scholarly journals Skeletal Overexpression of Connective Tissue Growth Factor Impairs Bone Formation and Causes Osteopenia

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4374-4381 ◽  
Author(s):  
Anna Smerdel-Ramoya ◽  
Stefano Zanotti ◽  
Lisa Stadmeyer ◽  
Deena Durant ◽  
Ernesto Canalis

Connective tissue growth factor (CTGF), a member of the CCN family of proteins, is expressed in skeletal cells, and the ctgf null mutation leads to neonatal lethality due to defects in skeletal development. To define the function of CTGF in the postnatal skeleton, we created transgenic mice overexpressing CTGF under the control of the human osteocalcin promoter. CTGF transgenic female and male mice exhibited a significant decrease in bone mineral density, compared with wild-type littermate controls. Bone histomorphometry revealed that CTGF overexpression caused decreased trabecular bone volume due to impaired osteoblastic activity because mineral apposition and bone formation rates were decreased. Osteoblast and osteoclast number and bone resorption were not altered. Calvarial osteoblasts and stromal cells from CTGF transgenics displayed decreased alkaline phosphatase and osteocalcin mRNA levels and reduced bone morphogenetic protein (BMP) signaling mothers against decapentaplegic, Wnt/β-catenin, and IGF-I/Akt signaling. In conclusion, CTGF overexpression in vivo causes osteopenia, secondary to decreased bone formation, possibly by antagonizing BMP, Wnt, and IGF-I signaling and activity.

Vascular ◽  
2013 ◽  
Vol 22 (1) ◽  
pp. 20-27 ◽  
Author(s):  
YH Meng ◽  
C Tian ◽  
L Liu ◽  
L Wang ◽  
Q Chang

Little is known about the molecular mechanisms of ascending thoracic aortic aneurysms (ATAAs). Abnormal extracellular matrix changes and variations of vascular smooth muscle cells (VSMCs) have been implicated in abdominal aortic aneurysm formation. Our objective was to investigate the alterations of collagen, stimulators of collagen synthesis and synthetic VSMCs in patients with ATAA. Surgical samples from ATAA were taken from 20 patients, and 18 control aortas were obtained during coronary artery bypass surgery. All aortic wall specimens were fixed for histology and immunohistochemistry for collagen, connective tissue growth factor (CTGF) and osteopontin. Realtime polymerase chain reaction was used to determine their mRNA expression. Histology and semi-quantitative analysis demonstrated that protein levels of collagen, CTGF and osteopontin significantly increased by 1.9-, 1.4- and 2.2-fold, respectively ( P < 0.01 for all) in the ATAA group than in the control group. Similar results were shown in mRNA levels of type Iα1and IIIα1 collagen, CTGF and osteopontin. The protein levels of CTGF and osteopontin were positively correlated with aortic diameter ( r = 0.67, r = 0.73; P < 0.01 for both). In conclusion, overexpression of aortic CTGF and synthetic VSMCs marker (osteopontin), which is likely to be responsible for elevated aortic collagen content, may provide a potential mechanism for aneurysmal enlargement.


Diabetes ◽  
2003 ◽  
Vol 52 (12) ◽  
pp. 2975-2983 ◽  
Author(s):  
S. Lam ◽  
R. N. van der Geest ◽  
N. A.M. Verhagen ◽  
F. A. van Nieuwenhoven ◽  
I. E. Blom ◽  
...  

2009 ◽  
Vol 420 (3) ◽  
pp. 413-420 ◽  
Author(s):  
Eriko Aoyama ◽  
Takako Hattori ◽  
Mitsuhiro Hoshijima ◽  
Daisuke Araki ◽  
Takashi Nishida ◽  
...  

