Mu Qinghui, Ha Andrew, Santos Antonio J M, Lo Yuan-Hung, van Unen Vincent, Miao Yi, Tomaske Madeline, Guzman Veronica K, Alwahabi Samira, Yuan Jenny J, Deng Lu, Li Linheng, Garcia K Christopher, Kuo Calvin J
Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Dev Cell. 2025 Feb 3;60(3):342-351.e5. doi: 10.1016/j.devcel.2024.10.022. Epub 2024 Nov 22.
The rapidly regenerating intestinal epithelium requires crypt intestinal stem cells (ISCs). Wnt/β-catenin signaling maintains crypt homeostasis and Lgr5+ ISCs, and WNT ligands bind Frizzled receptors (FZD1-10). Identifying specific FZD(s) essential for intestinal homeostasis has been elusive; however, bioengineered antagonists blocking Wnt binding to FZD5 and FZD8 deplete the gut epithelium in vivo, highlighting potential roles. Here, an epithelial-specific Fzd5 knockout (KO) elicited lethal pan-intestinal crypt and villus loss, whereas an Lgr5+ ISC-specific Fzd5 KO depleted Lgr5+ ISCs via premature differentiation and repressed Wnt target genes. Fzd5-null phenotypes were rescued by constitutive β-catenin activation in vivo and in both mouse and human enteroids. KO of Fzd5, not Fzd8, in enteroids ablated responsiveness to dual-specificity FZD5/FZD8-selective Wnt surrogate agonists, which ameliorated DSS-induced colitis in wild-type and Fzd8 KO mice. Overall, FZD5 is a dominant and essential regulator of crypt homeostasis, Lgr5+ ISCs, and intestinal response to Wnt surrogate agonists, with implications for therapeutic mucosal repair.
快速再生的肠道上皮需要隐窝肠道干细胞（ISC）。Wnt/β-连环蛋白信号通路维持隐窝稳态和Lgr5⁺ ISC，WNT配体与卷曲受体（FZD1-10）结合。确定对肠道稳态至关重要的特定FZD一直难以实现；然而，生物工程拮抗剂阻断Wnt与FZD5和FZD8的结合会在体内耗尽肠道上皮，突出了其潜在作用。在这里，上皮特异性Fzd5基因敲除（KO）引发致命的全肠道隐窝和绒毛丢失，而Lgr5⁺ ISC特异性Fzd5基因敲除通过过早分化耗尽Lgr5⁺ ISC并抑制Wnt靶基因。在体内以及在小鼠和人类肠类器官中，组成型β-连环蛋白激活挽救了Fzd5基因敲除的表型。在肠类器官中敲除Fzd5而非Fzd8消除了对双特异性FZD5/FZD8选择性Wnt替代激动剂的反应，这改善了野生型和Fzd8基因敲除小鼠中右旋糖酐硫酸钠（DSS）诱导的结肠炎。总体而言，FZD5是隐窝稳态、Lgr5⁺ ISC以及肠道对Wnt替代激动剂反应的主要且关键的调节因子，对治疗性黏膜修复具有重要意义。
