Epithelial signals that influence the form and function of somatosensory neurons in Drosophila

Abstract

Cell-cell interaction plays an important role in regulating cell morphology and function. In the peripheral nervous system, somatosensory neurons innervate our skin and interact with the epidermis to help us sense the world. However, the cellular interactions between epidermis and neurons and possible mechanisms by which the skin controls neuron growth and function are largely unexplored. This gap in our knowledge limits our ability to treat somatosensory neuron disease, which has a major impact on the quality of human lives. In our lab, we use Drosophila Class IV da neurons as a model system to study the interaction between somatosensory neurons and epidermis. Firstly, we identified signals derived from epithelial cells that regulate the coordinated growth between the Class IV sensory neurons and body wall epithelial cells during Drosophila larva development. We found epithelial microRNA bantam regulates a special type of cell cycle in body wall epithelial cells, which then mediates dendrite growth through regulating a close interaction between dendrites and body wall epithelial cells. This close dendrite-epithelial interaction, where dendrites are ensheathed by epithelial cells, is a conserved structure across species. We identified and characterized the molecular components on epithelial membrane specialized domains that are associated with dendritic ensheathment by using the GAL4-UAS expression screen and an expansion microscopy imaging technique that we adapted specifically for this purpose. We found this actin rich structure on the epithelial cell membrane is regulated by epithelial endocytosis. Interestingly, this epithelial membrane specialized domain can facilitate and stabilize dendritic ensheathment which is induced by dendrite derived signals. Finally, we found that dendritic ensheathment also plays very important functional roles by mediating the Class IV da neuron nociception.