Pathobiologic Mechanisms of Neurodegeneration in Osteopetrosis Derived From Structural and Functional Analysis of 14 ClC-7 Mutants
Pathobiologic Mechanisms of Neurodegeneration in Osteopetrosis Derived From Structural and Functional Analysis of 14 ClC-7 Mutants
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DOI：
10.1002/jbmr.4200
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发表时间：
2020-11-29
影响因子：
6.2
通讯作者：
Picollo，Alessandra
中科院分区：
文献类型：
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作者：
Di Zanni，Eleonora;Palagano，Eleonora;Picollo，Alessandra
ClC‐7是ClC蛋白家族的氯质子反转运蛋白。ClC‐7与其附属蛋白Ostm‐1一起定位于溶酶体和破骨细胞的皱褶边界，在骨吸收过程中，它在酸化吸收腔隙中起关键作用。小鼠基因失活导致严重的骨质疏松症、神经变性和溶酶体贮积病。人类CLCN7基因突变与多种形式的骨质疏松症有关。ClC‐7变异的功能评估可能会提供有关其致病性的信息，但蛋白质的细胞定位阻碍了这种分析。在这里，我们研究了13个CLCN7突变的功能影响，这些突变在13个新发的严重或轻度骨质疏松症患者和一个已知的ADO2突变中发现。我们在ClC‐7蛋白同源模型中绘制了突变氨基酸残基，通过共聚焦显微镜评估了ClC‐7突变体和Ostm1的溶酶体共定位，并对质膜靶向突变体ClC‐7进行了膜片钳记录。最后，我们结合患者的临床特征分析了这些结果，并提出溶酶体中缺乏ClC‐7/Ostm1与严重的神经退行性变之间存在相关性。©2020美国骨与矿物研究协会（ASBMR）。
ClC‐7 is a chloride‐proton antiporter of the CLC protein family. In complex with its accessory protein Ostm‐1, ClC‐7 localizes to lysosomes and to the osteoclasts' ruffled border, where it plays a critical role in acidifying the resorption lacuna during bone resorption. Gene inactivation in mice causes severe osteopetrosis, neurodegeneration, and lysosomal storage disease. Mutations in the human CLCN7 gene are associated with diverse forms of osteopetrosis. The functional evaluation of ClC‐7 variants might be informative with respect to their pathogenicity, but the cellular localization of the protein hampers this analysis. Here we investigated the functional effects of 13 CLCN7 mutations identified in 13 new patients with severe or mild osteopetrosis and a known ADO2 mutation. We mapped the mutated amino acid residues in the homology model of ClC‐7 protein, assessed the lysosomal colocalization of ClC‐7 mutants and Ostm1 through confocal microscopy, and performed patch‐clamp recordings on plasma‐membrane‐targeted mutant ClC‐7. Finally, we analyzed these results together with the patients' clinical features and suggested a correlation between the lack of ClC‐7/Ostm1 in lysosomes and severe neurodegeneration. © 2020 American Society for Bone and Mineral Research (ASBMR).