FIG. 3.

Comparison of regulation of K15 and K14 keratin gene expression by T3, RA, and GR receptors in HeLa cells. The K15 construct (A) and K14 construct (B) were cotransfected along with plasmids expressing cT3R-α and hRAR-γ receptors, and the transfected cells were incubated in the presence or absence of T3, RA, or dexametasone (DEX). The basal activities of the promoters were considered to be 1, and the relative activities in the presence of ligands and cotransfected receptors were determined. The β-galactosidase activities from cotransfected LacZ-expressing vector, which do not change in response to nuclear receptors, were used to normalize the CAT activities. (C and D) Regulation of the positive control plasmids, GH-CAT and GRE-CAT. While GH-CAT and GRE-CAT are induced by the corresponding ligands, K14 is suppressed by all three. Importantly, the K15 and K14 promoters are affected in opposite ways from each other in response to T3 and T3R.