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He H, Li X, Guzman GA, Bungert-Plümke S, Franzen A, Lin X, Zhu H, Peng G, Zhang H, Yu Y, Sun S, Huang Z, Zhai Q, Chen Z, Peng J, Guzman RE. Expanding the genetic and phenotypic relevance of CLCN4 variants in neurodevelopmental condition: 13 new patients. J Neurol 2024; 271:4933-4948. [PMID: 38758281 DOI: 10.1007/s00415-024-12383-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 04/02/2024] [Accepted: 04/09/2024] [Indexed: 05/18/2024]
Abstract
OBJECTIVES CLCN4 variations have recently been identified as a genetic cause of X-linked neurodevelopmental disorders. This study aims to broaden the phenotypic spectrum of CLCN4-related condition and correlate it with functional consequences of CLCN4 variants. METHODS We described 13 individuals with CLCN4-related neurodevelopmental disorder. We analyzed the functional consequence of the unreported variants using heterologous expression, biochemistry, confocal fluorescent microscopy, patch-clamp electrophysiology, and minigene splicing assay. RESULTS We identified five novel (p.R41W, p.L348V, p.G480R, p.R603W, c.1576 + 5G > A) and three known (p.T203I, p.V275M, p.A555V) pathogenic CLCN4 variants in 13 Chinese patients. The p.V275M variant is found at high frequency and seen in four unrelated individuals. All had global developmental delay (GDD)/intellectual disability (ID). Seizures were present in eight individuals, and 62.5% of them developed refractory epilepsy. Five individuals without seizures showed moderate to severe GDD/ID. Developmental delay precedes seizure onset in most patients. The variants p.R41W, p.L348V, and p.R603W compromise the anion/exchange function of ClC-4. p.R41W partially impairs ClC-3/ClC-4 association. p.G480R reduces ClC-4 expression levels and impairs the heterodimerization with ClC-3. The c.1576 + 5G > A variant causes 22 bp deletion of exon 10. CONCLUSIONS We further define and broaden the clinical and mutational spectrum of CLCN4-related neurodevelopmental conditions. The p.V275M variant may be a potential hotspot CLCN4 variant in Chinese patients. The five novel variants cause loss of function of ClC-4. Transport dysfunction, protein instability, intracellular trafficking defect, or failure of ClC-4 to oligomerize may contribute to the pathophysiological events leading to CLCN4-related neurodevelopmental disorder.
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Affiliation(s)
- Hailan He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Xinyi Li
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - G A Guzman
- Institute of Biological Information Processing (IBI-7), Structural Biochemistry, Jülich Research Center, Jülich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Biological Information Processing (IBI-1), Molecular and Cell Physiology, Jülich Research Center, Jülich, Germany
| | - Arne Franzen
- Institute of Biological Information Processing (IBI-1), Molecular and Cell Physiology, Jülich Research Center, Jülich, Germany
| | - XueQin Lin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Hongmin Zhu
- Department of Rehabilitation, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Guilan Peng
- Department of Neurology, Xiamen Maternal and Child Health Care Hospital, Xiamen, China
| | - Hongwei Zhang
- Epilepsy Center, Children's Hospital Affiliated to Shandong University, Jinan, China
| | - Yonglin Yu
- Department of Rehabilitation, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Suzhen Sun
- Department of Pediatric Neurology, Hebei Children's Hospital, Hebei Medical University, Shijiazhuang, China
| | - Zhongqin Huang
- Department of Neurology, Xiamen Maternal and Child Health Care Hospital, Xiamen, China
| | - Qiongxiang Zhai
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangzhou, China
| | - Zheng Chen
- Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.
| | - Raul E Guzman
- Institute of Biological Information Processing (IBI-1), Molecular and Cell Physiology, Jülich Research Center, Jülich, Germany.
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Sahly AN, Sierra-Marquez J, Bungert-Plümke S, Franzen A, Mougharbel L, Berrahmoune S, Dassi C, Poulin C, Srour M, Guzman RE, Myers KA. Genotype-phenotype correlation in CLCN4-related developmental and epileptic encephalopathy. Hum Genet 2024; 143:667-681. [PMID: 38578438 DOI: 10.1007/s00439-024-02668-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 03/07/2024] [Indexed: 04/06/2024]
Abstract
CLCN4-related disorder is a rare X-linked neurodevelopmental condition with a pathogenic mechanism yet to be elucidated. CLCN4 encodes the vesicular 2Cl-/H+ exchanger ClC-4, and CLCN4 pathogenic variants frequently result in altered ClC-4 transport activity. The precise cellular and molecular function of ClC-4 remains unknown; however, together with ClC-3, ClC-4 is thought to have a role in the ion homeostasis of endosomes and intracellular trafficking. We reviewed our research database for patients with CLCN4 variants and epilepsy, and performed thorough phenotyping. We examined the functional properties of the variants in mammalian cells using patch-clamp electrophysiology, protein biochemistry, and confocal fluorescence microscopy. Three male patients with developmental and epileptic encephalopathy were identified, with differing phenotypes. Patients #1 and #2 had normal growth parameters and normal-appearing brains on MRI, while patient #3 had microcephaly, microsomia, complete agenesis of the corpus callosum and cerebellar and brainstem hypoplasia. The p.(Gly342Arg) variant of patient #1 significantly impaired ClC-4's heterodimerization capability with ClC-3 and suppressed anion currents. The p.(Ile549Leu) variant of patient #2 and p.(Asp89Asn) variant of patient #3 both shift the voltage dependency of transport activation by 20 mV to more hyperpolarizing potentials, relative to the wild-type, with p.(Asp89Asn) favouring higher transport activity. We concluded that p.(Gly342Arg) carried by patient #1 and the p.(Ile549Leu) expressed by patient #2 impair ClC-4 transport function, while the p.(Asp89Asn) variant results in a gain-of-transport function; all three variants result in epilepsy and global developmental impairment, but with differences in epilepsy presentation, growth parameters, and presence or absence of brain malformations.
