Background and rationale: The intestinal epithelium is a highly dynamic tissue that renews itself every few days to maintain the balance between absorption, barrier protection, and host defense. In inflammatory bowel disease (IBD), this homeostatic balance is disrupted by epithelial injury, resulting in compromised barrier function, chronic inflammation, and impaired regenerative capacity. Although current IBD therapies focus on modulating immune responses, there are no approved treatments that directly promote mucosal healing. Understanding the molecular regulators that coordinate epithelial repair is therefore essential for identifying new therapeutic targets. While transcriptional responses to injury are well-characterized, post-transcriptional regulation, particularly RNA modifications and RNA-binding proteins (RBPs), has only recently emerged as a critical mechanism for controlling rapid and context-specific gene expression. One such regulator is IGF2 mRNA-binding protein 1 (IMP1), a fetal RBP that is re-expressed in the adult gut following injury. IMP1 binds to specific mRNAs and has been shown to influence their stability, localization, and translation, often in coordination with N6-methyladenosine (m6A), the most abundant internal mRNA modification. Methods: We modeled hypoxia-associated epithelial injury using mouse colonoids cultured under 1% O 2 and by administering 3.5% DSS to mice both in vitro and in vivo. To identify direct RNA targets of IMP1, we performed RNA immunoprecipitation followed by sequencing (RIP-seq) and applied an IMP1-tagged ADAR-based RNA editing approach (HyperTRIBE) in colonoids. To define the spatial distribution and temporal dynamics of IMP1-expressing cells, we generated and characterized Imp1-CreERT2; Rosa26-LSL-tdTomato reporter mice. Results and Conclusions: IMP1 expression was markedly upregulated following hypoxic injury at both the RNA and protein levels. RIP-seq analysis of colonoids exposed to 24 hours of hypoxia (1% O 2 ) versus normoxia (20% O 2 ) revealed >5-fold enrichment of IMP1-bound transcripts involved in epithelial junctional integrity (e.g., Cldn4, Actb, Pard6b) and tissue regeneration (e.g., Col4a1, Col4a2, Basp1). These data suggest that hypoxia not only increases IMP1 abundance but also shifts IMP1 target selection toward pathways essential for maintaining barrier stability and promoting epithelial repair. Finally, Imp1-CreERT2; Rosa26-LSL-tdTomato reporter mice demonstrated robust and specific labeling of IMP1-expressing cells in the colonic epithelium, validating its utility for in vivo lineage tracing in ongoing studies. This research was funded by the Penn Presidential PhD Fellowship (IY), the NSF GRFP grant DGE-2146755 (IY), and the NIH grants R01DK124369 (KEH) and R01DK142682 (KEH). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Yannuzzi et al. (Fri,) studied this question.