Recognition of pre- and postsynaptic neurons via nephrin/NEPH1 homologs is a basis for the formation of theDrosophilaretinotopic map

Abstract

SUMMARYTopographic maps, which maintain the spatial order of neurons in the order of their axonal connections, are found in many parts of the nervous system. Here, we focus on the communication between retinal axons and their postsynaptic partners, lamina neurons, in the first ganglion of the Drosophila visual system, as a model for the formation of topographic maps. Post-mitotic lamina precursor cells differentiate upon receiving Hedgehog signals delivered through newly arriving retinal axons and, before maturing to extend neurites, extend short processes toward retinal axons to create the lamina column. The lamina column provides the cellular basis for establishing stereotypic synapses between retinal axons and lamina neurons. In this study, we identified two cell-adhesion molecules: Hibris, which is expressed in post-mitotic lamina precursor cells; and Roughest, which is expressed on retinal axons. Both proteins belong to the nephrin/NEPH1 family. We provide evidence that recognition between post-mitotic lamina precursor cells and retinal axons is mediated by interactions between Hibris and Roughest. These findings revealed mechanisms by which axons of presynaptic neurons deliver signals to induce the development of postsynaptic partners at the target area. Postsynaptic partners then recognize the presynaptic axons to make ensembles, thus establishing a topographic map along the anterior/posterior axis.

Structural Analysis of the Myo1c and Neph1 Complex Provides Insight into the Intracellular Movement of Neph1

“…Although the exact function of Neph1 at the podocyte cell membrane is unclear, its role in the podocyte development is supported from the studies with Drosophila and Caenorhabditis elegans models in which it has been shown to be involved in axonal guidance and synapse development, respectively (58,59). Since Myo1c also localizes to the actin-rich periphery and plasma membrane and has been shown to be involved in regulating dynamic cellular processes, including vesicle trafficking, cell migration, cell spreading, and membrane tension (15,23,27,55,60), it is likely that the interaction between Neph1 and Myo1c contributes toward the regulation of Neph1 signaling and trafficking.…”

Podocytes: recent biomolecular developments

“…The expression of nephrin in neuronal cells is of particular interest because the nephrin orthologues in Caenorhabditis elegans (Syg-2) and Drosophila melanogaster (Hibris) are crucial players in synapse targeting and positioning (45,46), suggesting that, evolutionarily speaking, the original function of nephrin is that of a synaptic adhesion molecule.…”

Tethering Membrane Fusion: Common and Different Players in Myoblasts and at the Synapse

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