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Affiliation(s)
- Ahmed N Sahly
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
- Department of Neurosciences, King Faisal Specialist Hospital & Research Centre, Jeddah, Saudi Arabia
| | - Juan Sierra-Marquez
- Institute of Biological Information Processing; Biological Molecular and Cell Physiology (IBI-1), Molecular and Cell Physiology, Research Center Jülich , GmbH Leo-Brandt-Strasse 1, 52428, Jülich, Germany
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Biological Information Processing; Biological Molecular and Cell Physiology (IBI-1), Molecular and Cell Physiology, Research Center Jülich , GmbH Leo-Brandt-Strasse 1, 52428, Jülich, Germany
| | - Arne Franzen
- Institute of Biological Information Processing; Biological Molecular and Cell Physiology (IBI-1), Molecular and Cell Physiology, Research Center Jülich , GmbH Leo-Brandt-Strasse 1, 52428, Jülich, Germany
| | - Lina Mougharbel
- Research Institute of the McGill University Medical Centre, Montreal, QC, Canada
| | - Saoussen Berrahmoune
- Research Institute of the McGill University Medical Centre, Montreal, QC, Canada
| | - Christelle Dassi
- Research Institute of the McGill University Medical Centre, Montreal, QC, Canada
| | - Chantal Poulin
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, PQ, H4A 3J1, Canada
| | - Myriam Srour
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada
- Research Institute of the McGill University Medical Centre, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, PQ, H4A 3J1, Canada
| | - Raul E Guzman
- Institute of Biological Information Processing; Biological Molecular and Cell Physiology (IBI-1), Molecular and Cell Physiology, Research Center Jülich , GmbH Leo-Brandt-Strasse 1, 52428, Jülich, Germany.
| | - Kenneth A Myers
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, QC, Canada.
- Research Institute of the McGill University Medical Centre, Montreal, QC, Canada.
- Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, 1001 Boulevard Décarie, Montreal, PQ, H4A 3J1, Canada.
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Li S, Zhang W, Liang P, Zhu M, Zheng B, Zhou W, Wang C, Zhao X. Novel variants in the CLCN4 gene associated with syndromic X-linked intellectual disability. Front Neurol 2023; 14:1096969. [PMID: 37789889 PMCID: PMC10542403 DOI: 10.3389/fneur.2023.1096969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 08/15/2023] [Indexed: 10/05/2023] Open
Abstract
Objective The dysfunction of the CLCN4 gene can lead to X-linked intellectual disability and Raynaud-Claes syndrome (MRXSRC), characterized by severe cognitive impairment and mental disorders. This study aimed to investigate the genetic defects and clinical features of Chinese children with CLCN4 variants and explore the effect of mutant ClC-4 on the protein expression level and subcellular localization through in vitro experiments. Methods A total of 401 children with intellectual disabilities were screened for genetic variability using whole-exome sequencing (WES). Clinical data, including age, sex, perinatal conditions, and environmental exposure, were collected. Cognitive, verbal, motor, and social behavioral abilities were evaluated. Candidate variants were verified using Sanger sequencing, and their pathogenicity and conservation were analyzed using in silico prediction tools. Protein expression and localization of mutant ClC-4 were measured using Western blotting (WB) and immunofluorescence microscopy. The impact of a splice site variant was assessed with a minigene assay. Results Exome analysis identified five rare CLCN4 variants in six unrelated patients with intellectual disabilities, including two recurrent heterozygous de novo missense variants (p.D89N and p.A555V) in three female patients, and two hemizygous missense variants (p.N141S and p.R694Q) and a splicing variant (c.1390-12T > G) that are maternally inherited in three male patients. The p.N141S variant and the splicing variant c.1390-12(T > G were novel, while p.R694Q was identified in two asymptomatic heterozygous female patients. The six children with CLCN4 variants exhibited a neurodevelopmental spectrum disease characterized by intellectual disability (ID), delayed speech, autism spectrum disorders (ASD), microcephaly, hypertonia, and abnormal imaging findings. The minigene splicing result indicated that the c.1390-12T > G did not affect the splicing of CLCN4 mRNA. In vitro experiments showed that the mutant protein level and localization of mutant protein are similar to the wild type. Conclusion The study identified six probands with CLCN4 gene variants associated with X-linked ID. It expanded the gene and phenotype spectrum of CLCN4 variants. The bioinformatic analysis supported the pathogenicity of CLCN4 variants. However, these CLCN4 gene variants did not affect the ClC-4 expression levels and protein location, consistent with previous studies. Further investigations are necessary to investigate the pathogenetic mechanism.
