EXPRESSION OF ALPHA-SUBUNIT AND BETA-SUBUNIT ISOFORMS OF NA,K-ATPASE IN THE MOUSE INNER-EAR AND CHANGES WITH MUTATIONS AT THE W-V OR SL(D) LOCI
EXPRESSION OF ALPHA-SUBUNIT AND BETA-SUBUNIT ISOFORMS OF NA,K-ATPASE IN THE MOUSE INNER-EAR AND CHANGES WITH MUTATIONS AT THE W-V OR SL(D) LOCI
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DOI：
10.1016/0378-5955(94)90045-0
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发表时间：
1994-07-01
期刊：
影响因子：
2.8
通讯作者：
STEEL, KP
中科院分区：
文献类型：
--
作者：
SCHULTE, BA;STEEL, KP
在有活力的显性斑点位点（W-v）和钢-迪基位点（Sl(d)）纯合突变的小鼠表现出类似的表型，包括耳聋。听觉功能障碍是由于血管纹不能正常发育和产生高正耳蜗电位引起的。由于试验功能是由Na， k - atp酶驱动的，因此通过抗血清免疫染色研究了其在W-v/W-v和Sl(d)/Sl(d)小鼠及其野生型仔鼠内耳中的表达。来自两种不同遗传背景的野生型小鼠在内耳运输细胞中显示出相同的亚基亚型分布。几种上皮细胞类型共表达α 1和β 1亚基。前庭暗细胞对β - 1无反应性，但表达丰富的β - 2，而审判边缘细胞对两种β亚型都有强烈的染色。突变型小鼠与野生型小鼠之间的唯一定性差异是突变型小鼠纹边缘细胞中缺乏β 1亚基。然而，这种差异不太可能解释突变体不能产生高EP的原因，因为β 1亚基不存在于EP值正常的大鼠或沙鼠的血管纹中。正常小鼠侧壁纤维细胞中Na，K- atp酶的免疫染色较强，突变小鼠的免疫反应性降低，这支持了这些战略性转运纤维细胞积极吸收通过雷氏膜泄漏到前庭鳞片或从毛细胞和神经流出到中耳膜的K+的概念。进一步推测，被吸收的K+通常通过纤维细胞与基底细胞和中间细胞之间的间隙连接沿其浓度梯度被虹吸到胃内间隙，然后通过边缘细胞再循环回到内淋巴。因此，突变体不能产生阳性EP可以解释为缺乏中间细胞，中间细胞可能形成将K+从淋巴管周围转移到胃内腔室的最后一环。
Mice homozygous for mutations at the viable dominant spotting (W-v) and Steel-dickie (Sl(d)) loci exhibit a similar phenotype which includes deafness. The auditory dysfunction derives from failure of the stria vascularis to develop normally and to generate a high positive endocochlear potential (EP). Because strial function is driven by Na,K-ATPase its expression was investigated in inner ears of W-v/W-v and Sl(d)/Sl(d) mice and their wild-type littermates by immunostaining with antisera against four of the enzyme's subunit isoforms. Wild-type mice from two different genetic backgrounds showed an identical distribution of subunit isoforms among inner ear transport cells. Several epithelial cell types coexpressed the alpha 1 and beta 1 subunits. Vestibular dark cells showed no reactivity for beta 1 but expressed abundant beta 2, whereas, strial marginal cells stained strongly for both beta isoforms. The only qualitative difference between mutant and wild-type mice was the absence of beta 1 subunit in marginal cells of the mutant's stria. However, it is unlikely that this difference accounts for failure of mutants to generate a high EP because the beta 1 subunit is not present in the stria vascularis of either rats or gerbils with normal EP values. Strong immunostaining for Na,K-ATPase in lateral wall fibrocytes of normal mice along with diminished immunoreactivity in the mutants supports the concept that these strategically located transport fibrocytes actively resorb K+ leaked across Reissner's membrane into scala vestibuli or effluxed from hair cells and nerves into scala tympani. It is further speculated that the resorbed K+ normally is siphoned down its concentration gradient into the intrastrial space through gap junctions between fibrocytes and strial basal and intermediate cells where it is recycled back to endolymph via marginal cells. Thus, failure of mutants to generate a positive EP could be explained by the absence of intermediate cells which may form the final link in the conduit for moving K+ from perilymph to the intrastrial compartment.