results. Totally 520 DEGs, 966 DEGs, and 709 DEGs were obtained in old_op versus middle, old_op versus old, and old_op versus senescent groups, respectively. Lysosome pathway was the significantly enriched pathways enriched by intersection genes. The pathways enriched by subnetwork modules suggested that mitotic metaphase and anaphase and signaling by Rho GTPases in module 1 had more proteins from module. Conclusions. Lysosome pathway, mitotic metaphase and anaphase, and signaling by Rho GTPases may be involved in the development of osteoporosis. Furthermore, Rho GTPases may regulate the balance of bone resorption and bone formation via controlling osteoclast and osteoblast. These 3 pathways may be regarded as the treatment targets for osteoporosis.