title: Expression of ENaC, SGK1 and Nedd4 isoforms in the cochlea of guinea pig.
abstract: 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.
authors.affiliation: Department of Otolaryngology, The First Affiliated Hospital, Chongqing Medical University. zhongsx@sohu.com.
authors.forename: Shi-Xun
authors.initials: SX
authors.lastname: Zhong
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Hu
authors.forename: Zhao-Hua
authors.initials: ZH
authors.lastname: Liu
mesh_terms: D000818:Animals; D003051:Cochlea / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D053503:Epithelial Sodium Channels / Q000235:genetics / Q000378:metabolism*; D006168:Guinea Pigs; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D000075702:Nedd4 Ubiquitin Protein Ligases; D009928:Organ Specificity; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D053503:Epithelial Sodium Channels; D017874:Immediate-Early Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D044767:Ubiquitin-Protein Ligases; D000099184:Serum-Glucocorticoid Regulated Kinases; C000618479:NEDD4L protein, rat; C000618484:Nedd4 protein, rat