Lung epithelial transcriptional responses to bleomycin and effects of IRE1α or TGFβ inhibition. Lung epithelial transcriptional responses to bleomycin and effects of IRE1α or TGFβ inhibition

This experiment sought to characterize the epithelial-specific transcriptional response in the bleomycin model of lung fibrosis, and the contribution of IRE1a and the TGFb-activating integrin avb6 to this response. "Ribotag" mice were crossed to ShhCre mice, both on the C57BL/6 background to generate experimental cohorts. Mice used for the experiment conditionally expressed HA-tagged ribosomal protein Rpl22 in the epithelium. Mice were exposed to intranasal bleomycin (3 U/kg) on day 1 and subsequently treated with the IRE1a kinase inhibitor KIRA8 (50 mg/kg daily), or the anti-integrin beta6 antibody 3G9 (10 mg/kg on day 1 and day 4). Treatment controls were either drug vehicle (3% ethanol, 7% Tween80, and 90% saline) or the inert antibody Axum8 in saline). Lungs were harvested on day 7 after bleomycin exposure, flash-frozen, and later homogenized under native conditions with cycloheximide. An aliquot of the “input” homogenate was removed and total RNA purified by Qiagen RNeasy Mini and is representative of the whole-lung transcriptome/translatome. The remaining homogenate was subjected to immunoprecipitation of HA-tagged polysomes, followed by RNA purification by Qiagen RNeasy Micro, and is representative of the lung epithelial transcriptome/translatome. Overall design: Factorial design. Principal treatment groups are: Saline/Control (6 mice), Bleomycin/Control (9 mice), Bleomycin/KIRA8 (5 mice) and Bleomycin/3G9 (4 mice). Each mouse has a corresponding whole lung and epithelial library.