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Cytotoxic effect of beta-amyloid on a human differentiated neuron is not mediated by cytoplasmic Ca2+ accumulation
Z Y Gao1, H W Collins, F M Matschinsky
1Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104-6082, USA.
Abstract:
The effects of synthetic beta-amyloid (A beta1-42) on cell viability and cellular Ca2+ homeostasis have been studied in the human neuron-like NT2N cell, which differentiates from a teratocarcinoma cell line, NTera2/C1.D1, by retinoic acid treatment. NT2N viability was measured using morphological criteria and fluorescent live/dead staining and quantified using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide metabolism. A beta1-42 dose-dependently caused NT2N cell death when it was present in the cell culture for 14 days but had no effect on viability when it was present for 4 days. The lowest effective concentration was 4 microM, and the strongest effect was produced by 40 microM. Control NT2N cells produced spontaneous cytosolic Ca2+ oscillations under basal conditions. These oscillations were inhibited dose-dependently (0.4-40 microM) by A beta1-42 that was present in the cell culture for 1 or 4 days. Ca2+ wave frequency was decreased from 0.21 +/- 0.02 to 0.05 +/- 0.02/min, amplitude from 88 +/- 8 to 13 +/- 4 nM, and average Ca2+ level from 130 +/- 8 to 58 +/- 3 nM. The Ca2+ responses to 30 mM K+ and 100 microM glutamate were not different between control and A beta-treated cells. Thus, the results do not support the hypothesis that cytosolic early Ca2+ accumulation mediates A beta-induced NT2N cell death.
Insights
Synthetic beta-amyloid (A beta1-42) causes human neuron-like cell death after 14 days of exposure. It also inhibits calcium (Ca2+) oscillations, but does not appear to mediate cell death through early calcium accumulation.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Alzheimer's disease is characterized by amyloid plaques.
- Beta-amyloid (A beta) is implicated in neurodegeneration.
- Calcium homeostasis is crucial for neuronal function.
Purpose of the Study:
- To investigate the effects of synthetic beta-amyloid (A beta1-42) on NT2N cell viability.
- To examine the impact of A beta1-42 on cellular calcium (Ca2+) homeostasis.
- To determine if early cytosolic Ca2+ accumulation mediates A beta-induced cell death.
Main Methods:
- NT2N cells were treated with varying concentrations of A beta1-42.
- Cell viability was assessed using morphological criteria, live/dead staining, and MTT assays.
- Cytosolic Ca2+ oscillations and responses to K+ and glutamate were measured.
Main Results:
- A beta1-42 caused dose-dependent NT2N cell death after 14 days, with no effect at 4 days.
- A beta1-42 inhibited spontaneous Ca2+ oscillations in a dose-dependent manner.
- No significant differences in Ca2+ responses to K+ or glutamate were observed between control and A beta-treated cells.
Conclusions:
- Prolonged exposure to A beta1-42 induces cell death in human neuron-like cells.
- A beta1-42 disrupts Ca2+ homeostasis by inhibiting spontaneous oscillations.
- Early cytosolic Ca2+ accumulation is not the primary mechanism of A beta-induced NT2N cell death.