FIG. 3.

Potassium deprivation increases ATF activity rather than TRE activity. (A) CGNs were transfected with atf-luc plasmids and pCMV-RL in combination with plasmids encoding c-Jun-DN, ATF2-DN, or A-ATF2 (left panel). A dual-reporter analysis of dp5-luc or atf3-luc was performed with CGNs incubated in either 25 K or 5 K medium (right panel). The levels of luciferase activity were normalized to Renilla luciferase activity. (B) The levels of c-jun, dp5, and atf3 mRNA in CGNs in 25 K or 5 K medium for the indicated durations of time were measured, and β-actin mRNA was amplified as an input control. (C) Dual-reporter analysis of tre-luc or coll-luc in CGNs cultured in 25 K or 5 K medium. Data in this figure are presented as means ± standard errors of the means (SE) (three experiments). P < 0.05 (Student's t test).