Original Paper

Acta Neuropathologica

, Volume 125, Issue 3, pp 413-423

hnRNP A3 binds to GGGGCC repeats and is a constituent of p62-positive/TDP43-negative inclusions in the hippocampus of patients with C9orf72 mutations

  • Kohji MoriAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-University
  • , Sven LammichAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-University
  • , Ian R. A. MackenzieAffiliated withDepartment of Pathology and Laboratory Medicine, University of British Columbia
  • , Ignasi FornéAffiliated withAdolf-Butenandt-Institute, Protein Analysis Unit, Ludwig-Maximilians-University
  • , Sonja ZilowAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-University
  • , Hans KretzschmarAffiliated withCenter for Neuropathology and Prion Research, Ludwig-Maximilians-University
  • , Dieter EdbauerAffiliated withDZNE, German Center for Neurodegenerative Diseases
  • , Jonathan JanssensAffiliated withNeurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIBLaboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp
  • , Gernot KleinbergerAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-UniversityDZNE, German Center for Neurodegenerative DiseasesNeurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIBLaboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp
    • , Marc CrutsAffiliated withNeurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIBLaboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp
    • , Jochen HermsAffiliated withDZNE, German Center for Neurodegenerative DiseasesMunich Cluster for Systems Neurology (SyNergy)
    • , Manuela NeumannAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-UniversityDZNE, German Center for Neurodegenerative DiseasesDepartment of Neuropathology, University of Tübingen
    • , Christine Van BroeckhovenAffiliated withNeurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIBLaboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp
    • , Thomas ArzbergerAffiliated withCenter for Neuropathology and Prion Research, Ludwig-Maximilians-University
    • , Christian HaassAffiliated withAdolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-UniversityDZNE, German Center for Neurodegenerative DiseasesMunich Cluster for Systems Neurology (SyNergy) Email author 

Abstract

Genetic analysis revealed the hexanucleotide repeat expansion GGGGCC within the regulatory region of the gene C9orf72 as the most common cause of familial amyotrophic lateral sclerosis and the second most common cause of frontotemporal lobar degeneration. Since repeat expansions might cause RNA toxicity via sequestration of RNA-binding proteins, we searched for proteins capable of binding to GGGGCC repeats. In vitro-transcribed biotinylated RNA containing hexanucleotide GGGGCC or, as control, AAAACC repeats were incubated with nuclear protein extracts. Using stringent filtering protocols 20 RNA-binding proteins with a variety of different functions in RNA metabolism, translation and transport were identified. A subset of these proteins was further investigated by immunohistochemistry in human autopsy brains. This revealed that hnRNP A3 formed neuronal cytoplasmic and intranuclear inclusions in the hippocampus of patients with C9orf72 repeat extensions. Confocal microcopy showed that these inclusions belong to the group of the so far enigmatic p62-positive/TDP-43 negative inclusions characteristically seen in autopsy cases of diseased C9orf72 repeat expansion carriers. Thus, we have identified one protein component of these pathognomonic inclusions.

Keywords

ALS C9orf72 FTLD hnRNP A3 Neurodegeneration TDP-43