Synaptic target recognition at Drosophila neuromuscular junctions

Every synaptogenesis begins with "synaptic target recognition," a cell-cell recognition event in which a neuron and its target stably adhere. Despite its importance in developing nervous systems, synaptic target recognition has been difficult to study in complex systems. The relatively simple and genetically accessible Drosophila NMJ model system provides a repertoire of target recognition cues. We describe how these molecules control the targeting of specific growth cones in either a positive (synaptogenic) or negative (anti-synaptogenic) manner. We also propose two alternate signaling paradigms to explain how these initial cell recognition events are coupled to the intracellular signaling pathways that begin the process of synapse maturation.