CCN3 increases BMP‐4 expression and bone mineralization in osteoblasts

Abstract

The nephroblastoma overexpressed (NOV) gene, also called CCN3, regulates differentiation of skeletal mesenchymal cells. Bone morphogenetic proteins (BMPs) play important roles in osteoblast differentiation and bone formation, but the effects of CCN3 on BMP expression and bone formation in cultured osteoblasts are largely unknown. Here we found that CCN3 increased BMP-4 expression and bone nodule formation in cultured osteoblast. Monoclonal antibodies for α5β1 and αvβ5 integrins, and inhibitors of integrin-linked kinase (ILK), p38, and JNK, all inhibited CCN3-induced bone nodule formation and BMP-4 up-regulation of osteoblasts. CCN3 stimulation increased the kinase activity of ILK and phosphorylation of p38 and JNK. Inhibitors of activator protein-1 (AP-1) also suppressed bone nodule formation and BMP-4 expression enhanced by CCN3. Moreover, CCN3-induced c-Jun translocation into the nucleus, and the binding of c-Jun to the AP-1 element on the BMP-4 promoter were both inhibited by specific inhibitors of the ILK, p38, and JNK cascades. Taken together, our results provide evidence that CCN3 enhances BMP-4 expression and bone nodule formation in osteoblasts, and that the integrin receptor, ILK, p38, JNK, and AP-1 signaling pathways may be involved.

WNT1-induced Secreted Protein-1 (WISP1), a Novel Regulator of Bone Turnover and Wnt Signaling

“…A more recent report confirms the notion that CCN3 is an inhibitory factor in bone regeneration (21). A previous study claims that CCN3 increases BMP-2/4 and subsequent mineralization (22). The reasons for these discrepant results are not clear but could be due to the fact that the latter study applied CCN3 protein externally to the cultures, whereas the former ones used adenovirus infection to overexpress CCN2 from inside the cell.…”

“…Thus, CCN3 may have functions potentially dependent on its levels of expression (over or under) with possible variability from where in the cell it is introduced. Studies performed in vitro indicate that the influence of CCN3 on osteoblast differentiation depends on functional Notch signaling (19) and integrin receptors, as well as ILK, p38, JNK, and AP-1 pathways (22).…”

Reduced NOV expression correlates with disease progression in colorectal cancer and is associated with survival, invasion and chemoresistance of cancer cells

“…For example, JNK pathway has been shown to mediate NOV-induced CCL2 expression in rat brain astrocytes [20]. NOV enhances bone morphogenetic protein-4 expression and bone nodule formation in osteoblasts, via integrin-linked kinase, p38, JNK, and AP-1 signalling pathways [21]. Following an initial assessment of signal transduction through MAPK pathways using a Kinex TM antibody microarray (Supplementary Figure 4), changes were observed in phosphorylation of ERK1/2 and JNK, but not p38, in the RKO NOVkd and HT115 NOVexp cells.…”

“…For example, NOV promoted CCL2 production by Rho/ROCK/JNK/NF-κB pathway in rat brain astrocytes, and played a role in neuro-inflammation [20]. NOV was also able to promote bone formation by up-regulating BMP-4 expression in osteoblasts through integrin-linked kinase, p38, JNK, and AP-1 signalling pathways [21]. To assess the involvement of JNK in the NOV-induced effect on CRC, we determined the activation of JNK in the NOV knockdown and overexpression cells.…”

Stromal Senp1 promotes mouse early folliculogenesis by regulating BMP4 expression

“…Similar to SOX2, OCT3/4 are also regulated by SUMOylation [34]. The BMP4 gene promoter also contains an AP-1 element therefore BMP4 expression can be regulated by transcriptional factor AP-1, and the integrin receptor, ILK, p38, and JNK signaling pathways [35]. It is well documented that AP-1 and upstream signaling are regulated by SUMOylation.…”