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CCN5 attenuates profibrotic phenotypes of fibroblasts through the Smad6-CCN2 pathway: Potential role in epidural fibrosis.

Xu H, Liu C, Sun Z, Guo X, Zhang Y, Liu M, Li P - Int. J. Mol. Med. (2015)

Bottom Line: CCN5 upregulation also reduced an increase in collagen type I, α1 (COL1A1) and total collagen concentrations.Additionally, CCN5 over-expression decreased CCN2 expression and increased Smad6 phosphorylation.Mechanism analysis revealed that blocking Smad6 signaling significantly ameliorated the inhibitory effect of CCN5 on the CCN2 levels, accompanied by the reduction in cell proliferation and collagen production.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, The Third Affiliated Hospital (Shaanxi Provincial People's Hospital), Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.

ABSTRACT
Epidural fibrosis is characterized by the development of dense and thick scar tissue adjacent to the dural mater and ranked as the major contributor for post-operative pain recurrence after laminectomy or discectomy. Recently, CCN5 exhibited an inhibitory effect on connective tissue growth factor (CTGF)/CCN2 (a critical regulator for fibrotic disease)‑mediated fibrogenesis. However, its function in epidural fibrosis and the underlying mechanisms involved remain to be determined. In this study, an obvious downregulation of CCN5 was observed in scar tissues from laminectomized rats, concomitant with a marked upregulation of CCN2, suggesting a potential negative regulatory role of CCN5 in fibrogenesis. Furthermore, CCN5 overexpression notably mitigated transforming growth factor‑β1-enhanced fibroblast viability and proliferation. Of note, CCN5 upregulation inhibited the switch of fibroblasts into myofibroblasts as its overexpression abrogated the expression of the myofibroblast marker, α-smooth muscle actin (α-SMA). CCN5 upregulation also reduced an increase in collagen type I, α1 (COL1A1) and total collagen concentrations. Additionally, CCN5 over-expression decreased CCN2 expression and increased Smad6 phosphorylation. Mechanism analysis revealed that blocking Smad6 signaling significantly ameliorated the inhibitory effect of CCN5 on the CCN2 levels, accompanied by the reduction in cell proliferation and collagen production. These results confirm that CCN5 exerts an anti-fibrotic function by regulating the Smad6-CCN2 pathway, thereby indicating a potential approach for ameliorating epidural fibrosis after laminectomy.

No MeSH data available.


Related in: MedlinePlus

CCN5 functions in TGF-β1-induced proliferation and profibrotic phenotype through the Smad6-CCN2 pathway. To investigate the underlying mechanism, the effect of CCN5 on Smad6 signaling was determined (A). After silencing Smad6 levels by preconditioning with its specific siRNA, the expression levels of CCN2 were measured (B). The function of Smad6 in CCN5-triggered inhibitory effects on fibroblast proliferation (C) was ascertained by [3H]-TdR. The corresponding effect on collagen contents was also determined (D). *P<0.05.
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f6-ijmm-36-01-0123: CCN5 functions in TGF-β1-induced proliferation and profibrotic phenotype through the Smad6-CCN2 pathway. To investigate the underlying mechanism, the effect of CCN5 on Smad6 signaling was determined (A). After silencing Smad6 levels by preconditioning with its specific siRNA, the expression levels of CCN2 were measured (B). The function of Smad6 in CCN5-triggered inhibitory effects on fibroblast proliferation (C) was ascertained by [3H]-TdR. The corresponding effect on collagen contents was also determined (D). *P<0.05.

Mentions: To clarify the underlying mechanisms involved in the CCN5-induced anti-fibrotic function, we investigated Smad6 signaling due to the critical role it plays in blocking TGF-β1-triggered other Smad signaling (20,21). As shown in Fig. 6A, the elevated CCN5 expression markedly increased the phosphorylation levels of Smad6. When CCN5 expression was upregulated, CCN2 protein levels induced by TGF-β1 were markedly inhibited. However, silencing Smad6 signaling obviously ameliorated this inhibitory effect on CCN2 levels, suggesting that CCN5 was able to abrogate TGF-β1-induced CCN2 expression levels by Smad6 signaling (Fig. 6B). Furthermore, the Smad6 pathway was blocked with its specific siRNA, and cell proliferation was markedly increased in the CCN5 and TGF-β1-treated groups compared with the control group (Fig. 6C). Of note, the inhibitory function of CCN5 on collagen production was notably decreased (Fig. 6D). These results suggested that the Smad6-CCN2 pathway was involved in the anti-fibrotic function of CCN5.


