Zhong Shi-Xun, Hu Guo-Hua, Liu Zhao-Hua
Department of Otolaryngology, The First Affiliated Hospital, Chongqing Medical University.
Folia Histochem Cytobiol. 2014;52(2):144-8. doi: 10.5603/FHC.2014.0010.
It has been demonstrated that the epithelial sodium channel (ENaC) may play critical roles in (re)absorbing Na+ from apical plasma membrane in various tissues and cells. Moreover, the serum glucocorticoid-inducible kinase 1 (SGK1) and the ubiquitin-protein ligase neural precursor cell-expressed, developmentally downregulated isoforms Nedd4 are involved in ENaC regulation in response to hormones such as aldosterone, vasopressin and insulin. The aim of the study was to investigate the cellular localizations of ENaC subunits, SGK1, and Nedd4 isoforms in the cochlea of guinea pig. Ten adult guinea pigs were sacrificed and their cochleas were collected. The expression patterns of ENaC subunits, SGK1 and Nedd4-2 isoforms in the guinea pig cochlea were studied by immunohistochemistry with the specific polyclonal rabbit antibodies against rat α-, β- and γ-ENaC, SGK1, Nedd4-1/2 and Nedd4-2. The results showed that all these proteins were extensively expressed in various regions of the cochlea. They were found in the spiral ligament, organ of Corti, spiral limbus, spiral ganglion and Reissner's membrane with different staining patterns. The results indicated that a Na+ transport system may exist in the cochlea of guinea pig consisting of ENaC, SGK1 and Nedd4, which may work in concert to transport Na+ and to maintain homeostasis in inner ear as it does in other epithelia.
业已证明，上皮钠通道（ENaC）在多种组织和细胞的顶端质膜对Na⁺的（再）吸收过程中可能发挥关键作用。此外，血清糖皮质激素诱导激酶1（SGK1）和泛素蛋白连接酶神经前体细胞表达、发育下调的亚型Nedd4参与了ENaC对醛固酮、血管加压素和胰岛素等激素的响应调节。本研究的目的是探究ENaC亚基、SGK1和Nedd4亚型在豚鼠耳蜗中的细胞定位。处死10只成年豚鼠并收集其耳蜗。采用针对大鼠α-、β-和γ-ENaC、SGK1、Nedd4-1/2和Nedd4-2的特异性兔多克隆抗体，通过免疫组织化学法研究豚鼠耳蜗中ENaC亚基、SGK1和Nedd4-2亚型的表达模式。结果显示，所有这些蛋白均在耳蜗的各个区域广泛表达。它们在螺旋韧带、柯蒂氏器、螺旋缘、螺旋神经节和瑞氏膜中被发现，且具有不同的染色模式。结果表明，豚鼠耳蜗中可能存在一个由ENaC、SGK1和Nedd4组成的Na⁺转运系统，该系统可能协同工作以转运Na⁺并像在其他上皮组织中一样维持内耳的内环境稳定。
