Small molecule inhibition of IRE1α kinase/RNase has anti-fibrotic effects in the lung
Fig 1
ER stress activates IRE1α to induce apoptosis in alveolar epithelial cells.
(A) Ethidium bromide-stained agarose gel of XBP1 cDNA amplicons. Mouse Lung Epithelial (MLE12) cells were exposed to Tunicamycin (Tun) 2.5 μg/ml and indicated concentrations of STF-083010 for 4 hrs. The cDNA amplicon of unspliced XBP1 mRNA is cleaved by a PstI site within a 26 nucleotide intron to give 2U and 3U. IRE1α-mediated cleavage of the intron and re-ligation in vivo removes the PstI site to give the 1S (spliced) amplicon. * denotes a spliced/unspliced XBP1 hybrid amplicon. The ratio of spliced over (spliced + unspliced) amplicons—1S/(1S+2U+3U)—is reported as %XBP1 splicing under the respective lanes. (B) Percent MLE12 cells staining positive for Annexin V after treatment with Tm (30 ng/ml) and STF-083010 (50 μM) for 72 hrs. (C) Percent primary mouse alveolar epithelial cells (AEC) staining positive for Annexin V after treatment with Tm (100 ng/ml) and STF-083010 (62.5 μM) for 72 hrs. Three independent biological samples were used for Annexin V staining experiments. Data are means +/- SD. P value: * <0.05.