A DNA element in the α1 type III collagen promoter mediates a stimulatory response by angiotensin II

G. M. Ghiggeri, R. Oleggini, L. Musante, G. Caridi, R. Gusmano, R. Ravazzolo

Research output: Contribution to journalArticle

Abstract

Background. Angiotensin II (Ang II) plays an important role in extracellular matrix deposition and tissue scarring in the kidney and the heart. The mechanism for extracellular matrix stimulation by Ang II is currently hypothetical, with one possibility pointing to a direct effect on cell synthesis of specific collagens. Methods. We studied the molecular mechanism for activation of type III collagen synthesis by Ang II in an in vitro cell model of myofibroblasts by evaluating (1) α1(III) collagen mRNA expression; (2) α1(III) collagen promoter activity; (3) DNA/protein binding with characterization of binding sites; (4) expression of transcription factors; and (5) the role of a short DNA segment as Ang II responsive element. Results. We found a specific dose-dependent stimulation of α1(III) collagen mRNA expression and a parallel effect on α1(III) collagen promoter activity. Transfection of constructs containing α1(III) collagen promoter fragments of different lengths localized the site of activation within the shortest 178 bp construct. By gel-retardation experiments, we observed the formation of a DNA-protein complex with crude extracts from Ang II-stimulated cells and an oligonucleotide spanning the 3 to 20 sequence. This complex was due to a sequence-specific interaction and was abolished by a 3 bp substitution mutation. The introduction of this mutation into the 178 bp construct abolished the stimulatory effect of Ang II. Conclusions. These results demonstrate that Ang II stimulates the expression of α1(III) collagen mRNA in myofibroblasts in vitro by activating the α1(III) collagen promoter at the level of a factor recognition site localized immediately downstream of the transcription start site. This mechanism could be involved in Ang II-induced renal and heart fibrosis.

Original languageEnglish
Pages (from-to)537-548
Number of pages12
JournalKidney International
Volume58
Issue number2
DOIs
Publication statusPublished - 2000

Keywords

  • Extracellular matrix
  • Heart fibrosis
  • Myofibroblasts
  • Proteinuria
  • Renal fibrosis
  • Transcription factors

ASJC Scopus subject areas

  • Nephrology

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