PROJECT SUMMARY Necrotizing enterocolitis (NEC) is a devastating inflammatory disease that affects the intestine of premature infants. There is major gap in our understanding of the pathophysiology of NEC, including no cure for this often deadly disease. This proposal aims to help fill the knowledge gap by defining the role of the developmentally expressed mRNA binding protein IMP1 in the intestine during NEC. IMP1 plays roles in intestinal barrier maintenance, immune cell activation, intestinal stem cells, autophagy, and extracellular vesicles (EVs), which could all effect NEC etiology; however, the role of IMP1 in NEC is not known. Herein I will test the hypothesis that the RNA binding protein IMP1 post-transcriptionally promotes direct cell-to-cell and indirect vesicle-mediated communication in the intestine to impact barrier and immune function and NEC development. In Aim 1, we will utilize genetic mouse models where Imp1 is conditionally deleted or overexpressed in the intestinal epithelium to compare physiological and molecular responses to NEC challenge with a focus on intestinal barrier function. We will perform RNA immunoprecipitation (RIP)-sequencing to identify novel Imp1 binding targets in the neonatal intestine and during NEC, validate key targets in patient-derived enteroid models, and examine mechanisms in monolayer culture systems. In Aim 2, we will identify the role of Imp1 in EV communication and intestinal macrophage activation to protect against NEC. This will be achieved through direct analysis of EV cargo and intestinal macrophages. We will examine interactions between EVs, immune cells, and the epithelium using murine and patient-derived enteroids to define mechanisms governing barrier function and NEC etiology. Studies of IMP1 will elucidate novel mechanisms of post-transcriptional regulation of intestinal epithelial communication, with the potential to contribute significantly to our understanding of NEC. My goal is to become a successful, i