Mid1 promotes synovitis in rheumatoid arthritis via ubiquitin-dependent post-translational modification.
Pharmacol Res
; 205: 107224, 2024 Jul.
Article
in En
| MEDLINE
| ID: mdl-38777113
ABSTRACT
INTRODUCTION:
Current anti-rheumatic drugs are primarily modulating immune cell activation, yet their effectiveness remained suboptimal. Therefore, novel therapeutics targeting alternative mechanisms, such as synovial activation, is urgently needed.OBJECTIVES:
To explore the role of Midline-1 (Mid1) in synovial activation.METHODS:
NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice were used to establish a subcutaneous xenograft model. Wild-type C57BL/6, Mid1-/-, Dpp4-/-, and Mid1-/-Dpp4-/- mice were used to establish a collagen-induced arthritis model. Cell viability, cell cycle, qPCR and western blotting analysis were used to detect MH7A proliferation, dipeptidyl peptidase-4 (DPP4) and Mid1 levels. Co-immunoprecipitation and proteomic analysis identified the candidate protein of Mid1 substrates. Ubiquitination assays were used to determine DPP4 ubiquitination status.RESULTS:
An increase in Mid1, an E3 ubiquitin ligase, was observed in human RA synovial tissue by GEO dataset analysis, and this elevation was confirmed in a collagen-induced mouse arthritis model. Notably, deletion of Mid1 in a collagen-induced arthritis model completely protected mice from developing arthritis. Subsequent overexpression and knockdown experiments on MH7A, a human synoviocyte cell line, unveiled a previously unrecognized role of Mid1 in synoviocyte proliferation and migration, the key aspects of synovial activation. Co-immunoprecipitation and proteomic analysis identified DPP4 as the most significant candidate of Mid1 substrates. Mechanistically, Mid1 promoted synoviocyte proliferation and migration by inducing ubiquitin-mediated proteasomal degradation of DPP4. DPP4 deficiency led to increased proliferation, migration, and inflammatory cytokine production in MH7A, while reconstitution of DPP4 significantly abolished Mid1-induced augmentation of cell proliferation and activation. Additionally, double knockout model showed that DPP4 deficiency abolished the protective effect of Mid1 defect on arthritis.CONCLUSION:
Overall, our findings suggest that the ubiquitination of DPP4 by Mid1 promotes synovial cell proliferation and invasion, exacerbating synovitis in RA. These results reveal a novel mechanism that controls synovial activation, positioning Mid1 as a promising target for therapeutic intervention in RA.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Arthritis, Experimental
/
Arthritis, Rheumatoid
/
Synovitis
/
Protein Processing, Post-Translational
/
Dipeptidyl Peptidase 4
/
Ubiquitin-Protein Ligases
/
Mice, Inbred C57BL
Limits:
Animals
/
Humans
/
Male
Language:
En
Journal:
Pharmacol Res
Journal subject:
FARMACOLOGIA
Year:
2024
Document type:
Article