Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL 60612, USA.
Proc Natl Acad Sci U S A. 2012 Mar 20;109(12):4473-8. doi: 10.1073/pnas.1101003109. Epub 2012 Mar 6.
The striated organelle (SO), a cytoskeletal structure located in the apical region of cochlear and vestibular hair cells, consists of alternating, cross-linked, thick and thin filamentous bundles. In the vestibular periphery, the SO is well developed in both type I and type II hair cells. We studied the 3D structure of the SO with intermediate-voltage electron microscopy and electron microscope tomography. We also used antibodies to α-2 spectrin, one protein component, to trace development of the SO in vestibular hair cells over the first postnatal week. In type I cells, the SO forms an inverted open-ended cone attached to the cell membrane along both its upper and lower circumferences and separated from the cuticular plate by a dense cluster of exceptionally large mitochondria. In addition to contacts with the membrane and adjacent mitochondria, the SO is connected both directly and indirectly, via microtubules, to some stereociliary rootlets. The overall architecture of the apical region in type I hair cells--a striated structure restricting a cluster of large mitochondria between its filaments, the cuticular plate, and plasma membrane--suggests that the SO might serve two functions: to maintain hair-cell shape and to alter transduction by changing the geometry and mechanical properties of hair bundles.
纹状细胞器 (SO) 是一种位于耳蜗和前庭毛细胞顶部区域的细胞骨架结构，由交替的、交联的、粗和细的丝状束组成。在前庭外周，SO 在 I 型和 II 型毛细胞中都很发达。我们使用中等电压电子显微镜和电子显微镜断层扫描技术研究了 SO 的三维结构。我们还使用了一种α-2 spectrin 的抗体，这是一种蛋白质成分，来追踪前庭毛细胞中 SO 在出生后第一周的发育情况。在 I 型细胞中，SO 形成一个倒置的开口锥形结构，沿着细胞膜的上下两个圆周附着在细胞膜上，与角质板由一群异常大的线粒体隔开。除了与膜和相邻的线粒体接触外，SO 通过微管与一些前庭纤毛根直接和间接相连。I 型毛细胞顶部区域的总体结构——一种由丝状结构限制的条纹状结构，将一群大的线粒体夹在中间，还有角质板和质膜——表明 SO 可能具有两种功能：维持毛细胞的形状，并通过改变毛束的几何形状和机械特性来改变转导。
