Keratins regulate colonic epithelial cell differentiation through the Notch1 signalling pathway

Area of Science:

• Cell Biology
• Gastroenterology
• Molecular Biology

Background:

• Keratins (K) provide mechanical support to epithelial tissues.
• Keratin 8 (K8)-knockout mice exhibit colonic hyperproliferation and colitis.
• The role of K8 in intestinal cell differentiation was previously unknown.

Purpose of the Study:

• To investigate the role of K8 in colonic epithelial cell differentiation.
• To determine the relationship between K8 and Notch1 signaling pathways.
• To elucidate the mechanisms underlying K8-deficiency-induced colonic hyperproliferation.

Main Methods:

• Co-localization and interaction studies using proximity ligation and immunoprecipitation assays.
• Analysis of Notch1 signaling components (FLN, NICD) and target gene expression in K8-knockout models.
• CRISPR/Cas9-mediated re-expression of K8/K18 in Caco-2 cells.
• In vivo studies in K8-knockout mice to assess cell differentiation and proliferation.

Main Results:

• K8 and Notch1 co-localize and interact in colonic epithelial cells.
• K8 and K18 enhance Notch1 protein levels and activity in a dose-dependent manner.
• K8 deletion leads to reduced Notch1 activity, a shift in cell differentiation towards goblet and enteroendocrine phenotypes, and increased transit amplifying progenitor cells.

Conclusions:

• K8 interacts with Notch1 and regulates its signaling activity in the colonic epithelium.
• K8 plays a crucial role in maintaining normal intestinal cell differentiation and controlling progenitor cell proliferation.
• Dysregulation of K8-Notch1 interaction contributes to colonic hyperproliferation and altered cell fate.