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Slynko I, Nguyen S, Hamilton EMC, Wisse LE, de Esch IJP, de Graaf C, Bruning JB, Proud CG, Abbink TEM, van der Knaap MS. Vanishing white matter: Eukaryotic initiation factor 2B model and the impact of missense mutations. Mol Genet Genomic Med 2021; 9:e1593. [PMID: 33432707 PMCID: PMC8104162 DOI: 10.1002/mgg3.1593] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 12/12/2020] [Accepted: 12/21/2020] [Indexed: 12/21/2022] Open
Abstract
Background Vanishing white matter (VWM) is a leukodystrophy, caused by recessive mutations in eukaryotic initiation factor 2B (eIF2B)‐subunit genes (EIF2B1–EIF2B5); 80% are missense mutations. Clinical severity is highly variable, with a strong, unexplained genotype–phenotype correlation. Materials and Methods With information from a recent natural history study, we severity‐graded 97 missense mutations. Using in silico modeling, we created a new human eIF2B model structure, onto which we mapped the missense mutations. Mutated residues were assessed for location in subunits, eIF2B complex, and functional domains, and for information on biochemical activity. Results Over 50% of mutations have (ultra‐)severe phenotypic effects. About 60% affect the ε‐subunit, containing the catalytic domain, mostly with (ultra‐)severe effects. About 55% affect subunit cores, with variable clinical severity. About 36% affect subunit interfaces, mostly with severe effects. Very few mutations occur on the external eIf2B surface, perhaps because they have minor functional effects and are tolerated. One external surface mutation affects eIF2B‐substrate interaction and is associated with ultra‐severe phenotype. Conclusion Mutations that lead to (ultra‐)severe disease mostly affect amino acids with pivotal roles in complex formation and function of eIF2B. Therapies for VWM are emerging and reliable mutation‐based phenotype prediction is required for propensity score matching for trials and in the future for individualized therapy decisions.
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Affiliation(s)
- Inna Slynko
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Stephanie Nguyen
- Institute for Photonics and Advanced Sensing (IPAS), School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Eline M C Hamilton
- Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit and Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Lisanne E Wisse
- Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit and Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Iwan J P de Esch
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Chris de Graaf
- Division of Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - John B Bruning
- Institute for Photonics and Advanced Sensing (IPAS), School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Christopher G Proud
- Hopwood Centre for Neurobiology and Lifelong Health Theme, South Australian Health & Medical Research Institute, Adelaide, SA, Australia.,School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Truus E M Abbink
- Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit and Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit and Amsterdam Neuroscience, Amsterdam, the Netherlands.,Department of Functional Genomics, Amsterdam Neuroscience, VU University, Amsterdam, the Netherlands
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Ferreira MC, Dorboz I, Boespflug-Tanguy O. Efficient detection of frequent eIF2B mutations for the rapid molecular diagnosis of CACH/VWM syndrome. Clin Biochem 2015; 48:1317-23. [PMID: 26162493 DOI: 10.1016/j.clinbiochem.2015.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/05/2015] [Accepted: 07/02/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES The aim of this study was to develop a reliable, rapid and cost-effective molecular diagnostic assay allowing widespread routine investigation of eIF2B-related disorders (CACH/VWM syndrome). This heterogeneous disease is caused by autosomal recessive mutations in the genes encoding the five subunits of the translation-initiation factor eIF2B. Such a diagnostic method would be particularly adapted to the apparently acute presentation of the disease. DESIGN AND METHODS We developed a multiplex PCR amplification method for 7 genomic regions of the eIF2B genes in a single run. This method targeted the 8 most frequent mutations representing 61.4% of all mutations identified to date in our laboratory. These mutations affected eIF2B2 exon 5, eIF2B3 exon 2, eIF2B4 exons 8 and 11 and eIF2B5 exons 5, 7 and 8. PCR products were then pooled and subjected to a primer-extension assay validated using previously genotyped samples. RESULTS The results were compared to screening and/or direct sequencing methods: 100% agreement between methods confirmed equivalent sensitivity and specificity. The new assay was highly superior in terms of cost, time to results and robustness despite sample heterogeneity. CONCLUSIONS This genotyping strategy allows the detection of all eIF2B mutations targeted. A second multiplex primer-extension assay is in development to detect the 11 next-most frequent mutations, thus raising the global detection rate to 76.8%. Our approach is widely applicable as it involves standard techniques and equipment. Moreover, it can easily be further adapted to the clinical and genetic heterogeneity of eIF2B-related disorders by including or excluding mutations.
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Affiliation(s)
- Marie-Céleste Ferreira
- CHU Clermont-Ferrand, Molecular Biology Laboratory, Biochemistry Department, Clermont-Ferrand, France; GReD, UMR INSERM 931, CNRS 6247, Faculty of Medicine, Clermont-Ferrand, France.
| | - Imen Dorboz
- Inserm U1141, Paris Diderot University, Sorbonne Paris Cité, DHU PROTECT, Robert Debré Hospital, Paris, France.
| | - Odile Boespflug-Tanguy
- Inserm U1141, Paris Diderot University, Sorbonne Paris Cité, DHU PROTECT, Robert Debré Hospital, Paris, France; Reference Center For Leukodystrophies, Department of Neuropediatrics and Metabolic Diseases, Robert Debré Hospital, AP-HP, Paris, France.
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Lin Y, Pang X, Huang G, Jamison S, Fang J, Harding HP, Ron D, Lin W. Impaired eukaryotic translation initiation factor 2B activity specifically in oligodendrocytes reproduces the pathology of vanishing white matter disease in mice. J Neurosci 2014; 34:12182-91. [PMID: 25186761 DOI: 10.1523/JNEUROSCI.1373-14.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vanishing white matter disease (VWMD) is an inherited autosomal-recessive hypomyelinating disease caused by mutations in eukaryotic translation initiation factor 2B (eIF2B). eIF2B mutations predominantly affect the brain white matter, and the characteristic features of VWMD pathology include myelin loss and foamy oligodendrocytes. Activation of pancreatic endoplasmic reticulum kinase (PERK) has been observed in oligodendrocytes in VWMD. PERK activation in response to endoplasmic reticulum stress attenuates eIF2B activity by phosphorylating eIF2α, suggesting that impaired eIF2B activity in oligodendrocytes induced by VWMD mutations or PERK activation exploit similar mechanisms to promote selective white matter pathology in VWMD. Using transgenic mice that allow for temporally controlled activation of PERK specifically in oligodendrocytes, we discovered that strong PERK activation in oligodendrocytes during development suppressed eIF2B activity and reproduced the characteristic features of VWMD in mice, including hypomyelinating phenotype, foamy oligodendrocytes, and myelin loss. Notably, impaired eIF2B activity induced by PERK activation in oligodendrocytes of fully myelinated adult mice had minimal effects on morphology or function. Our observations point to a cell-autonomous role of impaired eIF2B activity in myelinating oligodendrocytes in the pathogenesis of VWMD.
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