Download Suppression of rat collagen-induced arthritis by lentiviral vector

Dissociation of the Inhibitory Apoptosis Stimulating Protein of p53 (iASPP)
Binding with Transcription Factor p73 Induces Synovial Fibroblast Apoptosis in
the Rheumatoid Joint
利用臨床檢體及關節炎模型來研究利用分離 iASPP 與轉錄因子 p73 鍵結以誘
導類風濕性關節滑膜纖母細胞的凋亡
Background: Apoptosis-resistant synovial fibroblasts (SFs) constitute the major cell
component of pannus tissues in rheumatoid arthritis (RA). In tumor cells, the binding
of inhibitory apoptosis stimulating protein of p53 (iASPP) with transcription factor
p53 family members can inhibit the downstream apoptosis signaling. We hypothesized
that iASPP molecule is involved in the RA pathogenesis, and examined whether
dissociation of such binding can induce SFs apoptosis in the rheumatoid joint.
Methods: Peripheral mononuclear cells (MNCs) from active RA before and after a
TNF inhibitor therapy and osteoarthritis (OA) patients were examined for their iASPP
expression by real-time RT-PCR. Synovial tissues and purified SFs from RA and OA
patients as well as normal and collagen-induced arthritis (CIA) rats were subjected to
immunohistochemical (IHC) and immunofluorescent staining for the expression of
iASPP and p73, a member of p53 family. SFs transfected with adenoviral vectors
encoding 37 amino acid (Ad37AA), a hybrid small peptide corresponding to p53
residues, were subjected to TUNEL assay and real-time RT-PCR for apoptotic status
and the expression of p53 upregulated modulator of apoptosis (PUMA), respectively.
The association of iASPP with p73 in Ad37AA-transfected SFs was identified by
anti-iASPP immunoprecipitation, followed by anti-p73 immunoblotting assay.
Therapeutic effects of intra-articular injection of Ad37AA on CIA joints were
evaluated by articular index and histological score. Further synovial IHC staining was
performed to analyze PUMA and IL-6 expression levels and SFs densities, and in situ
apoptotic cells in synovial tissues were detected by the TUNEL assay.
Results: There were reduced iASPP levels by targeting TNF in MNCs from RA
patients and increased iASPP levels with co-localized p73 expression in synovial
tissues and purified SFs from RA patients and CIA rats. Enhanced cell apoptosis and
increased PUMA expression were identified in Ad37AA-transfected SFs with lower
iASPP-associated p73 levels. Articular indexes and histologic scores were reduced in
Ad37AA-injected CIA joints with decreased SF densities, increased apoptotic cells,
higher PUMA and lower IL-6 expression levels.
Conclusion: Our results demonstrate a pathogenic role of TNF-mediated
up-regulation of iASPP and induction of SFs apoptosis by dissociating the iASPP
binding with transcription factor p73 in the rheumatoid joint, implicating iASPP as a
potential therapeutic target molecule in RA patients.
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Grant support: This work is supported by the grant 103-2314-B-006-058-MY3 from
Ministry of Science and Technology.
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