NEUROMUSCULAR TARGET RECOGNITION BY A HEMOPHILIC INTERACTION OF CONNECTIN CELL-ADHESION MOLECULES IN DROSOPHILA

Drosophila Connectin (CON) is a cell surface protein of the leucine-ri ch repeat family. During the formation of neuromuscular connectivity, CON is expressed on the surface of a subset of embryonic muscles and o n the growth cones and axons of the motoneurons that innervate these m uscles, including primarily SNa motoneurons and their synaptic targets (lateral muscles). In vitro, CON can mediate hemophilic cell adhesion . In this study, we generated transgenic lines that ectopically expres sed CON on all muscles. In the transformant embryos and larvae, SNa mo toneurons often inappropriately innervated a neighboring non-target mu scle (muscle 12) that ectopically expressed CON. Furthermore, the ecto pic synapse formation was dependent on the endogenous CON expression o n the SNa motoneurons. These results show that CON can function as an attractive and hemophilic target recognition molecule in vivo.