Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome
Background and objective: Recessive mutations in the SIL1 gene cause Marinesco-Sjögren syndrome (MSS), a rare neuropediatric disorder. MSS-patients typically present with congenital cataracts, intellectual disability, cerebellar ataxia and progressive vacuolar myopathy. However, atypical clinical pr...
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Frontiers Media S.A.
2019-06-01
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| Series: | Frontiers in Neurology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fneur.2019.00562/full |
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| author | Christian Gatz Denisa Hathazi Denisa Hathazi Ute Münchberg Stephan Buchkremer Thomas Labisch Ben Munro Rita Horvath Ana Töpf Joachim Weis Andreas Roos Andreas Roos Andreas Roos |
| author_facet | Christian Gatz Denisa Hathazi Denisa Hathazi Ute Münchberg Stephan Buchkremer Thomas Labisch Ben Munro Rita Horvath Ana Töpf Joachim Weis Andreas Roos Andreas Roos Andreas Roos |
| author_sort | Christian Gatz |
| collection | DOAJ |
| description | Background and objective: Recessive mutations in the SIL1 gene cause Marinesco-Sjögren syndrome (MSS), a rare neuropediatric disorder. MSS-patients typically present with congenital cataracts, intellectual disability, cerebellar ataxia and progressive vacuolar myopathy. However, atypical clinical presentations associated with SIL1 mutations have been described over the last years; compound heterozygosity of SIL1 missense mutations even resulted in a phenotype not fulfilling the clinical diagnostic criteria of MSS. Thus, a read-out system to evaluate reliably the pathogenicity of amino acid changes in SIL1 is needed. Here, we aim to provide suitable cellular biomarkers enabling the robust evaluation of pathogenicity of SIL1 mutations.Methods: Five SIL1 variants including one polymorphism (p.K132Q), three known pathogenic mutations (p.V231_I232del, p.G312R, and p.L457P) and one ambiguous missense variant (p.R92W) were studied along with the wild-type proteins in Hek293 in vitro models by cell biological assays, immunoprecipitation, immunoblotting, and immunofluorescence as well as electron microscopy. Moreover, the SIL1-interactomes were interrogated by tandem-affinity-purification and subsequent mass spectrometry.Results: Our combined studies confirmed the pathogenicity of p.V231_I232del, p.G312R, and p.L457P by showing instability of the proteins as well as tendency to form aggregates. This observation is in line with altered structure of the ER-Golgi system and vacuole formation upon expression of these pathogenic SIL1-mutants as well as the presence of oxidative or ER-stress. Reduced cellular fitness along with abnormal mitochondrial architecture could also be observed. Notably, both the polymorphic p.K132Q and the ambiguous p.R92W variants did not elicit such alterations. Study of the SIL1-interactome identified POC1A as a novel binding partner of wild-type SIL1; the interaction is disrupted upon the presence of pathogenic mutants but not influenced by the presence of benign variants. Disrupted SIL1-POC1A interaction is associated with centrosome disintegration.Conclusions: We developed a combination of cellular outcome measures to evaluate the pathogenicity of SIL1 variants in suitable in vitro models and demonstrated that the p. R92W missense variant is a polymorphism rather than a pathogenic mutation leading to MSS. |
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| language | English |
| last_indexed | 2024-12-12T18:52:19Z |
| publishDate | 2019-06-01 |
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| spelling | doaj.art-7f98a3f834db4bea907a64fca6f843902022-12-22T00:15:21ZengFrontiers Media S.A.Frontiers in Neurology1664-22952019-06-011010.3389/fneur.2019.00562440704Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren SyndromeChristian Gatz0Denisa Hathazi1Denisa Hathazi2Ute Münchberg3Stephan Buchkremer4Thomas Labisch5Ben Munro6Rita Horvath7Ana Töpf8Joachim Weis9Andreas Roos10Andreas Roos11Andreas Roos12Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, GermanyLeibniz-Institut für Analytische Wissenschaften—ISAS—e.V., Dortmund, GermanyDepartment of Clinical Neuroscience, University of Cambridge, Cambridge, United KingdomLeibniz-Institut für Analytische Wissenschaften—ISAS—e.V., Dortmund, GermanyInstitute