Deciphering the Molecular Puzzle: IMP1 Modulation of Mucus Integrity in Necrotizing Enterocolitis - SUMMARY Necrotizing enterocolitis (NEC) is a devastating inflammatory disease that affects the intestines of premature infants. There is a major gap in our understanding of the factors that contribute to the pathophysiology of NEC, including no cure for this often deadly disease. This proposal aims to help fill the knowledge gap by defining a role of the developmentally expressed mRNA-binding protein IMP1 in intestinal mucus composition and survival during NEC. A healthy, mature mucus barrier is essential to protect the intestinal epithelium from inflammation. Our preliminary work shows that Imp1 expression promotes survival during NEC with concomitant upregulation of Qsox1, an enzyme involved in the final glycosylation step (sialyation) of mucus, which translates into the detection of less immature mucus in mice expressing Imp1 during NEC pathogenesis. Roles for IMP1 in NEC and intestinal mucus composition are not known. Understanding how Imp1 regulates Qsox1 and modulates mucus maturation could open new pathways for therapeutic development in NEC. Our long-term goal is to leverage post-transcriptional regulation of intestinal epithelial damage response to improve outcomes for infants at risk for or with NEC. The overall objective of this proposal is to delineate mechanisms of Imp1-mediated survival and intestinal mucus glycosylation. Our central hypothesis is that Imp1 promotes Qsox1 expression to enhance the mucus barrier and promote survival during NEC. Our specific aims are to 1) determine the impact of Imp1 expression on intestinal mucus composition throughout NEC pathogenesis and 2) define the requirement for Qsox1 in Imp1-mediated survival in NEC. Our approach will use Imp1 genetic mouse models combined with an experimental NEC-like intestinal injury model to define the impact of Imp1 on intestinal mucus, including glycosylation, permeability, ultrastructure, and intestinal proteomics during NEC. Key findings will be confirmed in human NEC tissue. We will define Imp1 target mRNAs in the NEC intestine and the Imp1 binding site within Qsox1 via crosslinking RNA immunoprecipitation. We will crossbreed Imp1 overexpressing and Qsox1 knockout mice to determine if Qsox1 is required for Imp1-mediated NEC survival. This research is innovative because it 1) links Imp1 to survival in NEC, 2) connects Imp1 to mucus regulation via Qsox1; 3) will define new molecular mediators of mucus composition in NEC. At the end of the project, we expect to 1) establish Imp1 as a regulator of mucus in NEC; 2) generate novel data connecting Imp1 to Qsox1 regulation and intestinal mucus; 3) use proteomics to uncover mechanisms by which Imp1 promotes survival in NEC; 4) define new pathways that could be leveraged for NEC prevention or treatment. Positive impact: This research will define a role for intestinal mucus in NEC and Imp1 as a new regulator of mucus maturation during inflammation, opening new lines of therapeutic investigation.
