Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA.
Dev Biol. 2021 Oct;478:1-12. doi: 10.1016/j.ydbio.2021.06.007. Epub 2021 Jun 18.
Dorsal root ganglion (DRG) neurons are the predominant cell type that innervates the vertebrate skin. They are typically described as pseudounipolar cells that have central and peripheral axons branching from a single root exiting the cell body. The peripheral axon travels within a nerve to the skin, where free sensory endings can emerge and branch into an arbor that receives and integrates information. In some immature vertebrates, DRG neurons are preceded by Rohon-Beard (RB) neurons. While the sensory endings of RB and DRG neurons function like dendrites, we use live imaging in zebrafish to show that they have axonal plus-end-out microtubule polarity at all stages of maturity. Moreover, we show both cell types have central and peripheral axons with plus-end-out polarity. Surprisingly, in DRG neurons these emerge separately from the cell body, and most cells never acquire the signature pseudounipolar morphology. Like another recently characterized cell type that has multiple plus-end-out neurites, ganglion cells in Nematostella, RB and DRG neurons maintain a somatic microtubule organizing center even when mature. In summary, we characterize key cellular and subcellular features of vertebrate sensory neurons as a foundation for understanding their function and maintenance.
背根神经节 (DRG) 神经元是支配脊椎动物皮肤的主要细胞类型。它们通常被描述为具有中央和外周轴突的假单极细胞，这些轴突从单个根分叉离开细胞体。外周轴突沿着神经到达皮肤，在那里游离感觉末梢可以出现并分支成一个接收和整合信息的树突状分支。在一些未成熟的脊椎动物中，DRG 神经元之前是 Rohon-Beard (RB) 神经元。虽然 RB 和 DRG 神经元的感觉末梢的功能类似于树突，但我们使用斑马鱼的活体成像显示，它们在成熟的各个阶段都具有轴突正端向外的微管极性。此外，我们还显示这两种细胞类型都具有中央和外周轴突，具有正端向外的极性。令人惊讶的是，在 DRG 神经元中，这些轴突从细胞体中单独出现，而且大多数细胞从未获得标志性的假单极形态。与另一种最近被描述的具有多个正端向外神经突的细胞类型一样，海葵中的神经节细胞和 RB 和 DRG 神经元在成熟时仍然维持着一个体微管组织中心。总之，我们描述了脊椎动物感觉神经元的关键细胞和亚细胞特征，为理解它们的功能和维持提供了基础。
