Nov(CCN3)

LSJL upregulates Nov(CCN3) over 3 fold.

CCN3 modulates bone turnover and is a novel regulator of skeletal metastasis.

"CCN3 impairs normal osteoblast differentiation through multiple mechanisms, which include the neutralization of pro-osteoblastogenic stimuli such as BMP and Wnt family signals or the activation of pathways that suppress osteoblastogenesis, such as Notch. In contrast, CCN3 is known to promote chondrocyte differentiation. Given these functions, it is not surprising that CCN3 has been implicated in the progression of primary bone cancers such as osteosarcoma, Ewing's sarcoma and chondrosarcoma."

"With one exception, all CCN family members possess an N-terminal signal peptide (SP) followed by four modular domains with homology to an insulin-like growth factor binding protein (IGFBP) domain, a von Willebrand factor type C domain (VWC), a Thrombospondin-1 type repeat (TSP-1) and a C-terminal region (CT) containing a cysteine knot structure. CCN5 is the only family member that deviates from this overall domain organization due to the absence of the CT domain"

"CCN3 plays a significant role in suppressing osteoblast differentiation and, at high concentrations, may enhance osteoclast differentiation or function."

"CCN3 was also shown to augment the release of the Notch Intracellular Domain (NICD) from full length Notch, leading to an increase in Hairy/Enhancer of Split (HES){Hes1 is upregulated in LSJL} and Hairy/Enhancer of Split with YRPW motif 1 (HEY) transcription and ultimately to impaired osteoblast differentiation"

"CCN3 can function to blunt BMP2 action by directly binding and neutralizing BMP2 or through indirect mechanisms that involve stabilization of BMP2 antagonists."

"CCN3 [can favor] osteoblast differentiation and bone mineralization by inducing the expression of BMP-4, a potent inducer of osteoblast differentiation. These CCN3-mediated effects were dependent on α5β1 and αvβ5 integrin receptors and subsequent activation of Integrin Linked Kinase (ILK), p38 and c-Jun Kinase (JNK). Interestingly, the concentrations of CCN3 (3–30 ng/ml) that induced osteoblast differentiation were much lower when compared to CCN3 concentrations (300–600 ng/mL) that blocked osteoblast differentiation"

"MMP9 [triggers] the switch between the stationary and migratory state by altering cytoskeleton rearrangement through activation of RhoA/Paxillin/β-catenin signaling"

"CCN3 is a positive regulator of chondrocyte differentiation through the induction of TGF-β2, which is important during the condensation stage of chondrocyte differentiation. Moreover, TGF-β1 functions to impair chondrocyte differentiation[this is inconsistent with previous findings], and has been shown to diminish CCN3 levels"


Novel effects of CCN3 that may direct the differentiation of chondrocytes.

"we found CCN family protein 3 (CCN3) was abundantly produced in rat developing epiphyseal cartilage. Evaluations in vitro showed that CCN3 repressed epiphyseal chondrocyte proliferation, while promoting matrix production in multiple assays performed. Furthermore, CCN3 enhanced the articular chondrocytic phenotype; whereas it repressed the one representing endochondral ossification. Additionally, the phenotype of growth plate chondrocytes and chondrogenic progenitors also appeared to be affected by CCN3 in a similar manner."

"One of the distinct characteristics of articular chondrocytes in vivo is less proliferative activity than that of growth-plate chondrocytes, which are forced to proliferate."

"the differentiation of mouse costal chondrocytes was repressed by rCCN3. However, and surprisingly, rCCN3 promoted proteoglycan synthesis by the epiphyseal chondrocytes. When estimated by [35S] sulfate incorporation, enhanced proteoglycan synthesis was observed as short as 22 h after the addition of rCCN3 at 2 nM"

"the number of cells producing tenascin-C, which was a typical marker of articular chondrocytes, was strikingly higher in the epiphyseal chondrocytes [when exposed to exogenous CCN3]"

"CCN3 can direct developing chondrocytes to differentiate towards non-calcifying articular chondrocytes."

"External factors, such as mechanical overload to the articular cartilage, could turn CCN3 off, inducing chondrocytes to enter the endochondral ossification pathway to form osteophytes"


Roles of heterotypic CCN2/CTGF-CCN3/NOV and homotypic CCN2-CCN2 interactions in expression of the differentiated phenotype of chondrocytes.

"We present evidence that CCN2-CCN3 interactions modulated CCN2 activity such as enhancement of ACAN and col2a1 expression. Curiously, CCN2 enhanced, whereas CCN3 inhibited, the expression of aggrecan and col2a1 mRNA in HCS-2/8 cells, and combined treatment with CCN2 and CCN3 abolished the inhibitory effect of CCN3. These effects were neutralized with an antibody against the von Willebrand factor type C domain of CCN2 (11H3). This antibody diminished the binding between CCN2 and CCN2, but enhanced that between CCN3 and CCN2. Our results suggest that CCN2 could form homotypic and heterotypic dimers with CCN2 and CCN3, respectively. Strengthening the binding between CCN2 and CCN3 with the 11H3 antibody had an enhancing effect on aggrecan expression in chondrocytes, suggesting that CCN2 had an antagonizing effect by binding to CCN3."

So maybe CTGF can help enhance LSJL results.

"In CCN2 null mutant mice, bone formation is inhibited owing to impairment of both chondrogenesis and growth plate angiogenesis"

"The CT domain of CCN2 interacts directly with fibronectin and enhances cell adhesion of chondrocytes through binding to integrin α5β1. This domain also binds to integrin α5β1 to promote adhesion and migration of pancreatic stellate cells"

"CCN2 directly binds to bone morphogenetic protein (BMP)-4 and transforming growth factor-β (TGF-β) through its VWC module, and prevents or enhances their binding to their own receptors. Moreover, CCN2 binds vascular endothelial growth factor and inhibits its angiogenic effect"

"CCN2 dose-dependently increased ACAN and col2a1 expression, which was downregulated by CCN3."