The PERK/ATF4 pathway is required for metabolic reprogramming and progressive lung fibrosis
Jyotsana Pandey, Jennifer L. Larson-Casey, Mallikarjun H. Patil, Chao He, Nisarat Pinthong, A. Brent Carter
Jyotsana Pandey, Jennifer L. Larson-Casey, Mallikarjun H. Patil, Chao He, Nisarat Pinthong, A. Brent Carter
View: Text | PDF
Research Article Immunology Pulmonology

The PERK/ATF4 pathway is required for metabolic reprogramming and progressive lung fibrosis

Abstract

Asbestosis is a prototypical type of fibrosis that is progressive and does not resolve. ER stress is increased in multiple cell types that contribute to fibrosis; however, the mechanism(s) by which ER stress in lung macrophages contributes to fibrosis is poorly understood. Here, we show that ER stress resulted in protein kinase RNA-like ER kinase (PERK; Eif2ak3) activation in humans with asbestosis. Similar results were seen in asbestos-injured mice. Mice harboring a conditional deletion of Eif2ak3 were protected from fibrosis. Lung macrophages from asbestosis individuals had evidence of metabolic reprogramming to fatty acid oxidation (FAO). Eif2ak3fl/fl mice had increased oxygen consumption rate (OCR), whereas OCR in Eif2ak3–/– Lyz2-cre mice was reduced to control levels. PERK increased activating transcription factor 4 (Atf4) expression, and ATF4 bound to the Ppargc1a promoter to increase its expression. GSK2656157, a PERK-specific inhibitor, reduced FAO, Ppargc1a, and Aft4 in lung macrophages and reversed established fibrosis in mice. These observations suggest that PERK is a therapeutic target to reverse established fibrosis.

Authors

Jyotsana Pandey, Jennifer L. Larson-Casey, Mallikarjun H. Patil, Chao He, Nisarat Pinthong, A. Brent Carter

×

Figure 1

Asbestos activates PERK in lung macrophages.

Options: View larger image (or click on image) Download as PowerPoint
Asbestos activates PERK in lung macrophages. (A) Lung macrophages from n...
(A) Lung macrophages from normal and asbestosis humans were obtained by bronchoalveolar lavage (BAL) and subjected to immunoblot analysis (n = 4). Densitometry of (B) phosphorylated (p-) PERK, (C) p-eIF2α, and (D) p-IRE1α in humans. (E) WT mice were exposed to man-made vitreous fiber (MMVF) or asbestos (100 μg intratracheally; i.t.). BAL was performed on day 21, and lung macrophages were subjected to immunoblot analysis (n = 3). Densitometry of (F) p-PERK, (G) p-eIF2α, and (H) p-IRE1α from exposed mice. (I) Macrophages were exposed to vehicle (Con), asbestos (Asb), tunicamycin (TUN), thapsigargin (TH), or 4PBA (PBA) and subjected to immunoblot analysis. Densitometry of (J) p-PERK and (K) p-eIF2α (n = 3). (L) Macrophages were exposed to vehicle or asbestos and stained for p-PERK. The staining was imaged by confocal microscopy, scale bars at 10 μm and 40×. (M) Quantification of mean fluorescence intensity (n = 3). Data shown as mean ± SEM. Two-tailed Student’s t test in B–D, F–H, and M. One-way ANOVA with Tukey’s post hoc comparison in J and K. *P ≤ 0.05, **P ≤ 0.01, and ****P ≤ 0.0001.