Investigating a role for Wnt-associated planar polarity in collective migration of human intestinal epithelium

Abstract. The intestinal epithelium (IE) lines the entire inner surface of the intestine, handling all of the body’s nutrient and fluid uptake while simultaneously serving as a barrier to toxic luminal contents and pathogens. To combat the damage human intestinal epithelial cells (hIECs) accumulate during homeostasis, cells on the villi (primary absorptive surfaces) are constantly replaced. Dedicated intestinal stem cells (hISCs) in crypts proliferate continuously to generate a steady stream of progenitor cells that collectively migrate towards the villi in one of the most expansive examples of collective cell migration in the adult body. Following IEC injury or loss, nearby IECs undergo a rapid collective migration called restitution to quickly repair the damage. Restitution driven by collective migration is an essential cellular process to preserve the barrier against luminal contents. Despite the importance of collective cell migration to intestinal function, little is known about how hIECs coordinate this process. The WNT-associatedPlanar Cell Polarity (WPCP) pathway, and in particular the cell surface protein VANGL2, has been increasingly implicated as a major player in the coordination of collective cell migration, but research is hampered due to a major deficit of physiologically relevant model systems for studying WPCP in higher organisms. Observations from my preliminary data indicate that: 1) sporadic overexpression of VANGL2 is sufficient to strongly impair collective migration, 2) VANGL2 is upregulated at the leading edge of an epithelial wound in scratchassays, and 3) a protein gradient of VANGL2 exists along the in vivo crypt-villus axis. Together these observations led me to hypothesize that the IE utilizes the WPCP pathway to coordinate collective cell migration. I will test this hypothesis using two aims. Aim 1 will establish a mechanistic role for WPCP in homeostatic migration, while Aim 2 will establish its role in wound healing. Both aims will use novel inducible genetic models of WPCP pathway perturbations to generate primary data. This will be used to train a computational reaction-diffusion model of WPCP polarity to decipher how local WPCP feedback can so strongly impact collective migration of large tissue regions. This study will fill critical technical and knowledge gaps by generating new culture models with primary human cells, uncovering novel mechanisms of how the hIE controls collective migration, and building novel computational models for studying collective migration and WPCP. My findings will be significant as VANGL2 and WPCP ligands are increasingly implicated in diverse health conditions including developmental defects, neurological and kidney disease, skeletal muscle and biliary duct regeneration, cancer metastasis, and chronic colitis.