The C-Terminal Domain of Chondroadherin: A New Regulator of Osteoclast Motility Counteracting Bone Loss

Abstract

Chondroadherin (CHAD) is a leucine-rich protein promoting cell attachment through binding to integrin a 2 b 1 and syndecans. We observed that CHAD mRNA and protein were lower in bone biopsies of 50-year-old to 65-year-old osteoporotic women and in bone samples of ovariectomized mice versus gender/age-matched controls, suggesting a role in bone metabolism. By the means of an internal cyclic peptide (cyclicCHAD), we observed that its integrin binding sequence impaired preosteoclast migration through a nitric oxide synthase 2-dependent mechanism, decreasing osteoclastogenesis and bone resorption in a concentration-dependent fashion, whereas it had no effect on osteoblasts. Consistently, cyclicCHAD reduced transcription of two nitric oxide downstream genes, migfilin and vasp, involved in cell motility. Furthermore, the nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine, stimulated preosteoclast migration and prevented the inhibitory effect of cyclicCHAD. Conversely, the nitric oxide synthase 2 (NOS2) inhibitor, N5-(1-iminoethyl)-l-ornithine, decreased both preosteoclast migration and differentiation, confirming a role of the nitric oxide pathway in the mechanism of action triggered by cyclicCHAD. In vivo, administration of cyclicCHAD was well tolerated and increased bone volume in healthy mice, with no adverse effect. In ovariectomized mice cyclicCHAD improved bone mass by both a preventive and a curative treatment protocol, with an effect in line with that of the bisphosphonate alendronate, that was mimicked by the NOS2 inhibitor [L-N6-(1-Iminoethyl)-lysine.2 dihydrochloride]. In both mouse models, cyclicCHAD reduced osteoclast and bone resorption without affecting osteoblast parameters and bone formation. In conclusion, CHAD is a novel regulator of bone metabolism that, through its integrin binding domain, inhibits preosteoclast motility and bone resorption, with a potential translational impact for the treatment of osteoporosis.

Human adipose stem cells induced to osteogenic differentiation by an innovative collagen/hydroxylapatite hybrid scaffold

“…The genes ALP, ON, CHAD, SP7, and Sox9 had a higher expression with respect to cells t h a tw e r eg r o w no nt h ep l a s t i cv e s s e l( T C P S )a td3 postseeding. Cells that were grown on scaffold displayed higher expression levels of mRNAs of ALP, CHAD, SP7,andSOX9 genes than did those that were grown in the presence of OM at d 3 postseeding (29)(30)(31)(32)(33). Three genes-OCN, CHAD,andSox9-had a higher expression with respect to cells that were grownontheplasticvessel(TCPS),witha2-2.5 log 2 fold increase at d 9 postseeding.…”

“…4A). Of interest, the scaffold induced osteogenic gene markers, such as ALP, CHAD, ON, and transcription factors SP7 and SOX9 with respect to control at d 3 (29)(30)(31)(32)(33). The biomaterial continued to produce its osteogenic effect at d 9.…”

Crystal structure of human chondroadherin: solving a difficult molecular-replacement problem usingde novomodels

“…The structural information on the C-terminal domain presented here can now be used to improve existing therapeutic peptides. For example, the cyclic peptide 306-326 investigated by Capulli et al (2014) is based on the idea that the peptide will cyclize through the originally proposed disulfide-bonding pattern Cys306-Cys326 (Neame et al, 1994), whereas the true disulfide is between Cys304 and Cys326. Cys306 is 14 Å from Cys326, which may distort the peptide conformation in solution.…”

Genistein and menaquinone-4 treatment-induced alterations in the expression of mRNAs and their products are beneficial to osteoblastic MC3T3-E1 cell functions

“…Significant increases in the mRNA level of CHAD by MK-4 treatment were not consistently observed within 48 h, whereas strong expression of its protein was clearly visible by immunocytochemistry. CHAD has been reported to reduce preosteoclast motility and bone resorption without affecting osteoblast parameters, including the expression of runt related transcription factor 2 and BGLAP, the activity of ALP and bone formation (30). Therefore, the findings of the current study indicated a beneficial effect on bone formation in response to genistein + MK-4 treatment.…”