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Evaluation of Keratinocyte Proliferation on Two- and Three-dimensional Type I Collagen Substrates
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Inhibition of connective tissue growth factor/CCN2 expression in human dermal fibroblasts by interleukin-1alpha and

D Nowinski1, A Koskela, E Kiwanuka

  • 1Department of Surgical Sciences, Plastic Surgery Unit, Uppsala University, Uppsala, Sweden. daniel.nowinski@akademiska.se

Journal of Cellular Biochemistry
|June 15, 2010
PubMed

Insights

Interleukin-1 (IL-1) alpha and beta suppress connective tissue growth factor (CTGF) production, revealing a new mechanism for regulating fibrotic processes in skin.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Dermatology

Background:

  • Connective tissue growth factor (CTGF/CCN2) is a key protein in tissue repair and is overexpressed in fibrotic conditions.
  • Transforming growth factor-beta (TGF-beta) induces CTGF expression.
  • Keratinocytes can downregulate TGF-beta-induced CTGF in fibroblasts via Interleukin-1 alpha (IL-1 alpha).

Purpose of the Study:

  • To investigate the mechanisms by which IL-1 alpha and IL-1 beta downregulate CTGF expression.
  • To explore the role of Smad signaling and TGF-beta activated kinase 1 (TAK1) in IL-1 mediated CTGF suppression.

Main Methods:

  • Human dermal fibroblasts and NIH 3T3 cells were treated with IL-1 alpha or IL-1 beta in the presence or absence of TGF-beta1.
  • CTGF mRNA and protein expression levels were measured.
  • CTGF promoter activity and Smad 3-binding CAGA element activity were assessed.
  • Smad 3 phosphorylation and Smad 7 mRNA expression were analyzed.
  • RNA interference was used to investigate the role of TAK1.

Main Results:

  • IL-1 alpha and IL-1 beta suppressed both basal and TGF-beta-induced CTGF mRNA and protein expression.
  • IL-1 inhibited TGF-beta-stimulated CTGF promoter activity and Smad 3-binding CAGA element activity.
  • IL-1 treatment led to decreased Smad 3 phosphorylation and increased Smad 7 mRNA expression.
  • TAK1 was identified as necessary for IL-1's inhibition of TGF-beta-stimulated CTGF expression.

Conclusions:

  • IL-1 alpha and IL-1 beta effectively suppress CTGF expression in fibroblasts through mechanisms involving Smad signaling and TAK1.
  • These findings enhance the understanding of CTGF regulation in dermal fibroblasts.
  • The results may have implications for understanding and treating fibrotic skin conditions.

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