Up to 20% of idiopathic pulmonary fibrosis cases (IPF) are familial, comprising a syndrome known as Familial Interstitial Pneumonia (FIP). Short peripheral blood telomere length has been associated with sporadic IPF and FIP, and rare loss of function mutations in telomerase complex genes have been found in 15-20% of FIP families, however, investigations to date regarding the mechanisms linking telomerase dysfunction and telomere shortening with lung fibrosis have been largely unrevealing. Using whole-exome sequencing, we have recently identified loss-of-function mutations in regulator of telomere elongation helicase (RTEL1) that segregated with disease in 15 FIP families, and our preliminary data suggest impaired RTEL1 function leads to inefficient repair of DNA-damage in alveolar epithelial cells (AECs), leading to activation of p53 mediated cell- cycle arrest signalin programs that may contribute to AEC dysfunction in the context of pulmonary fibrosis. Using bioinformatics approaches, we identified a large group of FIP families (>50%) that carry rare variants in other genes related to cell cycle, DNA damage-repair, and p53 signaling, suggesting that abnormalities in these interrelated pathways may underlie genetic risk for a large subset of FIP families. In this proposal, we hypothesize that loss-of-function genetic variants in FIP-associated genes (including RTEL1) predispose to pulmonary fibrosis by altering DNA-damage repair and activating p53-mediated cell-cycle checkpoint arrest signaling in alveolar epithelial cells, resulting in impaired re-epithelialization following injury and progressive fibrotic remodeling.
Our specific aims are: (1) To determine the role of Rtel in experimental lung fibrosis. (2) To determine the mechanisms through which RTEL1 regulates DNA damage-repair and cell survival/proliferation in response to injury, and (3) To determine whether DNA damage-repair capacity is altered in a large subset of FIP families and patients with sporadic IPF. To accomplish these aims, we will utilize Rtel deficient mouse models, RTEL1 deficient cell lines, primary cells from Rtel deficient mice, and primary cells from FIP and IPF patients. Together, these studies hold the promise of elucidating the role of DNA-damage repair and signaling in the development of pulmonary fibrosis, thus adding important new insights into disease pathogenesis.

Public Health Relevance

RTEL1 mutations have recently been identified in families with pulmonary fibrosis, and our preliminary studies suggest RTEL1 may contribute to the development of disease by altering repair of DNA-damage. In this proposal, we will use cell and mouse models to investigate the mechanisms of RTEL1 mutations and test whether abnormal DNA repair is a common mechanism contributing to the development of pulmonary fibrosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08HL130595-03
Application #
9198576
Study Section
Special Emphasis Panel (MCBS (OA))
Program Officer
Colombini-Hatch, Sandra
Project Start
2016-01-01
Project End
2020-12-31
Budget Start
2017-01-01
Budget End
2017-12-31
Support Year
3
Fiscal Year
2017
Total Cost
$157,248
Indirect Cost
$11,648
Name
Vanderbilt University Medical Center
Department
Type
Independent Hospitals
DUNS #
079917897
City
Nashville
State
TN
Country
United States
Zip Code
37232
Sivley, R Michael; Sheehan, Jonathan H; Kropski, Jonathan A et al. (2018) Three-dimensional spatial analysis of missense variants in RTEL1 identifies pathogenic variants in patients with Familial Interstitial Pneumonia. BMC Bioinformatics 19:18
Burman, Ankita; Kropski, Jonathan A; Calvi, Carla L et al. (2018) Localized hypoxia links ER stress to lung fibrosis through induction of C/EBP homologous protein. JCI Insight 3:
Wilfong, Erin M; Lentz, Robert J; Guttentag, Adam et al. (2018) Interstitial Pneumonia With Autoimmune Features: An Emerging Challenge at the Intersection of Rheumatology and Pulmonology. Arthritis Rheumatol 70:1901-1913
Celada, Lindsay J; Kropski, Jonathan A; Herazo-Maya, Jose D et al. (2018) PD-1 up-regulation on CD4+ T cells promotes pulmonary fibrosis through STAT3-mediated IL-17A and TGF-?1 production. Sci Transl Med 10:
Hewlett, Justin C; Kropski, Jonathan A; Blackwell, Timothy S (2018) Idiopathic pulmonary fibrosis: Epithelial-mesenchymal interactions and emerging therapeutic targets. Matrix Biol 71-72:112-127
Kropski, Jonathan A; Blackwell, Timothy S (2018) Endoplasmic reticulum stress in the pathogenesis of fibrotic disease. J Clin Invest 128:64-73
Kropski, Jonathan A; Richmond, Bradley W; Gaskill, Christa F et al. (2018) Deregulated angiogenesis in chronic lung diseases: a possible role for lung mesenchymal progenitor cells (2017 Grover Conference Series). Pulm Circ 8:2045893217739807
Lentz, Robert J; Taylor, Trevor M; Kropski, Jonathan A et al. (2018) Utility of Flexible Bronchoscopic Cryobiopsy for Diagnosis of Diffuse Parenchymal Lung Diseases. J Bronchology Interv Pulmonol 25:88-96
Dressen, Amy; Abbas, Alexander R; Cabanski, Christopher et al. (2018) Analysis of protein-altering variants in telomerase genes and their association with MUC5B common variant status in patients with idiopathic pulmonary fibrosis: a candidate gene sequencing study. Lancet Respir Med 6:603-614
Sucre, Jennifer M S; Jetter, Christopher S; Loomans, Holli et al. (2018) Successful Establishment of Primary Type II Alveolar Epithelium with 3D Organotypic Coculture. Am J Respir Cell Mol Biol 59:158-166

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