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Published on: June 15, 2017
Activation of c-Jun N-terminal kinase by cadmium in mouse embryo neural cells in vitro
Katharine M W Haberstroh1, Carolyn M Kapron
1Department of Biology and Watershed Ecosystems Graduate Program, Trent University, Peterborough, Ont., Canada K9J 7B8.
Abstract:
Members of the c-Jun NH(2)-terminal kinase (JNK) signalling pathway have been found to be stimulated by a variety of stresses, including heavy metals, hyperthermia, and UV-irradiation. In the present study, we examined whether exposure of micromass cultures of mouse embryonic midbrain cells to a known teratogen, cadmium, leads to the phosphorylation and activation of JNK. Midbrain cells exposed to 0.5, 1, 2, or 4μM cadmium chloride (CdCl(2)) showed a dose-dependent decline in cell numbers, cell viability and differentiation after 5 days. In cells exposed to 4μM CdCl(2) for up to 1h, the level of phosphorylated JNK increased by 15min and peaked at 30min exposure time, as determined by a phospho-specific anti-JNK antibody, while the total amount of JNK protein did not change. This phosphorylated JNK was active, as shown by a corresponding increase in the level of c-Jun phosphorylated on Ser63 in a kinase assay. These results demonstrate that CdCl(2) induces a rapid and transient activation of the JNK pathway in primary embryonic neuron cell cultures.
Insights
Cadmium chloride (CdCl2) exposure rapidly activates the c-Jun NH(2)-terminal kinase (JNK) pathway in mouse embryonic midbrain cells. This JNK pathway activation by cadmium indicates a potential mechanism for heavy metal-induced developmental toxicity.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- The c-Jun NH(2)-terminal kinase (JNK) pathway is activated by various cellular stresses.
- Heavy metals are known environmental stressors with potential teratogenic effects.
Purpose of the Study:
- To investigate if cadmium exposure activates the JNK signaling pathway in mouse embryonic midbrain cells.
- To determine the dose- and time-dependence of cadmium-induced JNK activation.
Main Methods:
- Micromass cultures of mouse embryonic midbrain cells were exposed to varying concentrations of cadmium chloride (CdCl2).
- Cell viability, proliferation, and differentiation were assessed.
- Western blotting with phospho-specific antibodies was used to measure JNK phosphorylation.
- Kinase assays were performed to confirm JNK activity.
Main Results:
- CdCl2 exposure resulted in a dose-dependent decrease in cell number, viability, and differentiation.
- A rapid and transient increase in phosphorylated JNK levels was observed within 15-30 minutes of CdCl2 exposure.
- Total JNK protein levels remained unchanged, indicating specific pathway activation.
- Increased phosphorylation of c-Jun confirmed the activation of JNK kinase activity.
Conclusions:
- Cadmium chloride rapidly activates the JNK signaling pathway in primary embryonic neuron cultures.
- This activation is transient and occurs independently of changes in total JNK protein levels.
- CdCl2-induced JNK pathway activation may contribute to the teratogenic effects of cadmium during embryonic development.
