Involvement of redox events in caspase activation in zinc-depleted airway epithelial cells.
Airway epithelial cells (AEC) contain both pro- and anti-apoptotic factors but little is known about mechanisms regulating apoptosis of these cells. In this study we have examined the localization of pro-caspase-3 and Zn(2+), a cellular regulator of pro-caspase-3, in primary sheep and human AEC. Zn(2+) was concentrated in both cytoplasmic vesicles and ciliary basal bodies, in the vicinity of both pro-caspase-3 and the antioxidant Cu/Zn superoxide dismutase (Cu/Zn SOD). Depletion of intracellular Zn(2+) in sheep AEC, using the membrane permeant Zn(2+) chelator TPEN, increased lipid peroxidation in the apical cell membranes (as assessed by immunofluorescence with anti-hydroxynonenal) as well as increasing activated pro-caspase-3 and apoptosis. There were smaller increases in caspase-2 and -6 but not other caspases. Activation of caspase-3 in TPEN-treated AEC was inhibited strongly by N-acetylcysteine and partially by vitamin C and vitamin E. These findings suggest that cytoplasmic pro-caspase-3 is positioned near the lumenal surface of AEC where it is under the influence of Zn(2+) and other anti-oxidants.
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D053148:Caspase 3; D020169:Caspases / Q000187:drug effects / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000187:drug effects / Q000378:metabolism*; D005029:Ethylenediamines / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000473:pathology; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000494:pharmacology; D020545:Respiratory Mucosa / Q000187:drug effects / Q000201:enzymology*; D012756:Sheep; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000172:deficiency* / Q000494:pharmacology*
D002614:Chelating Agents; D004792:Enzyme Precursors; D005029:Ethylenediamines; D030421:Peroxynitrous Acid; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D015032:Zinc; C044387:N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine