title: Cytoplasmic poly-GA aggregates impair nuclear import of TDP-43 in C9orf72 ALS/FTLD.
abstract: A repeat expansion in the non-coding region of C9orf72 gene is the most common mutation causing frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Sense and antisense transcripts are translated into aggregating dipeptide repeat (DPR) proteins in all reading frames (poly-GA,-GP,-GR,-PA and -PR) through an unconventional mechanism. How these changes contribute to cytoplasmic mislocalization and aggregation of TDP-43 and thereby ultimately leading to neuron loss remains unclear. The repeat RNA itself and poly-GR/PR have been linked to impaired nucleocytoplasmic transport. Here, we show that compact cytoplasmic poly-GA aggregates impair nuclear import of a reporter containing the TDP-43 nuclear localization (NLS) signal. However, a reporter containing a non-classical PY-NLS was not affected. Moreover, poly-GA expression prevents TNFα induced nuclear translocation of p65 suggesting that poly-GA predominantly impairs the importin-α/β-dependent pathway. In neurons, prolonged poly-GA expression induces partial mislocalization of TDP-43 into cytoplasmic granules. Rerouting poly-GA to the nucleus prevented TDP-43 mislocalization, suggesting a cytoplasmic mechanism. In rescue experiments, expression of importin-α (KPNA3, KPNA4) or nucleoporins (NUP54, NUP62) restores the nuclear localization of the TDP reporter. Taken together, inhibition of nuclear import of TDP-43 by cytoplasmic poly-GA inclusions causally links the two main aggregating proteins in C9orf72 ALS/FTLD pathogenesis.
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.|Graduate School of Systemic Neuroscience (GSN), Ludwig-Maximilians-University Munich, Germany.
authors.forename: Bahram
authors.initials: B
authors.lastname: Khosravi
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.
authors.forename: Hannelore
authors.initials: H
authors.lastname: Hartmann
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: May
authors.affiliation: Image and Data Analysis Facility, German Center for Neurodegenerative Diseases (DZNE), Bonn, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Möhl
authors.affiliation: Graduate School of Systemic Neuroscience (GSN), Ludwig-Maximilians-University Munich, Germany.|Biomedical Center (BMC), Institute for Cell Biology (Anatomy III), Ludwig Maximilians University Munich, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Ederle
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.
authors.forename: Meike
authors.initials: M
authors.lastname: Michaelsen
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.|Munich Cluster of Systems Neurology (SyNergy), Feodor-Lynen-Str. 17, 81377 Munich, Germany.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Schludi
authors.affiliation: Graduate School of Systemic Neuroscience (GSN), Ludwig-Maximilians-University Munich, Germany.|Biomedical Center (BMC), Institute for Cell Biology (Anatomy III), Ludwig Maximilians University Munich, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Dormann
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Munich, Feodor-Lynen-Str. 17, 81377 Munich, Germany.|Graduate School of Systemic Neuroscience (GSN), Ludwig-Maximilians-University Munich, Germany.|Munich Cluster of Systems Neurology (SyNergy), Feodor-Lynen-Str. 17, 81377 Munich, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Edbauer
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D000073885:C9orf72 Protein; D042622:DNA Repeat Expansion; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D057174:Frontotemporal Lobar Degeneration / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D028901:alpha Karyopherins / Q000235:genetics / Q000378:metabolism
chemical_list: D000073885:C9orf72 Protein; C568651:C9orf72 protein, human; D004268:DNA-Binding Proteins; C106306:KPNA3 protein, human; C106259:KPNA4 protein, human; D008562:Membrane Glycoproteins; D019913:Nuclear Localization Signals; D028861:Nuclear Pore Complex Proteins; D011506:Proteins; C000598624:TARDBP protein, human; D014409:Tumor Necrosis Factor-alpha; D028901:alpha Karyopherins; C049312:nuclear pore protein p62