Thursday, April 25, 2024
4/25/2024
Project Summary/Abstract Idiopathic pulmonary fibrosis (IPF) is a disease of progressive interstitial fibrosis, which leads to severe debilitation and eventually respiratory failure and death. Recent studies have implicated endoplasmic reticulum stress (ER stress) and the resulting unfolded protein response (UPR) in the pathophysiology of pulmonary fibrosis, including findings of increased UPR signaling and epithelial cell apoptosis in patients with hereditary and sporadic IPF. Despite these observations, it remains unclear how UPR activation leads mechanistically to fibrosis. The laboratory of Dr. Feroz Papa (co-sponsor) has developed KIRA8, a highly specific small molecule inhibitor of IRE1a, the most deeply-conserved mediator of the UPR. In unpublished work, the Sheppard and Papa laboratories (sponsor and co-sponsor, respectively) have shown that KIRA8 decreases markers of fibrosis in mice exposed to bleomycin. TGFß is a well-established driver of tissue fibrosis. Mice lacking integrin avß6, a critical activator of extracellular, latent TGFß, exhibit decreased UPR signaling and are correspondingly protected from fibrosis. In the MLE12 lung epithelial cell line, KIRA8 inhibition of IRE1a decreases SMAD2 phosphorylation, an early step in the TGFß signaling pathway. Together, these data suggest the central model of the proposal: that TGFß and UPR signaling conspire to promote excessive collagen deposition and pathological fibrosis. The proposed research will dissect the molecular mechanisms by which the UPR enhances TGFß signaling and fibrosis. The first aim of the study seeks to identify and characterize the relevant cell types undergoing ER stress in the lungs of mice exposed to bleomycin, using immunofluorescence staining and cell-type specific purification of messenger RNA (mRNA) and microRNA (miRNA) from epithelial cells and fibroblasts. The second aim of the study will probe interactions between TGFß signaling and the UPR in cell lines and mice. Because IRE1a is known to modulate miRNAs that are thought to regulate components of the TGFß signaling pathway, modulation of miRNAs is likely to be a mechanism by which the UPR enhances TGFß signaling. In cell lines, TGFß signaling will be evaluated after the UPR has been activated or inactivated by chemical and genetic techniques. Levels of miRNAs, particularly miR-17, miR-200, and miR-150, will be measured by quantitative PCR, and regulation of candidate miRNA targets evaluated by dual luciferase assay. These results will be extended in vivo by analyzing mRNA and miRNA purified from epithelial cells and fibroblasts. The proposed studies will advance the fundamental understanding of the mechanisms of pulmonary fibrosis and offer novel targets for therapy of this devastating disease.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).
