Fig. 1.

NO derived from iNOS activity induces intranuclear Zn²⁺ release in MAEC. MAEC from WT (A–D), iNOS-deficient (E and F), or MT-deficient mice (G and H) were activated with IL-1β + TNF-α + IFN-γ for 24 h in the absence or presence of 250 μM of the iNOS-specific inhibitor l-NIO. Cells were then labeled with Zinquin, which specifically becomes fluorescent after reaction with labile, but not protein-bound, Zn²⁺. In activated WT MAEC, a bright Zn²⁺-specific fluorescence signal is located almost exclusively in the nuclei, with a punctate-staining pattern against a more diffuse nuclear background staining (A and B). In contrast, no Zn²⁺-specific fluorescence signal can be detected in activated WT MAEC cultured in the presence of l-NIO (C and D)or in MAEC deficient for either iNOS (E and F)orfor MT-1 + MT-2 (G and H). Thus, iNOS-derived NO, as well as MT, is essential for intranuclear Zn²⁺ release. (Scale bar = 5 nm.)