Fasciclin II and Beaten path modulate intercellular adhesion in Drosophila larval visual organ development.

Previous studies demonstrated that Fasciclin II and Beaten path are necessary for regulating cell adhesion events that are important for motoneuron development in Drosophila. We observe that the cell adhesion molecule Fasciclin II and the secreted anti-adhesion molecule Beaten path have additional critical roles in the development of at least one set of sensory organs, the larval visual organs. Taken together, phenotypic analysis, genetic interactions, expression studies and rescue experiments suggest that, in normal development, secretion of Beaten path by cells of the optic lobes allows the Fasciclin II-expressing larval visual organ cells to detach from the optic lobes as a cohesive cell cluster. Our results also demonstrate that mechanisms guiding neuronal development may be shared between motoneurons and sensory organs, and provide evidence that titration of adhesion and anti-adhesion is critical for early steps in development of the larval visual system.