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Affiliation(s)
- Sinan Li
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Wenxin Zhang
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Piao Liang
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Min Zhu
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Wei Zhou
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaoke Zhao
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Nanjing, China
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Kolen B, Borghans B, Kortzak D, Lugo V, Hannack C, Guzman RE, Ullah G, Fahlke C. Vesicular glutamate transporters are H +-anion exchangers that operate at variable stoichiometry. Nat Commun 2023; 14:2723. [PMID: 37169755 PMCID: PMC10175566 DOI: 10.1038/s41467-023-38340-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 04/26/2023] [Indexed: 05/13/2023] Open
Abstract
Vesicular glutamate transporters accumulate glutamate in synaptic vesicles, where they also function as a major Cl- efflux pathway. Here we combine heterologous expression and cellular electrophysiology with mathematical modeling to understand the mechanisms underlying this dual function of rat VGLUT1. When glutamate is the main cytoplasmic anion, VGLUT1 functions as H+-glutamate exchanger, with a transport rate of around 600 s-1 at -160 mV. Transport of other large anions, including aspartate, is not stoichiometrically coupled to H+ transport, and Cl- permeates VGLUT1 through an aqueous anion channel with unitary transport rates of 1.5 × 105 s-1 at -160 mV. Mathematical modeling reveals that H+ coupling is sufficient for selective glutamate accumulation in model vesicles and that VGLUT Cl- channel function increases the transport efficiency by accelerating glutamate accumulation and reducing ATP-driven H+ transport. In summary, we provide evidence that VGLUT1 functions as H+-glutamate exchanger that is partially or fully uncoupled by other anions.
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Affiliation(s)
- Bettina Kolen
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Bart Borghans
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Daniel Kortzak
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Victor Lugo
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Cora Hannack
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Raul E Guzman
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL, 33620, USA
| | - Christoph Fahlke
- Institute of Biological Information Processing, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52428, Jülich, Germany.
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Sierra-Marquez J, Willuweit A, Schöneck M, Bungert-Plümke S, Gehlen J, Balduin C, Müller F, Lampert A, Fahlke C, Guzman RE. ClC-3 regulates the excitability of nociceptive neurons and is involved in inflammatory processes within the spinal sensory pathway. Front Cell Neurosci 2022; 16:920075. [PMID: 37124866 PMCID: PMC10134905 DOI: 10.3389/fncel.2022.920075] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
ClC-3 Cl–/H+ exchangers are expressed in multiple endosomal compartments and likely modify intra-endosomal pH and [Cl–] via the stoichiometrically coupled exchange of two Cl– ions and one H+. We studied pain perception in Clcn3–/– mice and found that ClC-3 not only modifies the electrical activity of peripheral nociceptors but is also involved in inflammatory processes in the spinal cord. We demonstrate that ClC-3 regulates the number of Nav and Kv ion channels in the plasma membrane of dorsal root ganglion (DRG) neurons and that these changes impair the age-dependent decline in excitability of sensory neurons. To distinguish the role of ClC-3 in Cl–/H+ exchange from its other functions in pain perception, we used mice homozygous for the E281Q ClC-3 point mutation (Clcn3E281Q/E281Q), which completely eliminates transport activity. Since ClC-3 forms heterodimers with ClC-4, we crossed these animals with Clcn4–/– to obtain mice completely lacking in ClC-3-associated endosomal chloride–proton transport. The electrical properties of Clcn3E281Q/E281Q/Clcn4–/– DRG neurons were similar to those of wild-type cells, indicating that the age-dependent adjustment of neuronal excitability is independent of ClC-3 transport activity. Both Clcn3–/– and Clcn3E281Q/E281Q/Clcn4–/– animals exhibited microglial activation in the spinal cord, demonstrating that competent ClC-3 transport is needed to maintain glial cell homeostasis. Our findings illustrate how reduced Cl–/H+ exchange contributes to inflammatory responses and demonstrate a role for ClC-3 in the homeostatic regulation of neuronal excitability beyond its function in endosomal ion balance.
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Affiliation(s)
- Juan Sierra-Marquez
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Antje Willuweit
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Michael Schöneck
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Jana Gehlen
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Carina Balduin
- Medical Imaging Physics, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Frank Müller
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | | | - Christoph Fahlke
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Raul E. Guzman
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
- *Correspondence: Raul E. Guzman,
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