Fig. 1

Mechanical overstretch selectively activates PERK ER stress signaling in porcine lung tissue. a. Perfused porcine lung complexes were prepared and randomized to receive low (LS, Vt = 6 ml/kg) or high stretch (overstretch, OS, Vt = 12 ml/kg) mechanical ventilation for 4 h or used as non-ventilated controls (NS). ER stress signal pathways were detected in extracted total protein using western blotting. Stretch did not affect Binding Immunoglobulin Protein (BiP) and X-box Binding Protein (XBP)-1 protein expression. OS significantly decreased the expression of cleaved form of Activating Transcription Factor (ATF) 6α (p50) compared to NS. We detected the activation of Protein Kinase RNA-like Endoplasmic Reticulum Kinase (PERK), eukaryotic Initiation Factor (eIF)-2α and the increased expression of downstream Integrated Stress Response proteins ATF4, CCAAT/Enhancer-binding Protein Homologous Protein (CHOP) and Growth Arrest and DNA Damage-inducible Protein (GADD)-34 expression. We used t-PERK for loading control of p-PERK, t-eIF2α for p-eIF2α and β-actin for other proteins. b-i. Quantified data is shown. Statistics: Kruskal-Wallis test was performed for multiple group comparison, and intergroup differences were analyzed with Wilcoxon rank sum test. N = 4 animals/group, p < 0.05. Data is presented as averaged values ±SEM in a five number summary format. * represents significant increase in p-PERK, p-eIF2α, ATF4, CHOP and GADD34 in OS and LS vs C conditions. # represents significant decrease in ATF6α expression in OS vs. NS conditions. The same abbreviations will be used in subsequent figures