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Arcas-García A, Garcia-Prat M, Magallón-Lorenz M, Martín-Nalda A, Drechsel O, Ossowski S, Alonso L, Rivière JG, Soler-Palacín P, Colobran R, Sayós J, Martínez-Gallo M, Franco-Jarava C. The IL-2RG R328X nonsense mutation allows partial STAT-5 phosphorylation and defines a critical region involved in the leaky-SCID phenotype. Clin Exp Immunol 2020; 200:61-72. [PMID: 31799703 DOI: 10.1111/cei.13405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2019] [Indexed: 01/10/2023] Open
Abstract
In addition to their detection in typical X-linked severe combined immunodeficiency, hypomorphic mutations in the interleukin (IL)-2 receptor common gamma chain gene (IL2RG) have been described in patients with atypical clinical and immunological phenotypes. In this leaky clinical phenotype the diagnosis is often delayed, limiting prompt therapy in these patients. Here, we report the biochemical and functional characterization of a nonsense mutation in exon 8 (p.R328X) of IL2RG in two siblings: a 4-year-old boy with lethal Epstein-Barr virus-related lymphoma and his asymptomatic 8-month-old brother with a Tlow B+ natural killer (NK)+ immunophenotype, dysgammaglobulinemia, abnormal lymphocyte proliferation and reduced levels of T cell receptor excision circles. After confirming normal IL-2RG expression (CD132) on T lymphocytes, signal transducer and activator of transcription-1 (STAT-5) phosphorylation was examined to evaluate the functionality of the common gamma chain (γc ), which showed partially preserved function. Co-immunoprecipitation experiments were performed to assess the interaction capacity of the R328X mutant with Janus kinase (JAK)3, concluding that R328X impairs JAK3 binding to γc . Here, we describe how the R328X mutation in IL-2RG may allow partial phosphorylation of STAT-5 through a JAK3-independent pathway. We identified a region of three amino acids in the γc intracellular domain that may be critical for receptor stabilization and allow this alternative signaling. Identification of the functional consequences of pathogenic IL2RG variants at the cellular level is important to enable clearer understanding of partial defects leading to leaky phenotypes.
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Affiliation(s)
- A Arcas-García
- CIBBIM-Nanomedicine-Immune Regulation and Immunotherapy Group, Institut de Recerca Vall d'Hebron (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - M Garcia-Prat
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Pediatric Infectious Diseases and Immunodeficiencies Unit, Vall d'Hebron Campus Hospitalari, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - M Magallón-Lorenz
- CIBBIM-Nanomedicine-Immune Regulation and Immunotherapy Group, Institut de Recerca Vall d'Hebron (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - A Martín-Nalda
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Pediatric Infectious Diseases and Immunodeficiencies Unit, Vall d'Hebron Campus Hospitalari, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - O Drechsel
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - S Ossowski
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - L Alonso
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Hematopoietic Stem Cell Transplantation Unit, Pediatric Hematology and Oncology Department, Vall d'Hebron Campus Hospitalari, Barcelona, Spain
| | - J G Rivière
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Pediatric Infectious Diseases and Immunodeficiencies Unit, Vall d'Hebron Campus Hospitalari, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - P Soler-Palacín
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Pediatric Infectious Diseases and Immunodeficiencies Unit, Vall d'Hebron Campus Hospitalari, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - R Colobran
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Immunology Division, Department of Cell Biology, Physiology and Immunology, Hospital Universitari Vall d'Hebron (HUVH), Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain.,Genetics Department, Hospital Universitari Vall d'Hebron (HUVH), Barcelona, Spain
| | - J Sayós
- CIBBIM-Nanomedicine-Immune Regulation and Immunotherapy Group, Institut de Recerca Vall d'Hebron (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - M Martínez-Gallo
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Immunology Division, Department of Cell Biology, Physiology and Immunology, Hospital Universitari Vall d'Hebron (HUVH), Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - C Franco-Jarava
- Jeffrey Model Foundation Excellence Center, Barcelona, Spain.,Immunology Division, Department of Cell Biology, Physiology and Immunology, Hospital Universitari Vall d'Hebron (HUVH), Vall d'Hebron Research Institute (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
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Blanco-Grau A, Bonaventura-Ibars I, Coll-Cantí J, Melià MJ, Martinez R, Martínez-Gallo M, Andreu AL, Pinós T, García-Arumí E. Identification and biochemical characterization of the novel mutation m.8839G>C in the mitochondrial ATP6 gene associated with NARP syndrome. Genes Brain Behav 2013; 12:812-20. [PMID: 24118886 DOI: 10.1111/gbb.12089] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/25/2013] [Accepted: 09/30/2013] [Indexed: 12/21/2022]
Abstract
Mutations in the ATP6 gene are reported to be associated with Leber hereditary optic neuropathy, bilateral striatal necrosis, coronary atherosclerosis risk and neuropathy, ataxia and retinitis pigmentosa (NARP)/maternally inherited Leigh syndromes. Here, we present a patient with NARP syndrome, in whom a previously undescribed mutation was detected in the ATP6 gene: m.8839G>C. Several observations support the concept that m.8839G>C is pathogenically involved in the clinical phenotype of this patient: (1) the mutation was heteroplasmic in muscle; (2) mutation load was higher in the symptomatic patient than in the asymptomatic carriers; (3) cybrids carrying this mutation presented lower cell proliferation, increased mitochondrial DNA (mtDNA) copy number, increased steady-state OxPhos protein levels and decreased mitochondrial membrane potential with respect to isogenic wild-type cybrids; (4) this change was not observed in 2959 human mtDNAs from different mitochondrial haplogroups; (5) the affected amino acid was conserved in all the ATP6 sequences analyzed; and (6) using in silico prediction, the mutation was classified as 'probably damaging'. However, measurement of ATP synthesis showed no differences between wild-type and mutated cybrids. Thus, we suggest that m.8839G>C may lower the efficiency between proton translocation within F0 and F1 rotation, required for ATP synthesis. Further experiments are needed to fully characterize the molecular mechanisms involved in m.8839G>C pathogenicity.
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Affiliation(s)
- A Blanco-Grau
- Departament de Patología Mitocondrial i Neuromuscular, Universitari Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona
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