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A decrease in intracellular zinc level precedes the detection of early indicators of apoptosis in HL-60 cells
J Y Duffy1, C M Miller, G L Rutschilling
1Miami Valley Laboratories, Procter & Gamble Co., Cincinnati, Ohio 45253, USA. dufo6m@chmcc.org
Summary
Low intracellular zinc levels trigger apoptosis, a programmed cell death. Decreased zinc precedes mitochondrial dysfunction and cell membrane changes, indicating zinc
Area of Science:
- Cell Biology
- Biochemistry
- Toxicology
Background:
- Low extracellular zinc is linked to apoptosis.
- Understanding intracellular zinc's role in apoptosis is crucial.
Purpose of the Study:
- To investigate the relationship between intracellular zinc concentration and apoptosis rate.
- To determine if zinc depletion precedes apoptosis markers.
Main Methods:
- Cells were cultured in varying zinc concentrations (0.5, 25, 50 microM).
- Intracellular zinc was measured using the fluorophore zinquin.
- Apoptosis markers, including mitochondrial transmembrane potential and cell membrane polarity, were assessed via flow cytometry and fluorescence microscopy.
Main Results:
- Cells in 0.5 microM zinc medium showed decreased intracellular zinc over 48 hours.
- Reduced rhodamine 123 retention (indicating mitochondrial dysfunction) was observed after 18 hours.
- Annexin V-FITC binding (an early apoptosis marker) increased after 30 hours.
- Restoration of zinc levels partially reversed mitochondrial changes.
Conclusions:
- Decreased intracellular zinc concentration precedes key early markers of apoptosis.
- Alterations in mitochondrial transmembrane potential occur before cell membrane polarity loss during zinc-induced apoptosis.