@article{867ea284349a4edd8c77e8c8f35e0241,
title = "The regenerative effects of CCN2 independent modules on chondrocytes in vitro and osteoarthritis models in vivo",
abstract = "The role of CCN family proteins has been proven to be of extreme importance in the process of cartilage development and endochondral ossification. The second member, CCN2, consists of 4 conserved modules that interact with a number of cofactors to display multiple functions. Although the potentially therapeutic effect of intact CCN2 on cartilage regeneration has been indicated by a number of studies, the regenerative effect of independent modules comprising CCN2 has never been evaluated before. This study aims to discover a more robust and effective CCN2 derivative to induce regeneration through assessing the effect of CCN2 independent modules on regeneration in vitro and in vivo, in comparison to the full length CCN2. In vitro evaluation using human chondrocytic cells showed a remarkable enhancing effect of several single modules on the gene expression of cartilaginous extracellular matrix components; whereas combinations of 2 or 3 modules rather diminished such effects. Interestingly, combination of all 4 modules redeemed the effect of intact CCN2 in vitro. Suspecting the re-assembly of the 4 modules, interaction among the modules was examined by surface plasmon resonance analysis. However, the results did not support the possible formation of a tetramodular complex. Next, the thrombospondin 1 type 1 repeat module (TSP1), which was found most promising in the experiments in vitro, and the combination of 4 modules were forwarded further to in vivo confirmation using 2 rat osteoarthritis (OA) models. As a result, TSP1 displayed more prominent regenerative effects than intact CCN2 on damaged cartilage. Unexpectedly, the combination of 4 modules showed limited effects in vivo. These results indicate the utility of TSP1 in the regenerative therapeutics of OA. Possible molecular mechanism that enables conditional reconstruction of CCN2 by 4 modules is discussed as well.",
keywords = "CCN family, CCN2, IGFBP, Regeneration, TSP1",
author = "{Abd El Kader}, Tarek and Satoshi Kubota and Takashi Nishida and Takako Hattori and Eriko Aoyama and Danilo Janune and Hara, {Emilio S.} and Mitsuaki Ono and Yasuhiko Tabata and Takuo Kuboki and Masaharu Takigawa",
note = "Funding Information: The major purpose of the current study is to assess the regenerative effect of CCN2 independent modules on damaged cartilage, which is typically involved in OA, and finally to help find a CCN2 derivative more feasible as a therapeutic agent. We developed this study based on 2 hypotheses. The first hypothesis is based on the results obtained from our previous studies showing that CCN2 was capable of regenerating damaged cartilage, and that mitogen-activated kinases (MAPKs) could be activated by the independent modules of CCN2 [14] . However, the precise effects of independent modules on chondrocyte phenotype and their regenerative effects on damaged cartilage have never been investigated. Thus, suspecting positive effects of each module on chondrocytic phenotype, we conducted the present study and found more than expected. The data presented in this study clearly demonstrate that each of the CCN2 independent modules has a strong effect on the expression level of both the aggrecan and type II collagen in HCS-2/8. According to our previous study, IGFBP, TSP1 and CT modules alone are able to activate the c-jun N-terminal kinase (JNK) pathway [14] . Therefore, the effect of these modules on the chondrocyte marker genes is anticipated to be mediated by JNK. This notion is supported by the fact that intact CCN2 promotes both proliferation and differentiation of chondrocytes partly through this signaling pathway [27] . Regarding this matter another question is how these modules could initiate this signaling. It is known that CCN family members contain multiple ligands for integrins, and a variety of biological effects of CCN family proteins are mediated by these adhesion receptors [10,11] . Therefore, interaction between integrins and the individual modules may ignite the intracellular signal transduction cascade by itself. Alternatively, these modules may exert the observed effects on HCS-2/8 cells via indirect manipulation of the extracellular signaling molecules, such as BMP-2. ",
year = "2014",
month = feb,
doi = "10.1016/j.bone.2013.11.010",
language = "English",
volume = "59",
pages = "180--188",
journal = "Bone",
issn = "8756-3282",
publisher = "Elsevier Inc.",
}
