Involvement of p300 in TGF-beta/Smad-pathway-mediated alpha2(I) Collagen Expression in Mouse Mesangial Cells

Nephron Exp Nephrol. 2003;95(1):e36-42. doi: 10.1159/000073022.

Abstract

Background: Transforming growth factor beta 1 (TGF-beta1) induces alpha2(I) collagen gene (COL1A2) expression in mesangial cells through physical and functional cooperation of Smad proteins and Sp1. A transcriptional coactivator, p300, is also suggested to play an important role in TGF-beta1/Smad signal transduction. However, the role of p300 in TGF-beta1/Smad-pathway-mediated transcriptional activation of the COL1A2 gene in mesangial cells is still obscure.

Methods: Endogenous p300 expression and its modulation by TGF-beta1 were evaluated by Western blotting and immunofluorescence. The physical interaction of p300 with Smad2/3 was examined by immunoprecipitation followed by Western blotting. The functional role of p300 in TGF-beta1/Smad-pathway-mediated COL1A2 transcription was investigated in cotransfection experiments using a COL1A2 promoter-luciferase reporter gene construct and p300 expression plasmids.

Results: TGF-beta1 induced COL1A2 gene expression in cultured mouse mesangial cells which was blocked by overexpression of inhibitory Smad7. In addition, TGF-beta1-induced nuclear export of endogenous Smad7 was observed in mouse mesangial cells. Endogenous p300 was expressed in the nucleus of the cells. TGF-beta1 induced interaction of endogenous p300 with Smad2/3, and a dominant negative construct of p300 inhibited the TGF-beta1-induced COL1A2 expression in cultured mouse mesangial cells.

Conclusions: p300 may be involved in TGF-beta1/Smad-pathway-mediated type I collagen gene transcription in mouse mesangial cells. Our findings would reveal a molecular basis of TGF-beta1-induced type I collagen gene transcription in mouse mesangial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Collagen / biosynthesis*
  • Collagen / genetics
  • Collagen Type I
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology*
  • E1A-Associated p300 Protein
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Genes, Dominant
  • Genes, Reporter
  • Glomerular Mesangium / cytology
  • Glomerular Mesangium / drug effects
  • Glomerular Mesangium / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Smad7 Protein
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Trans-Activators / physiology*
  • Transforming Growth Factor beta / metabolism*
  • Transforming Growth Factor beta / pharmacology

Substances

  • Collagen Type I
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Smad7 Protein
  • Smad7 protein, mouse
  • Trans-Activators
  • Transforming Growth Factor beta
  • Collagen
  • E1A-Associated p300 Protein
  • Ep300 protein, mouse