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.

Grant Number: 1R03DK142841-01
NIH Institute/Center: NIH
Principal Investigator: Sarah Andres