Fig. 3.

Labilization of lysosomes by hydrogen peroxide and its modulation by autophagocytosed metallothioneins and endocytosed apo-ferritin, desferrioxamine and a Fe phosphate complex. J774 cells were exposed to hydrogen peroxide (initially 100 μM in PBS) for 30 min (H₂O₂), to PBS only (Control), or to H₂O₂ in combination with 100 μM of the lipophilic iron-chelator SIH—and then returned to standard culture conditions. Some cells had previously been exposed to the hydrophilic iron chelator desferrioxamine (1 mM) for 3 h, to 1 μM apo-ferritin (Apo-Ft) for 4 h, or a Ferric-phosphate complex (30 μM) for 4 h, while other cells had been exposed to ZnSO₄ for 12 h to induce the upregulation of metallothioneins and ensuing autophagy of this protein. Note that apo-ferritin, desferrioxamine, SIH, and metallothioneins stabilize lysosomes, while the Fe–phosphate complex has the opposite effect. The figure is compiled from a number of previously published ones