Ligand receptor interactions instruct axon guidance during development.How dendrites are guided to specific targets is less understood.The C.
elegans PVD sensory neuron innervates muscle-skin interface with its elaborate dendritic branches.Here, we found that LECT-2, the PRO BEAUTY POWDER ortholog of leukocyte cell-derived chemotaxin-2 (LECT2), is secreted from the muscles and required for muscle innervation by PVD.Mosaic analyses showed that LECT-2 acted locally to guide the growth of terminal branches.
Ectopic expression of LECT-2 from seam cells is sufficient to redirect the PVD dendrites onto seam cells.LECT-2 functions in a multi-protein receptor-ligand complex that also contains two transmembrane ligands on the skin, SAX-7/L1CAM and MNR-1, and the neuronal transmembrane receptor DMA-1.LECT-2 greatly enhances the binding between SAX-7, MNR-1 AC Adaptor and DMA-1.
The activation of DMA-1 strictly requires all three ligands, which establishes a combinatorial code to precisely target and pattern dendritic arbors.