The homeostasis of the intestinal epithelium relies on intricate yet insufficiently understood mechanisms of intestinal epithelial plasticity. In this study, we elucidate the role of Frizzled5 (Fzd5), a Wnt pathway receptor, as a determinant of intestinal epithelial cell fate. Unlike other Frizzled receptors, Fzd5 exhibits broad expression throughout the crypt-villus axis, with enrichment in the upper crypt regions. Deletion of Fzd5 in Lgr5⁺ intestinal stem cells (ISCs) resulted in compromised self-renewal capacity. Moreover, the lineage-tracing ability of Krt19+ cells, primarily localized in the upper crypts, was impaired in the absence of Fzd5. Notably, these alterations did not disrupt crypt integrity. Conversely, Fzd5 knockout across the entire epithelium by the Villin-CreERT2 model led to severe crypt deterioration. Single-cell RNA sequencing (ScRNA-seq) unveiled significant changes in RNA profiles primarily within ISCs and progenitor cells. Furthermore, CUT&Tag analysis targeting the transcription initiator Pol II, histone activator H3K4me3, and histone repressor H3K27me3 demonstrated that alterations in transcription could be attributed to parallel changes at the chromatin level. Integrated analyses of ScRNA-seq and single-cell ATAC-seq (ScATAC-seq) revealed that Fzd5 governs chromatin accessibility, orchestrating the regulation of stem and lineage-related gene expression mainly in ISCs and progenitor cells. This regulatory effect primarily involves the activation of Tcf/β-catenin signaling and the repression of Smad2 signaling. Remarkably, supplementation with Wnt ligands could partially rescue the effects of Fzd5 knockout in intestinal organoids. In summary, our findings provide novel insights into the regulatory role of Wnt signaling in governing intestinal epithelial plasticity.

Fzd5 deletion in IECs results in crypt loss and lineage priming towards enterocytes

Fzd5 deletion alters chromatin accessibility to modulate gene expression in ISCs and progenitors

Xi He

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FRIZZLED5 REGULATES INTESTINAL EPITHELIAL CELL PLASTICITY THROUGH THE ORGANIZATION OF CHROMATIN ACCESSIBILITY

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