Epitope-tag-mediated synaptogenic activity in an engineered neurexin-10 lacking the binding interface with neuroligin-1

Clustering of neurexin-10 occurs through the formation of a trans-cellular complex with neuroligin-1, which promotes the generation of presynapse. While the extracellular region of neurexin-10 functions to constitute the heterophilic binding interface with neuroligin-1, it has remained unclear whether the region could also play any key role in exerting the intracellular signaling for presynaptic differentiation. In this study, we generated neurexin-10 lacking the binding site to neuroligin-1 and with a FLAG epitope at the N-terminus, and examined its activity in cultured neurons. The engineered protein still exhibited robust synaptogenic activities upon the epitope-mediated clustering, indicating that the region for complex formation and that for transmitting presynapse differentiation signals are structurally inde-pendent of each other. Using a fluorescence protein as an epitope, synaptogenesis was also induced by a gene-codable nanobody. The finding opens possibilities of neurexin-10 as a platform for developing various molecular tools which may allow, for example, precise modifications of neural wirings under genetic control.(c) 2023 Elsevier Inc. All rights reserved.