Ecdysone Orchestrates Notch and Broad Symphony to Craft Epithelial Cell Shape Change

Morphogenesis in the metazoans relies on cell shape transformations that forms an integral component of organ development, form generation and maintenance of tissue homeostasis. Nevertheless, a comprehensive grasp of how the epithelial morphogenesis is modulated in the metazoans remain still elusive. The Steroid hormones play a pivotal role in morphogenesis spanning several organs including the gonads, urogenital tracts, and mammary glands. Employing the Drosophila oogenesis model, we investigated the the role of steroid hormone receptor, Ecdysone receptor (EcR) involvement in transforming anterior epithelial follicle cells (AFCs) from cuboidal to squamous shape. Consistent with the fact that the activity of EcR in the AFCs coincides with the timing of cuboidal-to-squamous shape transition, we found that depletion of EcR function impedes the shape transformation of AFCs. We report that EcR doesnt impair the follicle cell fate, but impedes the morphological change by restricting the remodelling of lateral and adherens junctions. Employing the classical genetic tools and immnohistochemistry, we show that EcR limits the Notch-Broad axis to facilitate alteration of the shape of AFCs. Our study suggests a mechanistic model where Ecdysone signalling, via the Notch pathway, finetunes the activity of non-muscle myosin heavy chain zipper, prompting AFC shape transition. In sum, our work illuminates how Ecdysone signalling orchestrates epithelial follicle cell morphogenesis during metazoan development.