Deciphering how directional cues are relayed into polarized collective cell migration

The University of Chicago received a $151,040 Project Grant award from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) under the Diabetes, Digestive, and Kidney Diseases Extramural Research program (CFDA 93.847), effective December 11, 2025, with completion scheduled for November 30, 2028. The award funds fundamental biomedical research investigating how epithelial cell collectives sense and respond to directional cues during collective cell migration—a process relevant to tissue development, organ maintenance, and disease mechanisms including cancer metastasis. The research utilizes the zebrafish pronephros (embryonic kidney) as a model system to elucidate how directional information from luminal fluid flow is translated into polarized migration behaviors through polarity protein modules.

The principal deliverables from this research project include scientific findings on the role of the FAT1A/LARA/LARB protein complex in flow-dependent orientation of migratory protrusions, mechanistic insights into ciliary flow sensing in pronephric epithelium, and experimental validation of polarity-dependent collective migration mechanisms through live-imaging studies of wildtype and genetically modified zebrafish embryos. The funded research addresses fundamental knowledge gaps in vertebrate epithelial collective migration and is expected to advance understanding of morphogenetic processes with implications for kidney disease and organ development, consistent with NIDDK's mission to support biomedical research on mechanisms underlying kidney and digestive system diseases.

Abstract

Cells within epithelial sheets undergo collective cell migration during a variety of processes including tissue morphogenesis, organ homeostasis, and cancer metastasis. However, we lack a clear understanding of how epithelial collectives sense directional cues and translate them into polarized movements, particularly in vertebrates. Through the proposed project, i will establish the zebrafish pronephros (embryonic kidney) as a tractable, in vivo model of epithelial collective cell migration. During development, the epithelial cells of the pronephric duct undergo a collective cell migration towards the anterior of the embryo, driving morphogenesis of the proximal tubule. This migration is powered by the extension and retraction of migratory protrusions at the basal cell surface. Lumenal fluid flow has been identified as the directional CUE that dictates migration orientation: pronephric epithelial cells migrate against flow. Therefore, the pronephric epithelium is an ideal yet underutilized system to study how cells sense and relay directional information during collective migration, as both the upstream polarizing CUE (fluid flow) and the downstream readout (anterior migration) are known. Collective migration is often regulated by polarity modules that coordinate cytoskeletal behaviors. I hypothesize that the zebrafish FAT1A/lara/larb proteins function as a migratory polarity module that orients pronephric protrusions in a flow-dependent manner. In aim 1, i will test this hypothesis through live-imaging of migration in wildtype and polarity-mutant embryos. By mechanically altering pronephric flow in embryos expressing tagged polarity proteins, i will determine if the FAT1A/lara/larb polarity module localizes in a flow-dependent manner. Cilia have long been speculated to function as flow sensors in the pronephric epithelium. I hypothesize that mechanosensitive sensory cilia detect flow via the PKD2/calcium signaling pathway. In aim 2, i will test this hypothesis by performing live calcium imaging to ascertain if there is a population of cilia exhibiting flow- responsive calcium signaling. Engineering of a ciliary-trafficking PKD2-mutant will reveal if ciliary PKD2 is required for migration. Together, the proposed experiments will shed light on how epithelial cells translate directional cues into polarized migration, advancing our understanding of kidney development. Moreover, through completion of these aims, i will learn essential skills in zebrafish genetics, molecular cloning, and live-imaging that will be key to the success of my future independent research lab.