FIG. 6.
AMPK activation is not required for REDD1 function. (A) DN-AMPK blocks phospho-S6K (T389) regulation by 2DG but not by REDD1. U2-REDD1 cells were infected with DN-AMPK or vector control adenovirus, and 24 h later cells were treated with tetracycline (Tet) to induce REDD1 or with 2DG (25 mM) for the indicated times (T4 and T8, 4 and 8 h of treatment, respectively). Note that DN-AMPK comigrates with endogenous AMPK. (B) DN-AMPK does not inhibit cell size regulation by REDD1. Histogram showing cell size (FSC-H) distribution of G1-gated U2-REDD1 cells infected as in panel A and then induced to express REDD1 (black line) or untreated (grey shading) for 48 h. (C) Quantitation of cell size decrease following induction of REDD1, which is unchanged in the presence or absence of DN-AMPK. The average of mean FSC-H values is shown for three independent experiments performed as in panel B. *, P < 0.005 versus (−)Tet for all comparisons. Error bars show 1 standard deviation.