Elucidating the role of Fra1 in pancreatic Kras-driven acinar to ductal metaplasia

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PROJECT SUMMARY (ABSTRACT) Acute and chronic pancreatitis afflict millions of individuals in the US. Mouse models have revealed that acinar cells can de-differentiate after pancreatic injury to a progenitor-like cell type with ductal characteristics in a process termed acinar-to-ductal metaplasia (ADM). In the absence of oncogenic mutations, ADM lesions can resolve and reform the acinar compartment. However, in the presence of oncogenic Kras mutations, the ADM lesions can continue to de-differentiate to a pre-invasive pancreatic intraepithelial neoplasia (PanIN). The mechanisms that drive PanIN formation in the context of injury and oncogenic mutations are poorly understood, resulting in an absence of targets to combat the persistent ADM. We have identified previously through bulk ATAC-sequencing that the transcription factor Fra1 is differentially active only in the context of mutant Kras and acute inflammation. We have also generated a unique mouse model expressing inducible mutant KRAS (iKras) and Fra1 loxp alleles (Fra1 KO) in a pancreatic epithelial- specific manner. Our preliminary studies demonstrate that Fra1 loss attenuates ADM formation and stromagenesis compared to the FRA1 WT controls. The overarching goal of this proposal is to understand how FRA1 and its interacting partners, which constitute the AP-1 complex, govern ADM progression in the context of mutant Kras and inflammation. My hypothesis is that FRA1 is a central mediator of ADM. I will investigate the cell autonomous and non-cell autonomous effects driving FRA1 activation through the following interrelated Specific Aims: (1) Investigate how Fra1 remodels chromatin in ADM after induction of pancreatitis; (2) Elucidate the role of fibroblast-secreted G-CSF in Fra1 induction during pancreatitis. I will use novel mouse models, ex vivo 3D acinar and ADM cell cultures, and state-of-the-art single-cell sequencing and chromatin precipitation assays to conduct this study. This proposal also encompasses a translational aspect by proposing G-CSFR as a novel therapeutic target for the treatment of acute pancreatitis. Additionally, this project incorporates aspects of pathophysiology, molecular/cellular biology, and quantitative data analysis. This proposal provides me with a robust foundation in both experimental and quantitative analysis and broadens my fundamental knowledge of pancreatic epithelial cell homeostasis and plasticity. With the guidance from experienced mentors (Drs. Rustgi and Sims), my advisory committee and the rich array of resources at Columbia University Irving Medical Center, I will be able to complete my predoctoral PhD training. Completion of this critical milestone will set the stage for my long-term goal as a physician-scientist who conducts basic and translational research in an academic medical center with a focus on tissue inflammation, cellular identity and plasticity, and tissue regeneration.