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Y Lai,
X-P Yu,
Y Zhang,
Q Tian,
H Song,
M T Mucignat,
R Perris,
J Samuels,
S Krasnokutsky,
M Attur,
J D Greenberg,
S B Abramson,
P E Di Cesare,
C J Liu
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ABSTRACT: The study aimed determining whether assessment of cartilage oligomeric matrix protein (COMP) degradation products could serve as a serological disease course and therapeutic response predictor in arthritis.
We generated a panel of monoclonal antibodies against COMP fragments and developed a novel capture enzyme-linked immunosorbent assay (ELISA) for detecting COMP fragments in patients with osteoarthritis (OA) and rheumatoid arthritis (RA). This test was also used to monitor COMP fragments in surgically-induced OA, collagen-induced arthritis (CIA), and tumor necrosis factor (TNF) transgenic animal models.
Compared with a commercial COMP ELISA kit that detected no significant difference in COMP levels between OA and control groups, a significant increase of the COMP fragments were noted in the serum of OA patients assayed by this newly established ELISA. In addition, serum COMP fragment levels were well correlated with severity in OA patients and the progression of surgically-induced OA in murine models. Furthermore, the serum levels of COMP fragments in RA patients, mice with CIA, and TNF transgenic mice were significantly higher when compared with their controls. Interestingly, treatment with TNFα inhibitors and methotrexate led to a significant decrease of serum COMP fragments in RA patients. Additionally, administration of Atsttrin [Tang, et al., Science 2011;332(6028):478] also resulted in a significant reduction in COMP fragments in arthritis mice models.
A novel sandwich ELISA is capable of reproducibly measuring serum COMP fragments in both arthritic patients and rodent arthritis models. This test also provides a valuable means to utilize serum COMP fragments for monitoring the effects of interventions in arthritis.
Osteoarthritis and Cartilage 05/2012; 20(8):854-62. · 3.90 Impact Factor
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ABSTRACT: Granulin-epithelin precursor (GEP) is an autocrine growth factor that has been implicated in embryonic development, tissue repair, tumorigenesis, and inflammation. Here we report that GEP was expressed in skeletal muscle tissue and its level was differentially altered in the course of C2C12 myoblast fusion. The GEP expression during myoblast fusion was a consequence of MyoD transcription factor binding to several E-box (CANNTG) sequences in the 5'-flanking regulatory region of GEP gene, followed by transcription. Recombinant GEP potently inhibited myotube formation from C2C12 myoblasts whereas the knockdown of endogenous of GEP via a siRNA approach accelerated the fusion of myoblasts to myotubes. Interestingly, the muscle fibers of GEP knockdown mice were larger in number but noticeably smaller in size when compared to the wild-type. Mechanistic studies revealed that during myoblast fusion, the addition of GEP led to remarkable reductions in the expressions of muscle-specific transcription factors, including MyoD. In addition, the regulation of myotube formation by GEP is mediated by the anti-myogenic factor JunB, which is upregulated following GEP stimulation. Thus, GEP growth factor, JunB, and MyoD transcription factor form a regulatory loop and act in concert in the course of myogenesis.
Cellular and Molecular Life Sciences CMLS 12/2011; 69(11):1855-73. · 6.57 Impact Factor
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Wei Tang,
Yi Lu,
Qing-Yun Tian,
Yan Zhang,
Feng-Jin Guo,
Guang-Yi Liu,
Nabeel Muzaffar Syed, Yongjie Lai,
Edward Alan Lin,
Li Kong, [......],
Ai-Hao Ding,
Alexandra Zanin-Zhorov,
Michael L Dustin,
Jian Tao,
Joseph Craft,
Zhinan Yin,
Jian Q Feng,
Steven B Abramson,
Xiu-Ping Yu,
Chuan-ju Liu
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ABSTRACT: The growth factor progranulin (PGRN) has been implicated in embryonic development, tissue repair, tumorigenesis, and inflammation, but its receptors remain unidentified. We report that PGRN bound directly to tumor necrosis factor receptors (TNFRs) and disturbed the TNFα-TNFR interaction. PGRN-deficient mice were susceptible to collagen-induced arthritis, and administration of PGRN reversed inflammatory arthritis. Atsttrin, an engineered protein composed of three PGRN fragments, exhibited selective TNFR binding. PGRN and Atsttrin prevented inflammation in multiple arthritis mouse models and inhibited TNFα-activated intracellular signaling. Collectively, these findings demonstrate that PGRN is a ligand of TNFR, an antagonist of TNFα signaling, and plays a critical role in the pathogenesis of inflammatory arthritis in mice. They also suggest new potential therapeutic interventions for various TNFα-mediated pathologies and conditions, including rheumatoid arthritis.
Science 03/2011; 332(6028):478-84. · 31.20 Impact Factor
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ABSTRACT: To determine 1) whether a protein interaction network exists between granulin-epithelin precursor (GEP), ADAMTS-7/ADAMTS-12, and cartilage oligomeric matrix protein (COMP); 2) whether GEP interferes with the interactions between ADAMTS-7/ADAMTS-12 metalloproteinases and COMP substrate, including the cleavage of COMP; 3) whether GEP affects tumor necrosis factor alpha (TNFalpha)-mediated induction of ADAMTS-7/ADAMTS-12 expression and COMP degradation; and 4) whether GEP levels are altered during the progression of arthritis.
Yeast two-hybrid, in vitro glutathione S-transferase pull-down, and coimmunoprecipitation assays were used to 1) examine the interactions between GEP, ADAMTS-7/ADAMTS-12, and COMP, and 2) map the binding sites required for the interactions between GEP and ADAMTS-7/ADAMTS-12. Immunofluorescence cell staining was performed to visualize the subcellular localization of GEP and ADAMTS-7/ADAMTS-12. An in vitro digestion assay was employed to determine whether GEP inhibits ADAMTS-7/ADAMTS-12-mediated digestion of COMP. The role of GEP in inhibiting TNFalpha-induced ADAMTS-7/ADAMTS-12 expression and COMP degradation in cartilage explants was also analyzed.
GEP bound directly to ADAMTS-7 and ADAMTS-12 in vitro and in chondrocytes, and the 4 C-terminal thrombospondin motifs of ADAMTS-7/ADAMTS-12 and each granulin unit of GEP mediated their interactions. Additionally, GEP colocalized with ADAMTS-7 and ADAMTS-12 on the cell surface of chondrocytes. More importantly, GEP inhibited COMP degradation by ADAMTS-7/ADAMTS-12 in a dose-dependent manner through 1) competitive inhibition through direct protein-protein interactions with ADAMTS-7/ADAMTS-12 and COMP, and 2) inhibition of TNFalpha-induced ADAMTS-7/ADAMTS-12 expression. Furthermore, GEP levels were significantly elevated in patients with either osteoarthritis or rheumatoid arthritis.
Our observations demonstrate a novel protein-protein interaction network between GEP, ADAMTS-7/ADAMTS-12, and COMP. Furthermore, GEP is a novel specific inhibitor of ADAMTS-7/ADAMTS-12-mediated COMP degradation and may play a significant role in preventing the destruction of joint cartilage in arthritis.
Arthritis & Rheumatism 07/2010; 62(7):2023-36. · 7.87 Impact Factor
