title: Expanded polyalanine tracts function as nuclear export signals and promote protein mislocalization via eEF1A1 factor.
abstract: Polyalanine (poly(A)) diseases are caused by the expansion of translated GCN triplet nucleotide sequences encoding poly(A) tracts in proteins. To date, nine human disorders have been found to be associated with poly(A) tract expansions, including congenital central hypoventilation syndrome and oculopharyngeal muscular dystrophy. Previous studies have demonstrated that unexpanded wild-type poly(A)-containing proteins localize to the cell nucleus, whereas expanded poly(A)-containing proteins primarily localize to the cytoplasm. Because most of these poly(A) disease proteins are transcription factors, this mislocalization causes cellular transcriptional dysregulation leading to cellular dysfunction. Correcting this faulty localization could potentially point to strategies to treat the aforementioned disorders, so there is a pressing need to identify the mechanisms underlying the mislocalization of expanded poly(A) protein. Here, we performed a glutathioneS-transferase pulldown assay followed by mass spectrometry and identified eukaryotic translation elongation factor 1 α1 (eEF1A1) as an interacting partner with expanded poly(A)-containing proteins. Strikingly, knockdown ofeEF1A1expression partially corrected the mislocalization of the expanded poly(A) proteins in the cytoplasm and restored their functions in the nucleus. We further demonstrated that the expanded poly(A) domain itself can serve as a nuclear export signal. Taken together, this study demonstrates that eEF1A1 regulates the subcellular location of expanded poly(A) proteins and is therefore a potential therapeutic target for combating the pathogenesis of poly(A) diseases.
authors.affiliation: From the Laboratory of Drosophila Research.|Biochemistry Program.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: From the Laboratory of Drosophila Research.|Biochemistry Program.
authors.forename: Nelson Ka Lam
authors.initials: NK
authors.lastname: Ng
authors.affiliation: From the Laboratory of Drosophila Research.|Biochemistry Program.
authors.forename: Alex Chun
authors.initials: AC
authors.lastname: Koon
authors.affiliation: From the Laboratory of Drosophila Research, hyechan@cuhk.edu.hk.|Biochemistry Program.|Cell and Molecular Biology Program, and.|Molecular Biotechnology Program, School of Life Sciences, Faculty of Science, and.|the Gerald Choa Neuroscience Centre, Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Ho Yin Edwin
authors.initials: HY
authors.lastname: Chan
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D007040:Hypoventilation / Q000151:congenital / Q000235:genetics / Q000378:metabolism; D039141:Muscular Dystrophy, Oculopharyngeal / Q000235:genetics / Q000378:metabolism; D049790:Nuclear Export Signals; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D020182:Sleep Apnea, Central / Q000235:genetics / Q000378:metabolism; D019680:Trinucleotide Repeat Expansion
chemical_list: C094814:EEF1A1 protein, human; D049790:Nuclear Export Signals; D020648:Peptide Elongation Factor 1; D010455:Peptides; C019529:polyalanine
keywords: Drosophila genetics; eEF1A; gene transcription; genetic disease; protein export; protein-protein interaction