of Neuropathology, RWTH Aachen University Hospital, Aachen, GermanyInstitute of Neuropathology, RWTH Aachen University Hospital, Aachen, GermanyDepartment of Clinical Neuroscience, University of Cambridge, Cambridge, United KingdomDepartment of Clinical Neuroscience, University of Cambridge, Cambridge, United KingdomInternational Centre for Life, Institute of Genetic Medicine, Newcastle upon Tyne, United KingdomInstitute of Neuropathology, RWTH Aachen University Hospital, Aachen, GermanyInstitute of Neuropathology, RWTH Aachen University Hospital, Aachen, GermanyLeibniz-Institut für Analytische Wissenschaften—ISAS—e.V., Dortmund, GermanyPediatric Neurology, Faculty of Medicine, University Childrens Hospital, University of Duisburg-Essen, Essen, GermanyBackground and objective: Recessive mutations in the SIL1 gene cause Marinesco-Sjögren syndrome (MSS), a rare neuropediatric disorder. MSS-patients typically present with congenital cataracts, intellectual disability, cerebellar ataxia and progressive vacuolar myopathy. However, atypical clinical presentations associated with SIL1 mutations have been described over the last years; compound heterozygosity of SIL1 missense mutations even resulted in a phenotype not fulfilling the clinical diagnostic criteria of MSS. Thus, a read-out system to evaluate reliably the pathogenicity of amino acid changes in SIL1 is needed. Here, we aim to provide suitable cellular biomarkers enabling the robust evaluation of pathogenicity of SIL1 mutations.Methods: Five SIL1 variants including one polymorphism (p.K132Q), three known pathogenic mutations (p.V231_I232del, p.G312R, and p.L457P) and one ambiguous missense variant (p.R92W) were studied along with the wild-type proteins in Hek293 in vitro models by cell biological assays, immunoprecipitation, immunoblotting, and immunofluorescence as well as electron microscopy. Moreover, the SIL1-interactomes were interrogated by tandem-affinity-purification and subsequent mass spectrometry.Results: Our combined studies confirmed the pathogenicity of p.V231_I232del, p.G312R, and p.L457P by showing instability of the proteins as well as tendency to form aggregates. This observation is in line with altered structure of the ER-Golgi system and vacuole formation upon expression of these pathogenic SIL1-mutants as well as the presence of oxidative or ER-stress. Reduced cellular fitness along with abnormal mitochondrial architecture could also be observed. Notably, both the polymorphic p.K132Q and the ambiguous p.R92W variants did not elicit such alterations. Study of the SIL1-interactome identified POC1A as a novel binding partner of wild-type SIL1; the interaction is disrupted upon the presence of pathogenic mutants but not influenced by the presence of benign variants. Disrupted SIL1-POC1A interaction is associated with centrosome disintegration.Conclusions: We developed a combination of cellular outcome measures to evaluate the pathogenicity of SIL1 variants in suitable in vitro models and demonstrated that the p. R92W missense variant is a polymorphism rather than a pathogenic mutation leading to MSS.https://www.frontiersin.org/article/10.3389/fneur.2019.00562/fullSIL1-interactomeMarinesco-Sjögren syndrome biomarkersSIL1 missense mutationPOC1AFAM134Bcentrosome |
| spellingShingle | Christian Gatz Denisa Hathazi Denisa Hathazi Ute Münchberg Stephan Buchkremer Thomas Labisch Ben Munro Rita Horvath Ana Töpf Joachim Weis Andreas Roos Andreas Roos Andreas Roos Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome Frontiers in Neurology SIL1-interactome Marinesco-Sjögren syndrome biomarkers SIL1 missense mutation POC1A FAM134B centrosome |
| title | Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome |
| title_full | Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome |
| title_fullStr | Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome |
| title_full_unstemmed | Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome |
| title_short | Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome |
| title_sort | identification of cellular pathogenicity markers for sil1 mutations linked to marinesco sjogren syndrome |
| topic | SIL1-interactome Marinesco-Sjögren syndrome biomarkers SIL1 missense mutation POC1A FAM134B centrosome |
| url | https://www.frontiersin.org/article/10.3389/fneur.2019.00562/full |
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