The protein-protein interaction between connective tissue growth factor and annexin A2 is relevant to pannus formation in rheumatoid arthritis

Abstract

Background Connective tissue growth factor (CTGF)-induced angiogenesis is a crucial factor in rheumatoid arthritis (RA), but CTGF-interacting protein and related molecular mechanism of their interaction have not been fully elucidated. Methods CTGF-interacting proteins were identified through the LC-MS/MS analysis of the Co-IP products from fibroblast-like synoviocyte (FLS) lysates, and the interaction between CTGF and annexin A2 (ANXA2) was further confirmed through Co-IP and BiFC assay. The binding domain, mutant, mechanism, and angiogenesis function were assessed by homology modeling, molecular docking, MTT, cell scratch, tube formation, and chick chorioallantoic membrane (CAM) assays. Additionally, severe combined immunodeficiency (SCID) mouse co-implantation model was constructed to confirm the effect of ANXA2/CTGF-TSP1 in the process of RA in vivo. Results ANXA2 was identified and verified as an interaction partner of CTGF for the first time by Co-IP and LC-MS/MS analysis. Co-localization of CTGF and ANXA2 was observed in RA-FLS, and direct interaction of the TSP-1 domain of CTGF and ANXA2 was determined in HEK293T cells. The spatial conformation and stable combination of the ANXA2/CTGF-TSP1 complex were assessed by homology modeling in the biomimetic environment. The function of the ANXA2/CTGF-TSP1 complex was proved on promoting FLS proliferation, migration, and angiogenesis in vitro and deteriorating FLS invasion and joint damage in SCID mice. Conclusions TSP-1 is the essential domain in CTGF/ANXA2 interaction and contributes to FLS migration and pannus formation, inducing the process of RA.

A fully human connective tissue growth factor blocking monoclonal antibody ameliorates experimental rheumatoid arthritis through inhibiting angiogenesis

“…We previously reported that CTGF relied on the TSP-1 domain to enhance angiogenesis [ 11 ], which plays a key role in pannus formation and maintenance in RA. Therefore, we investigated if IgG mut-B2 inhibits angiogenesis by binding to the TSP-1 domain.…”

“…Recent studies have gradually recognized that connective tissue growth factor (CTGF) plays a critical role in many pathogenic events of RA [ 11 – 15 ]. CTGF, also known as cellular communication network family member 2 (CCN2), is a cysteine-rich protein with four functional domains, including insulin-like growth factor binding protein (IGFBP), thrombospondin type 1 repeat (TSP-1), von Willebrand factor type C repeat (VWC), and C-terminal cystine-knot (CT) modules [ 14 ].…”

“…Research conducted by Nozawa et al has provided evidence that blockade of the CTGF pathway using a mouse monoclonal antibody can ameliorate collagen-induced arthritis (CIA) [ 13 ]. Our latest study has shown that TSP-1 is the essential domain for CTGF to enhance angiogenesis, which plays a vital role in forming and maintaining pannus in RA [ 11 ]. These results allowed CTGF to be a new antagonistic target, and anti-CTGF antibody may become an attractive option for RA treatment.…”

Organokines in Rheumatoid Arthritis: A Critical Review

“…The studies included in this review are from Italy [ 13 ], Egypt [ 14 , 15 , 16 ], Unites States [ 17 , 18 ], Mexico [ 19 , 20 , 21 , 22 ], Sweden [ 23 , 24 ], China [ 25 , 26 , 27 ], Turkey [ 28 ], and Finland [ 29 ]. One study was multicentered [ 14 ].…”

“…These cells are the main ones responsible for persisting the articular inflammation of the disease. Besides that there are proliferating synovial fibroblasts in RA, the inflammatory process also causes synovium hypertrophy, leading to the formation of an abnormal joint tissue called pannus, which not only invades but also destroys the articular structures locally by the production of pro-inflammatory chemokines and cytokines as well as of matrix MMPs [ 2 , 24 ].…”