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Early elemental and ionic changes in cultured cells after stimulation with epidermal growth factor
J E Beesley1, S R Hall, M J Page
1Wellcome Research Laboratories, Beckenham, Kent, U.K.
Scanning Microscopy
|March 1, 1995
Summary
Epidermal growth factor (EGF) stimulation affects intracellular calcium, sodium, and potassium levels in A431 cells. Extracellular calcium is crucial for sustained calcium elevation and cell morphology following EGF stimulation.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Epidermal Growth Factor (EGF) is a potent mitogen that regulates cell growth and differentiation.
- Ionic homeostasis, particularly calcium (Ca2+), sodium (Na+), and potassium (K+), is critical for cellular function.
- A431 cells, a human vulval epidermal cell line, are commonly used to study EGF receptor signaling.
Purpose of the Study:
- To investigate the role of extracellular calcium in EGF-induced intracellular ionic changes in A431 cells.
- To examine the effects of EGF on ion fluxes (Na+, K+) and calcium levels in different cell lines.
- To assess EGF-induced morphological changes, particularly mitochondrial integrity.
Main Methods:
- A431 cells were stimulated with EGF (50 ng/ml) in the presence and absence of extracellular calcium.
- Intracellular ionic Ca2+, elemental Na, and K levels were measured.
- Changes in cell morphology, including mitochondrial structure, were observed.
- Responses of genetically engineered rodent fibroblast cell lines (NR6/SA3, NR6/DC7) to EGF were compared with A431 cells.
Main Results:
- EGF stimulation in the presence of extracellular calcium caused a sharp, sustained rise in intracellular Ca2+, increased Na, decreased K, and a rise in Ca.
- In the absence of extracellular calcium, the sustained Ca2+ rise was abolished, Na and K fluxes were variable, and Ca did not change.
- EGF induced significant morphological disruption in A431 cells, notably affecting mitochondria.
- NR6/SA3 and NR6/DC7 cells exhibited a higher response to EGF and higher resting cytoplasmic Ca2+ than A431 cells.
Conclusions:
- Extracellular calcium is essential for the sustained elevation of intracellular Ca2+ and the maintenance of cell morphology following EGF stimulation.
- EGF significantly impacts ion homeostasis and cellular structure, with varying responses observed across different cell types.
- The study highlights the complex interplay between EGF signaling, extracellular calcium, and intracellular ion dynamics.