Figure 3. HIF expression level mediates cellular response towards survival under ammonia stress.

(A–C) Inhibitions of the HIF pathway results in improved ammonia tolerance. (A) Changes in the GI₅₀ of NH₄Cl were determined during HIF-1α depletion by shRNA and/or Flag-HIF-1α rescue overexpression. (B, C) Effect of 30 μM of a HIF-1α inhibitor 400083 (B) or PDK1 siRNA (C) on the GI₅₀ of NH₄Cl was tested in PEO1⁺ cells. (D, E) Apoptotic and live cell population were determined by Annexin-V assays upon 10 mM NH₄Cl treatment for the indicated time. CD90⁺ PEO1 cells were used in (A–E) which show the mean of n = 3 independent experiments. Error bars indicate s.e.m. ^*P < 0.05; ^**P < 0.01; ^****P<0.0001 (Student’s t-test).