Analysis of the ATF3 gene promoter element required for activation by homocysteine.

(A) Scheme of the 5′-deletion constructs of the human ATF3 gene promoter fused to the luciferase gene. At the top, putative elements of the ATF3 gene promoter are shown.30 The numbers shown on the ATF3 promoter-luciferase cDNA constructs indicate the 5′-end positions of the promoter sequence. The construct pLuc-1850m, containing 2 base mutations in the ATF/CRE motif at −92 to −85, is shown at the bottom. (B) HUVECs were transfected with 2 μg of each plasmid and treated with 3 mmol/L homocysteine. The promoter activity was assayed as described in “Materials and methods” and expressed in arbitrary units. Fold induction is the ratio of homocysteine-stimulated activity (solid columns) to activity without homocysteine (open columns). The data represent the mean of 3 independent experiments with an SE bar. The fold induction was compared and tested with that of pLuc-1850; *P < .001, n = 3.