Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045.
Center for C. elegans Anatomy, Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461.
Genetics. 2018 Oct;210(2):637-652. doi: 10.1534/genetics.118.301078. Epub 2018 Jun 26.
The excretory canals of are a model for understanding the maintenance of apical morphology in narrow single-celled tubes. Light and electron microscopy shows that mutants in start to form canals normally, but these swell to develop large fluid-filled cysts that lack a complete terminal web at the apical surface, and accumulate filamentous material in the canal lumen. Here, whole-genome sequencing and gene rescue show that encodes intermediate filament protein IFC-2 EXC-2/IFC-2 protein, fluorescently tagged via clustered regularly interspaced short palindromic repeats/Cas9, is located at the apical surface of the canals independently of other intermediate filament proteins. EXC-2 is also located in several other tissues, though the tagged isoforms are not seen in the larger intestinal tube. Tagged EXC-2 binds via pulldown to intermediate filament protein IFA-4, which is also shown to line the canal apical surface. Overexpression of either protein results in narrow but shortened canals. These results are consistent with a model whereby three intermediate filaments in the canals-EXC-2, IFA-4, and IFB-1-restrain swelling of narrow tubules in concert with actin filaments that guide the extension and direction of tubule outgrowth, while allowing the tube to bend as the animal moves.
是一种模型生物，其排泄道可用于研究在狭窄的单细胞管中维持顶端形态的机制。光镜和电镜显示，在 突变体中，排泄道开始正常形成，但随后会扩张，形成充满液体的大囊肿，顶端表面缺乏完整的终末网，管腔中积累丝状物质。全基因组测序和基因拯救表明， 编码中间丝蛋白 IFC-2（EXC-2/IFC-2 蛋白）。通过成簇规律间隔短回文重复序列/ Cas9 系统对其进行荧光标记后，发现其定位于排泄道的顶端表面，与其他中间丝蛋白无关。EXC-2 还存在于其他几种组织中，但在较大的肠管中未观察到标记的同工型。标记的 EXC-2 通过下拉与中间丝蛋白 IFA-4 结合，IFA-4 也被证明排列在排泄道的顶端表面。两种蛋白的过表达都会导致排泄道变窄但缩短。这些结果表明，在排泄道中存在三种中间丝蛋白（EXC-2、IFA-4 和 IFB-1），它们与肌动蛋白丝一起协同限制狭窄管的扩张，从而引导管的延伸和生长方向，同时允许管在动物移动时弯曲。
