Roquin-1 interaction with Regnase-1 inhibits the progression of rheumatoid arthritis via suppressing FGF2 expression and NF-κB pathway.

Objective: This study aimed to explore the effect of Roquin-1 on rheumatoid arthritis (RA) and its potential mechanisms.

Methods: Firstly, we used TNF-α to stimulate fibroblast-like synoviocytes (FLSs) to establish an in vitro model of RA. Moreover, a rat model of RA was established with bovine type II collagen and complete Freund's adjuvant. EdU and transwell assays were applied for evaluating the proliferation and migration of FLSs. The multiple mRNA and proteins expressions in FLSs and rats synovial tissues were measured using qRT-PCR, ELISA, western blot, immunohistochemistry staining and immunofluorescence staining. Double immunofluorescence staining and co-IP assay were used to validate the protein interaction between Roquin-1 and Regnase-1. Additionally, cycloheximide (CHX) chase assay was applied for assessing the degradation of fibroblast growth factor 2 (FGF2). Besides, the state of synovial hyperplasia and articular cartilage were also evaluated using HE and Safranin O/Fast Green staining.

Results: The mRNA and protein expressions of Roquin-1 were significantly reduced in TNF-α-stimulated FLSs and the synovial tissues of RA rats. Roquin-1 interacted with Regnase-1 to promote FGF2 degradation and further inhibit the proliferation, migration and inflammation response in TNF-α-stimulated FLSs. Moreover, we also demonstrated that Roquin-1 interacted with Regnase-1 to inhibit NF-κB pathway via suppressing FGF2 expression in TNF-α-stimulated FLSs. In addition, Roquin-1 suppressed inflammatory response in RA rats.

Conclusion: Our findings demonstrated that Roquin-1 could interact with Regnase-1 to inhibit the progression of RA via suppressing FGF2 expression and NF-κB pathway.