ATM/ATR-related checkpoint signals mediate arsenite-induced G2/M arrest in primary aortic endothelial cells

Area of Science:

• Toxicology
• Cell Biology
• Cardiovascular Science

Background:

• Epidemiological studies link inorganic arsenic exposure to vascular disease.
• Arsenic-induced vascular endothelial dysfunction is a known factor.
• The role of arsenic-induced cell-cycle arrest in vascular dysfunction requires clarification.

Purpose of the Study:

• To investigate the regulatory mechanisms of G2/M phase arrest induced by arsenite in primary porcine aortic endothelial cells.
• To elucidate the involvement of specific cell cycle checkpoint molecules in arsenite toxicity.

Main Methods:

• Primary porcine aortic endothelial cells were treated with varying concentrations of arsenite (1-30 microM).
• Cell proliferation and G2/M phase arrest were assessed.
• Accumulation and phosphorylation of checkpoint proteins (p53, Cdc25B, Cdc25C, securin) were analyzed.
• The effect of caffeine on arsenite-induced G2/M arrest was evaluated.
• The roles of ATM and ATR kinases were investigated.

Main Results:

• Higher arsenite concentrations (10-30 microM) inhibited cell proliferation and induced G2/M phase arrest.
• Arsenite exposure led to the accumulation and/or phosphorylation of p53, Cdc25B, Cdc25C, and securin.
• Caffeine significantly attenuated arsenite-induced G2/M phase arrest by 93%.
• DNA damage responsive kinases ATM and ATR appear critical in mediating this arrest.

Conclusions:

• Arsenite induces G2/M phase arrest in aortic endothelial cells at higher concentrations.
• This arrest is regulated by ATM/ATR signaling pathways and involves key checkpoint molecules.
• Findings provide insight into mechanisms underlying arsenic-induced vascular dysfunction.