Fig. 4

Activation of ER-stress and autophagy in subject 3. a Western blot images showing increased expression of the endoplasmic reticulum (ER) chaperone GRP78, ER stress marker AFT6, and importantly the p50 (cleaved form) of ATF6 in HPS-2 patient lungs. In addition, the autophagy marker LC3B (active lipidated form is LC3BII) and SQSTM1/p62 are concomitantly increased, indicating defective autophagy in HPS-2 patient lungs (HPS-2 = patient 3, samples from two different sites of a lung, controls = organ donors). b Representative Western blot images for the myofibroblast marker alpha-SMA and loading control, beta-actin in lung homogenates of patient 3 (HPS-2, duplicate lanes with samples from two different sites of a lung), and 3 different organ donors (controls, one lane each). c Increase in ER stress marker ATF6 in alveolar epithelial type II cells in HPS-2 patient lungs. Representative images of immunohistochemistry for ATF6 and proSP-C (SP-C, alveolar epithelial type II cells marker) performed on serial paraffin sections of HPS-2 and organ donor lungs. Shown here are low and high magnification images, using 5×, 10× and 40× objective for both HPS-2 and donor lung sections. Far right images indicate same alveolar epithelial type II cells stained for both ATF6 and SP-C indicating many alveolar epithelial type II cells positively stained for ATF6. Scale bar: as indicated in the images. d Control sections represent ATF6 and SP-C stainings in donor lung sections, where almost no ATF6 is detected in SP-C positive alveolar epithelial type II cells