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DNase I-hypersensitive sites enhance alpha1(I) collagen gene expression in hepatic stellate cells.

Liver fibrosis is characterized by a dramatic increase in the expression of type I collagen. Several deoxyribonuclease (DNase) I-hypersensitive sites (HS) have been located in the distal 5'-flanking region of the alpha1(I) collagen gene that are specific to collagen-producing cells. To assess the role of the DNase I-HS in regulating alpha1(I) collagen gene expression in hepatic stellate cells (HSCs), 3 transgenic mouse lines expressing collagen-alpha1(I) reporter genes were used (Krempen et al. Gene Expr 1999;8:151-163). The pCol9GFP transgene contains the collagen gene promoter (-3122 to +111) linked to the green fluorescent protein (GFP) reporter gene. The pCol9GFP-HS4,5 transgene contains HS4,5 and pColGFP-HS8,9 contains HS8,9 positioned upstream of the collagen promoter in pCol9GFP. HSCs isolated from transgenic mice containing pCol9GFPHS4,5 and pColGFP-HS8,9 showed earlier and higher GFP expression patterns than HSCs isolated from pCol9GFP mice. HSCs from pCol9GFP-HS4,5 showed the highest levels of GFP expression and culture-induced expression correlated with induction of the endogenous alpha1(I) collagen gene. After CCl(4) administration, pCol9GFP-HS4,5 mice showed increased GFP expression compared with pCol9GFP mice in both whole liver extracts and isolated HSCs. Several sites for DNA-protein interactions in both HS4 and HS5 were identified that included a binding site for activator protein 1. In conclusion, DNase I-HS4,5 enhance expression of the alpha1(I) collagen gene promoter in HSCs both in vitro and in vivo after a fibrogenic stimulus. The collagen-GFP transgenic mice provide a convenient and reliable model system to investigate the molecular mechanisms controlling increased collagen expression during fibrosis.

Pubmed ID: 12540776

Authors

  • Yata Y
  • Scanga A
  • Gillan A
  • Yang L
  • Reif S
  • Breindl M
  • Brenner DA
  • Rippe RA

Journal

Hepatology (Baltimore, Md.)

Publication Data

February 23, 2003

Associated Grants

  • Agency: NIAAA NIH HHS, Id: AA10459
  • Agency: NIAMS NIH HHS, Id: AR41909
  • Agency: NIDDK NIH HHS, Id: DK34987

Mesh Terms

  • Animals
  • Base Sequence
  • Binding Sites
  • Carbon Tetrachloride
  • Cells, Cultured
  • Collagen Type I
  • DNA
  • Deoxyribonuclease I
  • Gene Expression
  • Gene Expression Regulation, Enzymologic
  • Hepatocytes
  • Liver
  • Liver Cirrhosis
  • Mice
  • Mice, Inbred C3H
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • Proteins
  • Transgenes