Geometric contributions to the morphogenesis of tissues into correct organ shapes - Project Summary A daunting aspect of development is the orchestration of precise organ formation, guided by the transformative process of tissue morphogenesis. Errors in this process result in congenital malformations, for which treatments by tissue reconstruction and organ engineering are only as effective as our understanding of tissue development in vivo. Our current view of morphogenesis is anchored in the roles of developmental genes, but we have come to understand that the spatial context where a gene functions also matters. This is governed by tissue material properties and geometry. Recent significant progress has revealed the in vivo functions of material properties. The geometry of a developing tissue has historically eluded functional in vivo research due to a lack of direct tests, though intuitively tissue geometry likely constrains and feeds back on genetics and material properties in vivo. With the zebrafish embryonic inner ear as a model system, I will directly tune geometry to uncover how geometry regulates morphogenesis. In this proposed study I will investigate how geometry contributes to tissue morphogenesis in the zebrafish inner ear. In Aim 1, I will explore how the geometry of stress distributed across the tissue impacts the resulting tissue shape. I will first infer cell stress by fitting a model with tissue-wide strain rates calculated from changes in 3D cell shapes. I will then map inferred stress distribution with higher resolution using transcriptional identities revealed through spatial transcriptomics. This will be a novel application of spatial transcriptomics across time in a developing tissue and will also reveal the stress-fate relationship on a tissue-wide scale over time. Finally, I will then test how geometric distribution of stress regulates morphogenesis through perturbation of tissue- wide stress distribution. In Aim 2, I will study how the initial geometry of the tissue itself contributes to successful morphogenesis. I will first quantify changes in morphology and surface curvature during healthy inner ear development. This will inform a physical vertex model of the tissue’s surface, with which I will make predictions about tissue geometry’s contributions to morphogenesis. Finally, I will directly perturb initial tissue geometry and measure how this impacts the progression of morphogenesis and the resulting organ shape. These perturbations will test the biophysical accuracy of my surface vertex model, highlighting features that recapitulate development, from which we will learn and build our intuition of the system. The results of perturbations from both aims will independently reveal in vivo functions of geometry in morphogenesis. Successful completion of this study will uncover fundamental aspects of inner ear development, informing disease etiology of congenital syndromes, particularly those that exhibit inner ear, renal, and cardiovascular comorbidities. By quantitatively investigating geometry’s contributions to morphogenesis in vivo, my proposed work will uncover specific geometric parameters that influence proper organ shape, which will move the field of tissue engineering forward in exciting and transformative ways.
