Department of Biology, Duke University, Durham, NC, United States of America.
Department of Statistical Science, Duke University, Durham, NC, United States of America.
PLoS Genet. 2018 Aug 13;14(8):e1007560. doi: 10.1371/journal.pgen.1007560. eCollection 2018 Aug.
In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe. Despite the identification of cell surface receptors regulating axon guidance, how ORN axons sort to form 50 stereotypical glomeruli remains unclear. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. DIP/Dpr profiles are dynamic during development and correlate with sensilla type lineage for some ORN classes. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli.
在果蝇中，50 类嗅觉受体神经元（ORNs）连接到触角叶中 50 个具有特异性和独特位置的神经节。尽管已经鉴定出调节轴突导向的细胞表面受体，但 ORN 轴突如何进行分类以形成 50 个典型的神经节仍然不清楚。在这里，我们表明，嗜同性细胞粘附蛋白 DIP 和 Dprs 在形成神经节时在 ORNs 中表达。许多 ORN 类表达独特的 DIP/dpr 组合，同一类的神经元表达相互作用的伴侣，表明在 ORN 轴突的特异性自我粘附中起作用。对 DIP/Dpr 表达的分析表明，靶向相邻神经节的 ORNs 具有不同的组合，而具有非常相似 DIP/Dpr 组合的 ORNs 可以投射到触角叶中遥远的神经节。DIP/Dpr 谱在发育过程中是动态的，并且与某些 ORN 类的感觉器类型谱系相关。DIP/dpr 基因功能的破坏会导致 ORN 轴突和神经节定位的局部投射缺陷，而不会改变 ORN 与靶神经元的正确匹配。我们的结果表明，通过 DIP/Dpr 组合的上下文相关差异粘附调节自我粘附并将 ORN 轴突分类到具有独特位置的神经节中。
