Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA.
Université de Rennes 1, Plateforme microscopie électronique, 35043 Rennes, France.
Development. 2019 Feb 20;146(4):dev171124. doi: 10.1242/dev.171124.
To sense the outside world, some neurons protrude across epithelia, the cellular barriers that line every surface of our bodies. To study the morphogenesis of such neurons, we examined the amphid, in which dendrites protrude through a glial channel at the nose. During development, amphid dendrites extend by attaching to the nose via DYF-7, a type of protein typically found in epithelial apical ECM. Here, we show that amphid neurons and glia exhibit epithelial properties, including tight junctions and apical-basal polarity, and develop in a manner resembling other epithelia. We find that DYF-7 is a fibril-forming apical ECM component that promotes formation of the tube-shaped glial channel, reminiscent of roles for apical ECM in other narrow epithelial tubes. We also identify a requirement for FRM-2, a homolog of EPBL15/moe/Yurt that promotes epithelial integrity in other systems. Finally, we show that other environmentally exposed neurons share a requirement for DYF-7. Together, our results suggest that these neurons and glia can be viewed as part of an epithelium continuous with the skin, and are shaped by mechanisms shared with other epithelia.
为了感知外部世界，一些神经元会穿过上皮细胞（epithelia）向外突出，上皮细胞是构成我们身体每一面的细胞屏障。为了研究这些神经元的形态发生，我们研究了触角（amphid），其树突通过位于鼻子处的一个神经胶质通道向外突出。在发育过程中，触角树突通过与鼻子上的 DYF-7 蛋白结合而延伸，这种蛋白通常存在于上皮细胞的顶端细胞外基质（ECM）中。在这里，我们发现触角神经元和神经胶质表现出上皮细胞的特性，包括紧密连接和顶端-基底极性，并以类似于其他上皮细胞的方式发育。我们发现 DYF-7 是一种形成纤维的顶端 ECM 成分，可促进管状神经胶质通道的形成，这让人联想到顶端 ECM 在其他狭窄的上皮管中的作用。我们还发现 FRM-2（一种在其他系统中促进上皮完整性的 EPBL15/moe/Yurt 同源物）的作用对于这种发育是必需的。最后，我们发现其他暴露于环境中的神经元也需要 DYF-7。总之，我们的结果表明，这些神经元和神经胶质可以被视为与皮肤连续的上皮的一部分，并且其形态由与其他上皮细胞共享的机制塑造。
