Altered polarity and expression of H+-ATPase without ultrastructural changes in kidneys of Dent's disease patients
Altered polarity and expression of H+-ATPase without ultrastructural changes in kidneys of Dent's disease patients
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DOI：
10.1046/j.1523-1755.2003.00851.x
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发表时间：
2003-04-01
影响因子：
19.6
通讯作者：
Devuyst, O
中科院分区：
文献类型：
--
作者：
Moulin, P;Igarashi, T;Devuyst, O
背景。 Dent 病是一种近端小管 (PT) 疾病，以低分子量蛋白尿 (LWMP) 为特征，可能与高钙尿症、肾钙质沉着症和肾功能衰竭有关。它是由肾氯离子通道 ClC-5 失活突变引起的，ClC-5 与 PT 细胞和 α 型闰细胞中的液泡 H+-ATP 酶共定位。对基因敲除小鼠的检查已经确定了 ClC-5 在 PT 内吞作用中的作用，但 ClC-5 突变对 H+-ATP 酶和其他质膜蛋白极性的影响仍然未知。方法。我们通过光学和电子显微镜以及免疫组织化学染色研究了 8 名因 ClC-5 失活突变而患有 Dent 病的患者的肾活检。所有患者均表现出 LMWP，肾功能范围从正常到终末期肾衰竭。结果。光学显微镜检查显示肾结构正常或肾小球硬化、肾小管去分化和萎缩以及轻度间质纤维化。在所有阶段均发现局灶性透明管型，有时钙化。电镜检查未发现PT细胞有任何超微结构异常，内吞器官明显正常。然而，免疫组织化学研究表明，PT 细胞中 H+-ATP 酶极性一致反转为基底外侧分布，与其在正常肾脏中的顶端位置形成鲜明对比。这种极性反转是 H+-ATP 酶特有的，不影响氨肽酶、巨蛋白和 Na+/K+-ATP 酶的分布。此外，α型闰细胞中不存在顶端H+-ATP酶表达。结论。 ClC-5 突变与 H+-ATPase 的极性和表达的改变有关，但与 PT 细胞的超微结构改变无关。这些发现有助于进一步了解 ClC-5 的作用和 Dent 病的病理生理学。
Background. Dent's disease is a proximal tubule (PT) disorder characterized by low-molecular-weight proteinuria (LWMP) that may be associated with hypercalciuria, nephrocalcinosis, and renal failure. It is caused by inactivating mutations of the renal chloride channel ClC-5, which colocalizes with the vacuolar H+-ATPase in PT cells and alpha-type intercalated cells. Examinations of knockout mice have established the role of ClC-5 in PT endocytosis, but the consequences of ClC-5 mutations on the polarity of H+-ATPase and other plasma membrane proteins remain unknown.Methods. We have studied renal biopsies from eight patients with Dent's disease, due to inactivating ClC-5 mutations, by light and electron microscopy, and by immunohistochemical staining. All patients exhibited LMWP, and renal function ranged from normal to end-stage renal failure.Results. Light microscopy revealed either normal renal architecture or glomerulosclerosis, tubular dedifferentiation and atrophy, and mild interstitial fibrosis. Focal, hyaline casts, sometimes calcified, were identified at all stages. Electron microscopy did not reveal any ultrastructural abnormalities in PT cells, and the endocytic apparatus was apparently normal. However, immunohistochemical studies demonstrated a consistent inversion of H+-ATPase polarity in PT cells to a basolateral distribution contrasting with its apical location in the normal kidney. This inversion of polarity was specific for H+-ATPase and did not affect distribution of aminopeptidase, megalin, and Na+/K+-ATPase. Furthermore, apical H+-ATPase expression was absent in alpha-type intercalated cells.Conclusion. ClC-5 mutations are associated with modifications in the polarity and expression of H+-ATPase, but not ultrastructural alterations in PT cells. These findings help further understanding of the role of ClC-5 and the pathophysiology of Dent's disease.