EFFECT OF ACETALDEHYDE ON SP1 BINDING AND ACTIVATION OF THE MOUSE ALPHA(2)(I) COLLAGEN PROMOTER

Acetaldehyde activates the mouse alpha(2)(I) collagen promoter and thi s effect is mediated in part by increased binding of nuclear factor I (NF-I). Additional mechanisms may exist since deletions in the promote r upstream to the NF-I binding site prevented enhancement by acetaldeh yde. Three adjacent areas of binding by nuclear proteins from activate d hepatic stellate cells were identified at -568 to -554 (region 1), - 542 to -518 (region 2), and -473 to -453 (region 3) of the promoter us ing DNase I protection analyses. Multiple DNA-protein complexes were f ormed in electrophoretic mobility shift assays with oligonucleotide pr obes specifying the three regions. Sp1 and NF-I bound to all three reg ions, while Sp3 bound to region 2. Acetaldehyde decreased nuclear prot ein binding to all three regions. Mutations of regions 1, 2, and 3 red uced basal activity of the promoter and inhibited acetaldehyde stimula tion in transfected stellate cells. Acetaldehyde inhibited the stimula tory effect of the Sp1 vector pPacSp1 on the promoter in transfected D rosophila cells. In conclusion, three regions of Sp1 binding were iden tified and are required for optimal activity of the alpha(2)(I) collag en promoter, Sp1 is required for basal activity of the alpha(2)(I) col lagen promoter; however, the enhancing effect of acetaldehyde on the p romoter is not mediated by Sp1. (C) 1997 Academic Press.