Fig. 6.

PrP^C promotes protoporphyrin IX-mediated synthesis of α-globin. A) K562 cells expressing vector, PrP^C, or PrP^Δ51-89 were cultured in the absence or presence of protoporphyrin IX and subjected to western blotting. Probing for α-globin reveals upregulation by protoporphyrin IX in all cell lines (lanes 1–3 versus 4–6), and significantly more in PrP^C-expressing cells (lane 5 versus 4 & 6). Ferritin is downregulated, and TfR upregulated by exposure to protoporphyrin IX, indicating depletion of cellular iron stores as expected (lanes 1–3 versus 4–6). Lysates from mouse RBCs provide a positive control for α-globin (lane 7). Reaction for β-actin provides a loading control. B) Quantification by densitometry confirms significantly more upregulation of α-globin by protoporphyrin IX in PrP^C relative to vector and PrP^Δ51-89-expressing cells. Data are Mean ± SEM of three independent experiments. ^**p < 0.01, ^***p < 0.001.