Characterization of pulmonary progenitor cell dysfunction in COPA syndrome

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PROJECT SUMMARY – ABSTRACT Coatomer protein subunit alpha (COPA) syndrome is a rare, autosomal dominant, monogenic disorder that results in a multiorgan disease affecting the lungs and joints with incomplete penetrance. Patients present early in life with interstitial lung disease (ILD) and have elevated inflammatory markers and positive autoantibody titers. While treatments exist to control this aberrant immune phenotype, they do not address the unknown mechanism(s) of this disease. COP is a ubiquitously expressed subunit of the coatomer protein complex I (COPI) which is responsible for retrograde transport of proteins from the Golgi to the ER. Alterations or disruptions in this pathway result in cellular stress. To date, most studies have examined the role of the immune system in the onset and progression of COPA syndrome without elucidating a cause for this disease. Therefore, we believe other cell types and processes are involved. Most COPA patients will at some point suffer from a spectrum of pulmonary disease such as bronchiolitis, ILD, and/or pulmonary fibrosis (PF). These diseases share certain pathogenic characteristics in response to cellular stress including, but not limited to, ER stress and unfolded protein response (UPR) activation, activated fibroblasts, inflammation, and aberrant autophagy. Progenitor cells of the proximal and distal lung, basal and alveolar type II cells (ATII), respectively, are disproportionally affected causing aberrant maintenance of the epithelium throughout the airway. We believe similar mechanisms of progenitor cell dysfunction are occurring in COPA syndrome patients. We therefore hypothesize that COPA syndrome is driven by an intrinsic progenitor cell defect that compromises epithelial maintenance resulting in ILD and lung fibrosis. In Aim 1, we will determine the epithelial cell- intrinsic defects resulting from the expression of COPAMT. This will be achieved by characterizing the COP interactome to elucidate anomalous protein interactions leading to cellular stress. We will then characterize the transcriptome of COPAMT using single cell RNA sequencing to highlight differential gene expression patters associated with disease. Furthermore, we will utilize in vivo mouse models to accurately describe the link between pulmonary progenitor cell dysfunction and activation of the immune responses associated with COPA syndrome. In Aim 2, we will validate strategies to rescue the epithelial cell defect of COPA syndrome using lentiviral vector delivery systems and gene editing tools with the intention of rescuing the diseased phenotype.