Background Cadmium is a common heavy metal pollutant. Previous studies mainly focus on cadmium-induced autophagy and apoptosis, but whether it leads to cell necroptosis remains unclear.
Objective This study investigates the mechanism of cadmium-induced necroptosis of mouse primary nerve cells.
Methods Mouse primary neurons were treated with 10 μmol·L-1 cadmium chloride for 2, 4, 6, 12, 24, and 48 h, respectively. The cell survival rate was calculated by Trypan blue staining. The changes of cell cycle (24 and 48 h) and the rate of cell necroptosis (48 h) after treatment with 10 μmol·L-1 cadmium chloride were detected by flow cytometry. The expressions of genes related to cell necroptosis such as receptor interacting serine threonine kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL) after being treated with 10 μmol·L-1 cadmium chloride for 48 h were measured by real-time fluorescence quantitative PCR. The protein expression of autophagy-related factor p62 and the fluorescence intensities of p62 and microtubule-associated protein 1 light 3-B (LC3-B) after 10 μmol·L-1 cadmium chloride treatment were analyzed by Western blotting and fluorescence observation.
Results The cell viability of mouse primary nerve cells were decreased after 4, 6, 12, 24, and 48 h treatment with 10 μmol·L-1 cadmium chloride (P < 0.05). Compared with the control group (49.62%), 60.88% and 82.94% of cells were arrested in the G0-G1 phase after treatment with 10 μmol·L-1 cadmium chloride for 24 h and 48 h, respectively. The flow cytometry results showed that when being treated with 10 μmol·L-1 cadmium chloride for 48 h, the rate of cell necroptosis was higher (47.5%) than that of the control group (0.01%), and the transcription of cell necroptosis related genes such as RIPK3 and MLKL were 6.9 and 3.7 times of the control group. The results of Western blotting showed that the expression of autophagyrelated protein p62 in mouse primary neurons were upregulated by (587±17)%, (609±14)%, and (893±16)% when being treated with 5, 10, and 20 μmol·L-1 cadmium chloride respectively. Further fluorescence observation showed that p62 and LC3-B were colocalizated and the fluorescence intensity levels of them were increased after cadmium treatment.
Conclusion Cadmium treatment could reduce the survival rate of mouse primary neurons, arrest the cell cycle in G0-G1 phase, and increase the necroptosis rate. The mechanism by which cadmium induce necroptosis may be related to the increased expressions of p62 and LC3-B and then the blocked autophagy flow.
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