The Tight Junction Protein ZO-1 Is Dispensable for Barrier Function but Critical for Effective Mucosal Repair

• Published in: Gastroenterology (New York, N.Y. 1943) Vol. 161; no. 6; pp. 1924 - 1939
• Main Authors: Kuo, Wei-Ting, Zuo, Li, Odenwald, Matthew A., Madha, Shariq, Singh, Gurminder, Gurniak, Christine B., Abraham, Clara, Turner, Jerrold R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2021
• Subjects: Animals; Cell Proliferation; Cells, Cultured; Colon - metabolism; Colon - pathology; Databases, Genetic; Disease Models, Animal; Epithelial Cells - metabolism; Epithelial Cells - pathology; Humans; Inflammatory Bowel Disease; Inflammatory Bowel Diseases - genetics; Inflammatory Bowel Diseases - metabolism; Inflammatory Bowel Diseases - pathology; Intestinal Mucosa - metabolism; Intestinal Mucosa - pathology; Intestinal Permeability; Mice; Mice, Knockout; Mitosis; Mitotic Spindle; Permeability; Spindle Apparatus - genetics; Spindle Apparatus - metabolism; Spindle Apparatus - pathology; Wnt; Wnt Signaling Pathway; Wound Healing; Zonula Occludens-1 Protein - genetics; Zonula Occludens-1 Protein - metabolism; Mitosis; DSS; qRT-PCR; GSEA; Mitotic Spindle; IBD; mRNA; TNBS; 4-OHT; ZO-1; EdU; Intestinal Permeability; Inflammatory Bowel Disease; MDCK; Wnt; WT; NuMA
• ISSN: 0016-5085; 1528-0012
• DOI: 10.1053/j.gastro.2021.08.047

Increased permeability is implicated in the pathogenesis of intestinal disease. In vitro and in vivo studies have linked down-regulation of the scaffolding protein ZO-1, encoded by the TJP1 gene, to increased tight junction permeability. This has not, however, been tested in vivo. Here, we assessed the contributions of ZO-1 to in vivo epithelial barrier function and mucosal homeostasis. Public Gene Expression Omnibus data sets and biopsy specimens from patients with inflammatory bowel disease (IBD) and healthy control individuals were analyzed. Tjp1f/f;vil-CreTg mice with intestinal epithelial–specific ZO-1 knockout (ZO-1KO.IEC) mice and Tjp1f/f mice littermates without Cre expression were studied using chemical and immune-mediated models of disease as well as colonic stem cell cultures. ZO-1 transcript and protein expression were reduced in biopsy specimens from patients with IBD. Despite mildly increased intestinal permeability, ZO-1KO.IEC mice were healthy and did not develop spontaneous disease. ZO-1KO.IEC mice were, however, hypersensitive to mucosal insults and displayed defective repair. Furthermore, ZO-1–deficient colonic epithelia failed to up-regulate proliferation in response to damage in vivo or Wnt signaling in vitro. ZO-1 was associated with centrioles in interphase cells and mitotic spindle poles during division. In the absence of ZO-1, mitotic spindles failed to correctly orient, resulting in mitotic catastrophe and abortive proliferation. ZO-1 is, therefore, critical for up-regulation of epithelial proliferation and successful completion of mitosis. ZO-1 makes critical, tight junction–independent contributions to Wnt signaling and mitotic spindle orientation. As a result, ZO-1 is essential for mucosal repair. We speculate that ZO-1 down-regulation may be one cause of ineffective mucosal healing in patients with IBD. [Display omitted] Down-regulation of the tight junction protein ZO-1 in disease causes only mild increases in tight junction permeability but profoundly impairs mucosal healing.