Pascale Koebel, Bastien Morlet, Fabrice Riet, Wiley A. Clayton, Yasushi Iwasaki, Jianwen Deng, Véronique Pfister, Erwan Grandgirard, Jun Sone, Hiroaki Miyahara, Hugues Jacob, Luc Negroni, Kathryn McFadden, Mustapha Oulad-Abdelghani, Zhaoxia Wang, Manon Boivin, Daojun Hong, Anke A. Dijkstra, Nicolas Charlet-Berguerand, Frank Ruffenach, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Peking University First Hospital [Beijing, China], Amsterdam UMC, IWK Health Centre, Dalhousie University [Halifax], University of Pittsburgh Medical Center [Pittsburgh, PA, États-Unis] (UPMC), Nanchang University, Aichi Medical University, Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Peking University [Beijing], Amsterdam UMC - Amsterdam University Medical Center, ANR-18-CE16-0019,NewMutALS,Etude de nouvelles mutations dans le gene C9ORF72 responsables de Sclérose Latérale Amyotrophique(2018), ANR-10-LABX-0030,INRT,Integrative Biology : Nuclear dynamics- Regenerative medicine - Translational medicine(2010), ANR-10-IDEX-0002,UNISTRA,Par-delà les frontières, l'Université de Strasbourg(2010), European Project: 310659,EC:FP7:ERC,ERC-2012-StG_20111109,RNA DISEASES(2013), CHARLET BERGUERAND, NICOLAS, and Amsterdam Neuroscience - Neurodegeneration
Summary Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by the presence of intranuclear inclusions of unknown origin. NIID is caused by an expansion of GGC repeats in the 5′ UTR of the NOTCH2NLC (N2C) gene. We found that these repeats are embedded in a small upstream open reading frame (uORF) (uN2C), resulting in their translation into a polyglycine-containing protein, uN2CpolyG. This protein accumulates in intranuclear inclusions in cell and mouse models and in tissue samples of individuals with NIID. Furthermore, expression of uN2CpolyG in mice leads to locomotor alterations, neuronal cell loss, and premature death of the animals. These results suggest that translation of expanded GGC repeats into a novel and pathogenic polyglycine-containing protein underlies the presence of intranuclear inclusions and neurodegeneration in NIID., Graphical abstract, Highlights • NIID is a neurodegenerative disease caused by expansion of GGC repeats in NOTCH2NLC • These GGC repeats are translated into a polyglycine (polyG) protein • The polyG protein is toxic and forms intranuclear inclusions in cells and animals • Similarities between FXTAS and NIID define a new set of disorders: polyG diseases, The neurodegenerative disease NIID is caused by an expansion of GGC repeats in NOTCH2NLC. Boivin et al. found that these repeats are translated into a toxic polyglycine (polyG) protein that forms intranuclear inclusions. An identical mechanism exists in FXTAS, unveiling a novel group of genetic pathologies, the polyG diseases.