Biochemical effects of mutations in the gene encoding the alpha subunit of eukaryotic initiation factor (eIF) 2B associated with Vanishing White Matter disease

BMC Medical Genetics

Christopher G. Proud¹  Noel C. Wortham² 

[1]South Australian Health and Medical Research Institute, Adelaide, SA5001, Australia

[2]Centre for Biological Sciences, University of Southampton, Life Sciences Building 85, Highfield Campus, Southampton SO17 1BJ, UK

关键词: VWM;    EIF2B1;    eIF2B;    Leukodystrophy;    CACH;   

Others  :  1223158
DOI  :  10.1186/s12881-015-0204-z

 received in 2015-03-18, accepted in 2015-07-14,  发布年份 2015

【 摘 要 】

Background

Leukoencephalopathy with Vanishing White Matter (VWM) is an autosomal recessive disorder caused by germline mutations in the genes EIF2B1-5, which encode the 5 subunits of the eukaryotic translation initiation factor eIF2B. To date, analysis of the biochemical effects of mutations in the EIF2B2-5 genes has been carried out, but no study has been performed on mutations in the EIF2B1 gene. This gene encodes eIF2Bα, the smallest subunit in eIF2B which has an important role in both the structure and regulation of the eIF2B complex.

Methods

eIF2B subunits were overexpressed in HEK293 cells and isolated from the resulting cell lysates by affinity chromatography. Formation of the eIF2B complex and binding of its substrate, eIF2, was assessed by western blot. Assays of the guanine nucleotide exchange (GEF) activity were also carried out.

Results

Of the 5 eIF2Bα mutations studied, we found 3 that showed loss or reduction of binding of eIF2Bα to the rest of the complex, one with increased GEF activity, and one where no effects on activity or complex formation were observed.

Conclusions

This is the first study on eIF2Bα VWM mutations. We show that some mutations cause expected decreases in GEF activity or complex formation, similar to a majority of observed VWM mutations. However, we also observe some unexpected changes which hint at other effects of these mutations on as yet undescribed functions of eIF2B.

【 授权许可】

   
2015 Wortham and Proud.

【 图 表 】

Fig. 1.

Figure 4.

Fig. 3.

