LAUSR

except the cytoplasmic tail. Neuronal-specific Nrg180 regulates dendrite growth, while epidermal Nrg167 is likely involved in cell-cell adhesion. Here, we showed that, in addition to cell-cell junctional expression, epidermal Nrg167 also localizes to linear segmental structures aligned parallel to da dendrites. This structure, named dendritic foundation, play roles in stabilizing dendrites during growth, and in preventing unwanted dendrite-dendrite interaction. Epidermal Nrg167 supports dendrite formation as overexpression induced ectopic dendrites, while depletion reduced dendritic branches. Interestingly, epidermal Nrg167 and neuronal Nrg180 showed mutual stabilization by each other, suggesting a heterophillic interaction between neuronal Nrg180 and epidermalNrg167.We further show that epidermal Nrg167 induces dendrite enwrap inside epidermal cells and prevents heteroneuronal dendrite bundling, indicating that epidermal Nrg167 accurately positions dendrites in the 3D space. Finally, we found that dendrite bundling involves homophillic interaction between dendritic Nrg180, and is prevented by endocytosis of Nrg180 in dendrites.