Pathobiologic Mechanisms of Neurodegeneration in Osteopetrosis Derived From Structural and Functional Analysis of 14 ClC-7 Mutants

Eleonora Di Zanni, Eleonora Palagano, Laura Lagostena, Dario Strina, Asma Rehman, Mario Abinun, Lien De Somer, Baldassarre Martire, Justin Brown, Ariana Kariminejad, Shanti Balasubramanian, Gareth Baynam, Fiorella Gurrieri, Maria A. Pisanti, Ilaria De Maggio, Miguel R. Abboud, Robert Chiesa, Christine P. Burren, Anna Villa, Cristina SobacchiAlessandra Picollo

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)531-545
Number of pages15
JournalJournal of Bone and Mineral Research
Volume36
Issue number3
DOIs
Publication statusPublished - Mar 2021

Keywords

  • CHLORIDE-PROTON EXCHANGER
  • LYSOSOMAL LOCALIZATION
  • MISSENSE MUTATIONS
  • OSTEOCLAST
  • OSTEOPETROSIS

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