CCN5 attenuates profibrotic phenotypes of fibroblasts through the Smad6-CCN2 pathway: Potential role in epidural fibrosis.

Xu H, Liu C, Sun Z, Guo X, Zhang Y, Liu M, Li P - Int. J. Mol. Med. (2015)

CCN5 functions in TGF-β1-induced proliferation and profibrotic phenotype through the Smad6-CCN2 pathway. To investigate the underlying mechanism, the effect of CCN5 on Smad6 signaling was determined (A). After silencing Smad6 levels by preconditioning with its specific siRNA, the expression levels of CCN2 were measured (B). The function of Smad6 in CCN5-triggered inhibitory effects on fibroblast proliferation (C) was ascertained by [3H]-TdR. The corresponding effect on collagen contents was also determined (D). *P<0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494601&req=5

f6-ijmm-36-01-0123: CCN5 functions in TGF-β1-induced proliferation and profibrotic phenotype through the Smad6-CCN2 pathway. To investigate the underlying mechanism, the effect of CCN5 on Smad6 signaling was determined (A). After silencing Smad6 levels by preconditioning with its specific siRNA, the expression levels of CCN2 were measured (B). The function of Smad6 in CCN5-triggered inhibitory effects on fibroblast proliferation (C) was ascertained by [3H]-TdR. The corresponding effect on collagen contents was also determined (D). *P<0.05.
Mentions: To clarify the underlying mechanisms involved in the CCN5-induced anti-fibrotic function, we investigated Smad6 signaling due to the critical role it plays in blocking TGF-β1-triggered other Smad signaling (20,21). As shown in Fig. 6A, the elevated CCN5 expression markedly increased the phosphorylation levels of Smad6. When CCN5 expression was upregulated, CCN2 protein levels induced by TGF-β1 were markedly inhibited. However, silencing Smad6 signaling obviously ameliorated this inhibitory effect on CCN2 levels, suggesting that CCN5 was able to abrogate TGF-β1-induced CCN2 expression levels by Smad6 signaling (Fig. 6B). Furthermore, the Smad6 pathway was blocked with its specific siRNA, and cell proliferation was markedly increased in the CCN5 and TGF-β1-treated groups compared with the control group (Fig. 6C). Of note, the inhibitory function of CCN5 on collagen production was notably decreased (Fig. 6D). These results suggested that the Smad6-CCN2 pathway was involved in the anti-fibrotic function of CCN5.

Bottom Line: CCN5 upregulation also reduced an increase in collagen type I, α1 (COL1A1) and total collagen concentrations.Additionally, CCN5 over-expression decreased CCN2 expression and increased Smad6 phosphorylation.Mechanism analysis revealed that blocking Smad6 signaling significantly ameliorated the inhibitory effect of CCN5 on the CCN2 levels, accompanied by the reduction in cell proliferation and collagen production.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, The Third Affiliated Hospital (Shaanxi Provincial People's Hospital), Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.

ABSTRACT
Epidural fibrosis is characterized by the development of dense and thick scar tissue adjacent to the dural mater and ranked as the major contributor for post-operative pain recurrence after laminectomy or discectomy. Recently, CCN5 exhibited an inhibitory effect on connective tissue growth factor (CTGF)/CCN2 (a critical regulator for fibrotic disease)‑mediated fibrogenesis. However, its function in epidural fibrosis and the underlying mechanisms involved remain to be determined. In this study, an obvious downregulation of CCN5 was observed in scar tissues from laminectomized rats, concomitant with a marked upregulation of CCN2, suggesting a potential negative regulatory role of CCN5 in fibrogenesis. Furthermore, CCN5 overexpression notably mitigated transforming growth factor‑β1-enhanced fibroblast viability and proliferation. Of note, CCN5 upregulation inhibited the switch of fibroblasts into myofibroblasts as its overexpression abrogated the expression of the myofibroblast marker, α-smooth muscle actin (α-SMA). CCN5 upregulation also reduced an increase in collagen type I, α1 (COL1A1) and total collagen concentrations. Additionally, CCN5 over-expression decreased CCN2 expression and increased Smad6 phosphorylation. Mechanism analysis revealed that blocking Smad6 signaling significantly ameliorated the inhibitory effect of CCN5 on the CCN2 levels, accompanied by the reduction in cell proliferation and collagen production. These results confirm that CCN5 exerts an anti-fibrotic function by regulating the Smad6-CCN2 pathway, thereby indicating a potential approach for ameliorating epidural fibrosis after laminectomy.

No MeSH data available.


Related in: MedlinePlus