NEDD4L knockdown enhances synovial fibroblast migration, invasion, and inflammatory factor secretion via...

This study aimed to elucidate the role of neuronaI precursor cell-expressed developmentally down-regulated 4-like (NEDD4L), a developmentally downregulated E3 ubiquitin ligase, in rheumatoid arthritis (RA).

Serum NEDD4L levels in RA patients (during both stable and active disease stages) and healthy controls were measured by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry (IHC) was used to analyze NEDD4L expression in synovial tissues from RA patients compared to traumatic control subjects. In animal experiments, the proteasome inhibitor MG-132 was administered to inhibit NEDD4L degradation, and its effects on joint inflammation and bone erosion were evaluated in a collagen-induced arthritis (CIA) rat model. At the cellular level, NEDD4L overexpression and knockdown models were constructed in rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs). The effects of NEDD4L on RA-FLS proliferation, migration, and invasion were assessed using CCK-8, wound healing and Transwell assays, respectively. Transcriptome analysis of the NEDD4L-knockdown model provided further insights into the associated diseases and pathways. Finally, the impact of NEDD4L on key proteins of the Wnt/β-catenin signaling pathway (DVL2, GSK3β, p-GSK3β, β-catenin) was examined via Western blotting and immunofluorescence, systematically investigating the mechanism of NEDD4L in RA pathogenesis both in vivo and in vitro.

NEDD4L expression was downregulated in the serum and synovial tissues of RA patients. Functional assays demonstrated that NEDD4L knockdown enhanced the proliferative, migratory, and invasive capacities of RA-FLSs and promoted the secretion of the pro-inflammatory cytokines IL-6 and TNF-α, whereas NEDD4L overexpression exerted opposite effects. In CIA rats, MG-132 intervention alleviated joint inflammation and bone destruction, concomitant with restored synovial NEDD4L expression. Mechanistic studies further revealed that NEDD4L influences the biological behavior of RA-FLSs by regulating key components of the Wnt/β-catenin signaling pathway.

NEDD4L modulates the migration, invasion, and pro-inflammatory cytokine secretion of RA-FLSs via the Wnt/β-catenin signaling pathway, suggesting its potential as a therapeutic target for RA. Key Points • NEDD4L knockdown activates Wnt/β-catenin pathway (DVL2, GSK3β, β-catenin). • Promotes IL-6/TNF-α secretion and cell invasiveness. • NEDD4L overexpression shows opposite effects. • Potential therapeutic target for RA.