title: A conserved eEF2 coding variant in SCA26 leads to loss of translational fidelity and increased susceptibility to proteostatic insult.
abstract: The autosomal dominant spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of disorders exhibiting cerebellar atrophy and Purkinje cell degeneration whose subtypes arise from 31 distinct genetic loci. Our group previously published the locus for SCA26 on chromosome 19p13.3. In this study, we performed targeted deep sequencing of the critical interval in order to identify candidate causative variants in individuals from the SCA26 family. We identified a single variant that co-segregates with the disease phenotype that produces a single amino acid substitution in eukaryotic elongation factor 2. This substitution, P596H, sits in a domain critical for maintaining reading frame during translation. The yeast equivalent, P580H EF2, demonstrated impaired translocation, detected as an increased rate of -1 programmed ribosomal frameshift read-through in a dual-luciferase assay for observing translational recoding. This substitution also results in a greater susceptibility to proteostatic disruption, as evidenced by a more robust activation of a reporter gene driven by unfolded protein response activation upon challenge with dithiothreitol or heat shock in our yeast model system. Our results present a compelling candidate mutation and mechanism for the pathogenesis of SCA26 and further support the role of proteostatic disruption in neurodegenerative diseases.
authors.affiliation: Department of Neurology, Institute for Genomics and Systems Biology, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hekman
authors.forename: Guo-Yun
authors.initials: GY
authors.lastname: Yu
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Brown
authors.forename: Haipeng
authors.initials: H
authors.lastname: Zhu
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Du
authors.forename: Kristina
authors.initials: K
authors.lastname: Gervin
authors.forename: Dag Erik
authors.initials: DE
authors.lastname: Undlien
authors.forename: April
authors.initials: A
authors.lastname: Peterson
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stevanin
authors.forename: H Brent
authors.initials: HB
authors.lastname: Clark
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Pulst
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Bird
authors.forename: Kevin P
authors.initials: KP
authors.lastname: White
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Gomez
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D015153:Blotting, Western; D059019:Clinical Coding; D017124:Conserved Sequence / Q000235:genetics*; D054736:Elongation Factor 2 Kinase / Q000235:genetics* / Q000378:metabolism; D056426:Genetic Loci; D020022:Genetic Predisposition to Disease; D005838:Genotype; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D011487:Protein Conformation; D011689:Purkinje Cells / Q000378:metabolism / Q000473:pathology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017423:Sequence Analysis, RNA; D020754:Spinocerebellar Ataxias / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D015003:Yeasts / Q000235:genetics
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C517689:EEF2K protein, human; D054736:Elongation Factor 2 Kinase