Abstract: Objective: To investigate the regulatory effect of miRNA on chronic masticatory myalgia(CMM). Methods: Twenty-three CMM patients were recruited from the Center for TMD and Orofacial Pain of Peking University School and Hospital of Stomatology, 23 gender- and age- matched healthy people recruited as control group. A total of 2 mL peripheral blood was collected from each participant of two groups. MiR-15a-5p and miR-19b-3p were preliminarily screened out as target miRNAs which are associated with CMM by regulating MEK3 according to Targetscan database and DIANA database in the previous experiments. QRT-PCR was used to select the possible miRNA further. Subsequently, the cell transfection and miRNA-overexpression experiment were conducted to verify the relationship of miRNA and MEK3 gene with qRT-PCR and Western blot. Results: MiR-19b-3p expressions were significantly decreased in CMM group compared to healthy control group using qRT-PCR assays (P<0.05), and miR-15a-5p expressions were not significantly different between these two groups(P>0.05). MiR-19b-3p was selected to verify the relationship between miRNA and MEK3 gene in the following experiments. The results showed that the mRNA and protein of MEK3 gene had no significant difference between miR-19b-3p-overexpression group and miR-NC group in human leukemia monocytic cell line (THP-1 cell) at 24h、48h and 72h ( P>0.05). Conclusions: MiR-19b-3p may be involved in CMM and its mechanism is likely to be complicated. It may not work by binding to the MEK3 gene directly.

Key words: miR-19b-3p, MEK3, chronic masticatory myalgia