Abstract:
Objective To explore the molecular mechanism of the expression of forkhead box P3 (Foxp3) activated by particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) in human bronchial epithelial (BEAS2B) cells.
Methods The BEAS2B cells were treated with 300 μg/ml PM2.5 dissolved in phosphate buffered saline (PBS) for 48 hours and the BEAS2B cells treated only with PBS were taken as the control. After being treated with PM2.5 for 24 hours, the cells were also treated with 5.0 μM 5-azacytidine (5-AzaC) – a DNA methyltransferase inhibitor or 0.2 μM trichostatin A (TSA) – a histone deacetylase inhibitor, and the BEAS2B cells treated only with PM2.5 were taken as the control. The expression of Foxp3, homeobox A1 (HOXA1) and homeobox A2 (HOXA2) were detected with reverse transcription real-time PCR (RT-PCR) assay. The expression of DNA methyltransferases (Dnmts)-related protein was determined with Western blot and the DNA methylation level was measured with methylation-specific PCR (MSP-PCR).
Results Compared to those in the control group, the expression of Foxp3 and DNA methyltransferase 3a (Dnmt3a) in BEAS2B cells treated with PM2.5 were increased by 1.15 and 1.51 folds (both P < 0.05); while the expression of DNA methyltransferase 1 (Dnmt1) and DNA methyltransferase 3b (Dnmt3b) were decreased by 0.51 and 0.38 fold (both P < 0.05), respectively. Moreover, after the cells being treated with 5-AzaC or TSA, the expression of Foxp3 was increased by 1.61 or 1.20 folds (both P < 0.05), with the significantly down-regulated expressions of hypomethylation of Foxp3 promoter and the Dnmt1 protein (both P < 0.05).
Conclusion The expression of Foxp3 may be activated by PM2.5 through inhibiting the expression of Dnmt1.
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