Long- and short-term D-alpha-tocopherol supplementation inhibits liver collagen alpha1(I) gene expression.
We analyzed the role of oxidative stress on liver collagen gene expression in vivo. Long- and short-term supplementation with the lipophilic antioxidant D-alpha-tocopherol (40 IU/day for 8 wk or 450 IU for 48 h) to normal C57BL/6 mice selectively decreased liver collagen mRNA by approximately 70 and approximately 60%, respectively. In transgenic mice, the -0.44 kb of the promoter and the first intron of the human collagen alpha1(I) gene were sufficient to confer responsiveness to D-alpha-tocopherol. Inhibition of collagen alpha1(I) transactivation in primary cultures of quiescent stellate cells from these transgenic animals by D-alpha-tocopherol required only -0.44 kb of the 5' regulatory region. This regulation resembled that of the intact animal following D-alpha-tocopherol treatment and indicates that D-alpha-tocopherol may act directly on stellate cells. Transfection of stellate cells with collagen-LUC chimeric genes allowed localization of an "antioxidant"-responsive element to the -0.22 kb of the 5' region excluding the first intron. These findings suggest that oxidative stress, independently of confounding variables such as tissue necrosis, inflammation, cell activation, or cell proliferation, modulates in vivo collagen gene expression.
Chojkier
M
M
Department of Medicine, Veterans Affairs Medical Center, and Center for Molecular Genetics, University of California, San Diego, California 92161, USA.
Houglum
K
K
Lee
K S
KS
Buck
M
M
D000818:Animals; D002478:Cells, Cultured; D002678:Chimera / Q000235:genetics; D003094:Collagen / Q000235:genetics*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D017930:Genes, Reporter / Q000235:genetics; D019382:Human Growth Hormone / Q000235:genetics; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic / Q000235:genetics; D012016:Reference Values; D013997:Time Factors; D015533:Transcriptional Activation / Q000187:drug effects; D014810:Vitamin E / Q000494:pharmacology*
D019382:Human Growth Hormone; D014810:Vitamin E; D003094:Collagen