Fig. 7.
PM2.5 exposure suppresses the activity of IRE1α in splicing the Xbp1 mRNA. A: detection of unspliced and spliced forms of Xbp1 mRNAs in macrophage cell line RAW264.7 exposed to PM2.5 and/or TM by semiquantitative RT-PCR analysis. RAW264.7 cells were exposed to PM2.5 (300 μg/ml) for 30 min and then treated with tunicamycin (TM, 2 μg/ml) for the time course as indicated. RAW264.7 cells treated with vehicle PBS buffer or with TM for 6 h were included as controls. The size of amplified unspliced Xbp1 mRNA is 170 bp, and the size of amplified spliced Xbp1 mRNA is 144 bp. Levels of β-actin mRNA were determined as internal controls. B: detection of unspliced and spliced forms of Xbp1 mRNAs in mouse hepatocyte cell line H2.35 exposed to PM2.5, TM, or PM2.5 plus TM by semiquantitative RT-PCR analysis. H2.35 cells were exposed to PM2.5 (300 μg/ml) or TM (2 μg/ml) for 2 to 6 h. Additionally, H2.35 cells were exposed to PM2.5 (300 μg/ml) for 30 min and then treated with TM (2 μg/ml) for 2 to 6 h. The cells treated with vehicle PBS buffer were included as the control. Levels of β-actin mRNA were determined as internal controls. For A and B, the experiments were performed at least in triplicate, and the representative data are shown. C: a schematic diagram depicting ER stress response induced by PM2.5 in mouse lung and liver tissues.