Fig. 6.

FcεRI increases intracellular free Zn levels, Zn wave: a type of early Zn signaling. a The intracellular Zn level increases within several minutes after antigen stimulation. To monitor the intracellular Zn level, mast cells were treated with the cell-permeable fluorescent Zn indicator Newport Green. Newport Green fluorescence remained steady in the cytoplasm, but gradually increased in the perinuclear and nuclear areas upon FcεRI stimulation. We named this phenomenon a “Zn wave.” b Early Zn signaling in mast cells. Extracellular antigen stimulation induces a Zn wave—a rapid alteration in intracellular Zn level—through the activation of Ca²⁺ and extracellular-signal-regulated kinase 1 and 2 (Erk1/2) signaling, which might positively affect the signal for inflammatory cytokine-mediated allergic reactions. This suggests that Zn has a role as an intracellular signaling molecule, transducing extracellular stimuli to physiological responses. Violet ovals Zn gatekeepers. (a Modified from Yamasaki et al. [21])