【 参考文献 】

• [1]Bugiani M, Boor I, Powers JM, Scheper GC, van der Knaap MS. Leukoencephalopathy with vanishing white matter: a review. J Neuropathol Exp Neurol. 2010; 69:987-996.
• [2]Liu R, van der Lei HD, Wang X, Wortham NC, Tang H, van Berkel CG et al.. Severity of vanishing white matter disease does not correlate with deficits in eIF2B activity or the integrity of eIF2B complexes. Hum Mutat. 2011; 32:1036-1045.
• [3]Pavitt GD, Proud CG. Protein synthesis and its control in neuronal cells with a focus on vanishing white matter disease. Biochem Soc Trans. 2009; 37:1298-1310.
• [4]Bugiani M, Boor I, van Kollenburg B, Postma N, Polder E, van Berkel C et al.. Defective glial maturation in vanishing white matter disease. J Neuropathol Exp Neurol. 2011; 70:69-82.
• [5]Cabilly Y, Barbi M, Geva M, Marom L, Chetrit D, Ehrlich M et al.. Poor cerebral inflammatory response in eIF2B knock-in mice: implications for the aetiology of vanishing white matter disease. PLoS One. 2012; 7:e46715.
• [6]Geva M, Cabilly Y, Assaf Y, Mindroul N, Marom L, Raini G et al.. A mouse model for eukaryotic translation initiation factor 2B-leucodystrophy reveals abnormal development of brain white matter. Brain. 2010; 133:2448-2461.
• [7]van der Knaap MS, Leegwater PA, Konst AA, Visser A, Naidu S, Oudejans CB et al.. Mutations in each of the five subunits of translation initiation factor eIF2B can cause leukoencephalopathy with vanishing white matter. Ann Neurol. 2002; 51:264-270.
• [8]Wortham NC, Martinez M, Gordiyenko Y, Robinson CV, Proud CG. Analysis of the subunit organization of the eIF2B complex reveals new insights into its structure and regulation. FASEB J. 2014; 28:2225-2237.
• [9]Hinnebusch AG. Molecular mechanism of scanning and start codon selection in eukaryotes. Microbiol Mol Biol Rev. 2011; 75:434-67.
• [10]Gomez E, Mohammad SS, Pavitt GD. Characterization of the minimal catalytic domain within eIF2B: the guanine-nucleotide exchange factor for translation initiation. EMBO J. 2002; 21:5292-5301.
• [11]Koonin EV. Multidomain organization of eukaryotic guanine nucleotide exchange translation initiation factor eIF-2B subunits revealed by analysis of conserved sequence motifs. Protein Sci. 1995; 4:1608-1617.
• [12]Pavitt GD, Ramaiah KV, Kimball SR, Hinnebusch AG. eIF2 independently binds two distinct eIF2B subcomplexes that catalyze and regulate guanine-nucleotide exchange. Genes Dev. 1998; 12:514-526.
• [13]Wang X, Wortham NC, Liu R, Proud CG. Identification of residues that underpin interactions within the eukaryotic initiation factor (eIF2) 2B complex. J Biol Chem. 2012; 287:8263-8274.
• [14]Yang W, Hinnebusch AG. Identification of a regulatory subcomplex in the guanine nucleotide exchange factor eIF2B that mediates inhibition by phosphorylated eIF2. Mol Cell Biol. 1996; 16:6603-6616.
• [15]Elsby R, Heiber JF, Reid P, Kimball SR, Pavitt GD, Barber GN. The alpha subunit of eukaryotic initiation factor 2B (eIF2B) is required for eIF2-mediated translational suppression of vesicular stomatitis virus. J Virol. 2011; 85:9716-9725.
• [16]Fabian JR, Kimball SR, Heinzinger NK, Jefferson LS. Subunit assembly and guanine nucleotide exchange activity of eukaryotic initiation factor-2B expressed in Sf9 cells. J Biol Chem. 1997; 272:12359-12365.
• [17]Wek RC, Jiang HY, Anthony TG. Coping with stress: eIF2 kinases and translational control. Biochem Soc Trans. 2006; 34:7-11.
• [18]Kilberg MS, Shan J, Su N. ATF4-dependent transcription mediates signaling of amino acid limitation. Trends Endocrinol Metab. 2009; 20:436-443.
• [19]van der Voorn JP, van Kollenburg B, Bertrand G, Van Haren K, Scheper GC, Powers JM et al.. The unfolded protein response in vanishing white matter disease. J Neuropathol Exp Neurol. 2005; 64:770-775.
• [20]van Kollenburg B, van Dijk J, Garbern J, Thomas AA, Scheper GC, Powers JM et al.. Glia-specific activation of all pathways of the unfolded protein response in vanishing white matter disease. J Neuropathol Exp Neurol. 2006; 65:707-715.
• [21]Kantor L, Pinchasi D, Mintz M, Hathout Y, Vanderver A, Elroy-Stein O. A point mutation in translation initiation factor 2B leads to a continuous hyper stress state in oligodendroglial-derived cells. PLoS One. 2008; 3:e3783.
• [22]Li W, Wang X, van der Knaap MS, Proud CG. Mutations linked to leukoencephalopathy with vanishing white matter impair the function of the eukaryotic initiation factor 2B complex in diverse ways. Mol Cell Biol. 2004; 24:3295-3306.
• [23]Fogli A, Schiffmann R, Hugendubler L, Combes P, Bertini E, Rodriguez D et al.. Decreased guanine nucleotide exchange factor activity in eIF2B-mutated patients. Eur J Hum Genet. 2004; 12:561-566.
• [24]Horzinski L, Huyghe A, Cardoso MC, Gonthier C, Ouchchane L, Schiffmann R et al.. Eukaryotic initiation factor 2B (eIF2B) GEF activity as a diagnostic tool for EIF2B-related disorders. PLoS One. 2009; 4:e8318.
• [25]Jennings MD, Pavitt GD. eIF5 has GDI activity necessary for translational control by eIF2 phosphorylation. Nature. 2010; 465:378-381.
• [26]Jennings MD, Zhou Y, Mohammad-Qureshi SS, Bennett D, Pavitt GD. eIF2B promotes eIF5 dissociation from eIF2*GDP to facilitate guanine nucleotide exchange for translation initiation. Genes Dev. 2013; 27:2696-2707.
• [27]Ohlenbusch A, Henneke M, Brockmann K, Goerg M, Hanefeld F, Kohlschutter A et al.. Identification of ten novel mutations in patients with eIF2B-related disorders. Hum Mutat. 2005; 25:411.
• [28]Hannig EM, Williams NP, Wek RC, Hinnebusch AG. The translational activator GCN3 functions downstream from GCN1 and GCN2 in the regulatory pathway that couples GCN4 expression to amino acid availability in Saccharomyces cerevisiae. Genetics. 1990; 126:549-562.
• [29]Klein U, Ramirez MT, Kobilka BK, Von Zastrow M. A novel interaction between adrenergic receptors and the alpha-subunit of eukaryotic initiation factor 2B. J Biol Chem. 1997; 272:19099-19102.
• [30]Richardson JP, Mohammad SS, Pavitt GD. Mutations causing childhood ataxia with central nervous system hypomyelination reduce eukaryotic initiation factor 2B complex formation and activity. Mol Cell Biol. 2004; 24:2352-2363.
• [31]Hiyama TB, Ito T, Imataka H, Yokoyama S. Crystal structure of the alpha subunit of human translation initiation factor 2B. J Mol Biol. 2009; 392:937-951.
• [32]Pettersen EF, Goddard TD, Huang CC, Couch GS, Greenblatt DM, Meng EC et al.. UCSF Chimera–a visualization system for exploratory research and analysis. J Comput Chem. 2004; 25:1605-1612.
• [33]Maletkovic J, Schiffmann R, Gorospe JR, Gordon ES, Mintz M, Hoffman EP et al.. Genetic and clinical heterogeneity in eIF2B-related disorder. J Child Neurol. 2008; 23:205-215.
• [34]Pronk JC, van Kollenburg B, Scheper GC, van der Knaap MS. Vanishing white matter disease: a review with focus on its genetics. Ment Retard Dev Disabil Res Rev. 2006; 12:123-128.