CCN2/CTGF (CCN family 2/connective tissue growth factor) is a multi-cellular protein with a broad range of activities. It modulates many cellular functions, including proliferation, migration, adhesion and extracellular matrix production, and it is thus involved in many biological and pathological processes. In particular, CCN2/CTGF is essential for normal skeletal development. To identify CCN2/CTGF-interactive proteins capable of modulating its action in cartilage, we carried out a yeast two-hybrid screening using CCN2/CTGF peptide as a bait and a cDNA library from a chondrocytic cell line, HCS-2/8. In the present paper, we report the identification of aggrecan, which is a major proteoglycan of the extracellular matrix in cartilage, as a CCN2/CTGF-binding protein. Among the four domains of CCN2/CTGF, the IGFBP [IGF (insulin-like growth factor)-binding protein-like] and/or VWC (von Willebrand factor type C) domains had a direct interaction with aggrecan in a yeast two-hybrid assay. The results of a solid-phase-binding assay using aggrecan-coated plates also showed binding to recombinant CCN2/CTGF in a dose-dependent manner. rIGFBP (recombinant IGFBP) and rVWC (recombinant VWC) module peptides had stronger binding to aggrecan compared with rTSP1 (recombinant thrombospondin type 1 repeat) and rCT (recombinant C-terminal cystine knot) module peptides. SPR (surface plasmon resonance) analysis showed the direct interaction between the CCN2/CTGF and aggrecan, and ectopically overexpressed CCN2/CTGF and AgG3 (G3 domain of aggrecan) confirmed their binding In vivo. Indirect immunofluorescence analysis indicated that CCN2/CTGF was extracellularly co-localized with aggrecan on HCS-2/8 cells. The rIGFBP–rVWC peptide effectively enhanced the production and release of aggrecan compared with the rTSP–rCT peptide in chondrocytes. These results indicate that CCN2/CTGF binds to aggrecan through its N-terminal IGFBP and VWC modules, and this binding may be related to the CCN2/CTGF-enhanced production and secretion of aggrecan by chondrocytes.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2593-2593
Author(s):  
Hongbo Lu ◽  
Venkata Lokesh Battula ◽  
Yuexi Shi ◽  
Richard B Lock ◽  
Suzanne Spong ◽  
...  

Abstract Abstract 2593 Connective tissue growth factor (CTGF/CCN2) is a member of the CCN family of proteins involved in extracellular matrix production, tumor cell proliferation, adhesion, migration, and metastasis. Recent studies have shown that CTGF expression is elevated in 75% of acute lymphoblastic leukemia (Br J Haematol, 2007; 138(6):740–8), and that increased expression of CTGF is associated with inferior outcome in B-ALL (Blood, 2007; 109(7):3080–3). In this study, we characterized the functional role and downstream signaling pathways of CTGF in ALL cells. First, we utilized lentiviral shRNA to knock-down CTGF in RS4;11 and REH ALL cells expressing high levels of CTGF mRNA (479.3±37.2 and 57.3±5.9 copies per 100 copies of ABL1, respectively). Silencing of CTGF (CTGF-knockdown, CTGF-kd) resulted in significant suppression of leukemia cell growth (57% in RS4;11 and by 70% in REH) compared to control vector. CTGF knockdown moderately reduced adhesion of RS4;11 to fibronectin (27%±0.1%). In the in vitro culture system, CTGF knockdown significantly enhanced growth inhibition and apoptosis induction after 48 hour exposure to chemotherapy agents (annexinV(+): Vincristine 25.8±3.5%, Vincristine/CTGF-kd 42.6±2.8%; Dexamethasone 66.3±1.8%, Dexamethasone/CTGF-kd 99.3±0.6%; Methotrexate, 17.4±0.6%, Methotrexate/CTGF-kd 39.5±3.9). Analysis of signaling pathways showed that CTGF down-regulation inhibits Src phosphorylation at Tyr416. Remarkably, phosphorylation of AKT at Ser473, and of mTOR downstream targets S6 Ribosomal Protein and 4E-BP1 were significantly inhibited in CTGF-knockdown RS4;11 cells, concomitantly with upregulation of expression of AKT targets Bim and p27. No changes in the levels of apoptotic regulators cIAP1 and Bcl-xL were found. This data suggest that CTGF regulates growth and chemosensitivity of ALL cells through Src and AKT/mTOR signaling. We previously reported that an anti-CTGF monoclonal antibody significantly extended median survival of mice implanted with xenografts derived from a primary CTGF expressing ALL sample in NOD/SCID mice. We are now investigating the effects of combining anti-CTGF treatment with cytotoxic chemotherapy in this model. Blocking CTGF signaling may represent a useful adjunct to cytotoxic therapies in acute lymphoblastic leukemia. Disclosures: Spong: Fibrogen: Employment, Equity Ownership.


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