1. A fully human IgG1 antibody targeting connexin 32 extracellular domain blocks CMTX1 hemichannel dysfunction in an in vitro model.
- Author
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Tettey-Matey A, Donati V, Cimmino C, Di Pietro C, Buratto D, Panarelli M, Reale A, Calistri A, Fornaini MV, Zhou R, Yang G, Zonta F, Marazziti D, and Mammano F
- Subjects
- Humans, Charcot-Marie-Tooth Disease genetics, Charcot-Marie-Tooth Disease pathology, Charcot-Marie-Tooth Disease metabolism, Protein Domains, Connexins metabolism, Connexins genetics, Gap Junction beta-1 Protein, Immunoglobulin G metabolism
- Abstract
Connexins (Cxs) are fundamental in cell-cell communication, functioning as gap junction channels (GJCs) that facilitate solute exchange between adjacent cells and as hemichannels (HCs) that mediate solute exchange between the cytoplasm and the extracellular environment. Mutations in the GJB1 gene, which encodes Cx32, lead to X-linked Charcot-Marie-Tooth type 1 (CMTX1), a rare hereditary demyelinating disorder of the peripheral nervous system (PNS) without an effective cure or treatment. In Schwann cells, Cx32 HCs are thought to play a role in myelination by enhancing intracellular and intercellular Ca
2+ signaling, which is crucial for proper PNS myelination. Single-point mutations (p.S85C, p.D178Y, p.F235C) generate pathological Cx32 HCs characterized by increased permeability ("leaky") or excessive activity ("hyperactive").We investigated the effects of abEC1.1-hIgG1, a fully human immunoglobulin G1 (hIgG1) monoclonal antibody, on wild-type (WT) and mutant Cx32D178Y HCs. Using HeLa DH cells conditionally co-expressing Cx and a genetically encoded Ca2+ biosensor (GCaMP6s), we demonstrated that mutant HCs facilitated 58% greater Ca2+ uptake in response to elevated extracellular Ca2+ concentrations ([Ca2+ ]ex ) compared to WT HCs. abEC1.1-hIgG1 dose-dependently inhibited Ca2+ uptake, achieving a 50% inhibitory concentration (EC50 ) of ~ 10 nM for WT HCs and ~ 80 nM for mutant HCs. Additionally, the antibody suppressed DAPI uptake and ATP release. An atomistic computational model revealed that serine 56 (S56) of the antibody interacts with aspartate 178 (D178) of WT Cx32 HCs, contributing to binding affinity. Despite the p.D178Y mutation weakening this interaction, the antibody maintained binding to the mutant HC epitope at sub-micromolar concentrations.In conclusion, our study shows that abEC1.1-hIgG1 effectively inhibits both WT and mutant Cx32 HCs, highlighting its potential as a therapeutic approach for CMTX1. These findings expand the antibody's applicability for treating diseases associated with Cx HCs and inform the rational design of next-generation antibodies with enhanced affinity and efficacy against mutant HCs., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: This study does not contain any individual participant data. No consent to publish is required. Competing interests: G. Yang, F. Zonta and F. Mammano report a patent family: “WO2017128880 – Fully human antibody specifically inhibiting connexin 26”, Inventors: Qu Z, Yang G, Mammano F, Zonta F, International application number: PCT/CN2016/109847, granted to ShanghaiTech University; and a patent family “WO2020237491 – Composition and Methods to treat Ectodermal Dysplasia 2, Clouston Type”, Inventors: Mammano F, Yang G, Zonta F, International Application No.: PCT/CN2019/088689, pending to ShanghaiTech University. The other authors declare no competing interests., (© 2024. The Author(s).)- Published
- 2024
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