Abstract 5636: CUX1 transcriptionally regulates intestinal epithelial homeostasis
Authors: Zawieracz Katarzyna , An Ningfei , McNerney Megan 
Published: March 2024

Abstract
The small intestine digests and absorbs nutrients, a role made possible by specialized secretory and absorptive cells that constantly replenish from the intestinal stem cell niche. Disruption in intestinal epithelium homeostasis has been linked to pathologies including inflammatory bowel disease (IBD) and cancer. However, the processes regulating differentiation in healthy and disease setting are incompletely understood. CUX1 is a highly conserved homeodomain-containing transcription factor that is expressed in small intestinal crypts and has been previously shown to be essential in mice and Drosophila. CUX1 is upregulated upon inflammatory stress conditions, including intestinal damage and in IBD. In addition, CUX1 is predicted to be protective against IBD from genome-wide association studies. The aim of the current work is to determine the mechanistic role of CUX1 in secretory intestinal cells differentiation and epithelial homeostasis. To this end, we have generated transgenic mouse models that modulate CUX1 levels in an inducible manner. Mice with near-null CUX1 levels exhibit rapid weight loss requiring euthanasia while mice with ~50% residual CUX1 halt normal weight gain. Histologic examination of tissues from mice with CUX1 knock-down reveals a lack of mature secretory cells, including goblet and Paneth cells, the latter playing a supportive role to intestinal stem cells. Moreover, mouse intestinal tissues from our knock-down models demonstrated decreased proliferation with increased apoptosis. In transcriptome profiling, we observed downregulation of proliferation, intestinal stem cell, and digestive system developmental gene signatures and decreased levels of key secretory cell regulators, pointing towards a role for CUX1 in stem cell maintenance and differentiation. Indeed, reducing CUX1 levels decreased β-catenin protein levels, while Wnt/β-catenin signaling is required for the organization of the crypt-villus axis. Finally, CUX1 knock-down compromises the ability to form budding organoids, demonstrating the cell intrinsic role for CUX1 in stem cell differentiation. In ongoing studies, we are identifying CUX1 genome-wide binding targets and the epigenetic impact of CUX1 in intestinal epithelium cells. Our findings indicate that CUX1 is a critical regulator of intestinal epithelium homeostasis that has a role in differentiation and potential role in injury-induced de-differentiation in healthy as well as IBD patients. We propose that CUX1 regulates stem cell maintenance and crypt composition by regulating Wnt/β-catenin signaling and inducing fetal-like transcriptomic repair program shown to be coopted by colon cancers. Resolving an intricate network of transcriptional regulation of differentiation in the intestinal crypt holds the potential to successfully target inflammation-related damage in human intestines.
Citation Format: Katarzyna Zawieracz, Ningfei An, Megan McNerney. CUX1 transcriptionally regulates intestinal epithelial homeostasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5636.