Regulation of epithelial-cells renewal by basement membrane protein composition and stiffness during gut homeostasis

ended

The intestinal epithelium forms a tight barrier against pathogens and toxins while simultaneously absorbing ions and nutrients. It is the fastest self-renewing tissue in the body, as over 3-5 days, a complete turnover of epithelial cells is achieved. Homeostasis is maintained by tight coordination between epithelial cell proliferation, differentiation, migration, and extrusion. Epithelial cells adhere and migrate on the basement membrane, a unique, sheet-like extracellular matrix that separates epithelial cells from the underlying mesenchyme. Composed primarily of laminins and type-IV collagen, the basement membrane provides structural support, promotes cell adhesion and polarity, and serves as a mechanical and biochemical signaling hub. Although great advances have been made in identifying morphogenetic regulators of epithelial-cell renewal, spatial regulators that limit proliferating cells to the crypt or guide cell migration towards the villus tip are still missing. Interestingly, basement membrane protein composition varies across the crypt-villus axis, which could also affect its stiffness. However, whether these variations play a role in regulating epithelial cell renewal has not been addressed. The overarching hypothesis of ReGutBM is that basement membrane protein composition and / or stiffness define specific zones that promote cell proliferation or cell death, and provide cues for directional migration of epithelial cells in gut homeostasis. Using ex-vivo tissue cultures and in-vivo mouse models, I will characterize the basement membrane protein composition and stiffness. Using 2D intestinal organoid cultures, I will decouple the regulatory impact of tissue stiffness and protein identity on epithelial cell renewal, and identify the molecular mechanism which facilitates BM-epithelia crosstalk during gut homeostasis.