title: Rab1-dependent ER-Golgi transport dysfunction is a common pathogenic mechanism in SOD1, TDP-43 and FUS-associated ALS.
abstract: Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophic lateral sclerosis (ALS) including SOD1, TDP-43 and FUS. Using a variety of cellular and biochemical techniques, we demonstrate that ALS-associated mutant TDP-43, FUS and SOD1 inhibit protein transport between the endoplasmic reticulum (ER) and Golgi apparatus in neuronal cells. ER-Golgi transport was also inhibited in embryonic cortical and motor neurons obtained from a widely used animal model (SOD1(G93A) mice), validating this mechanism as an early event in disease. Each protein inhibited transport by distinct mechanisms, but each process was dependent on Rab1. Mutant TDP-43 and mutant FUS both inhibited the incorporation of secretory protein cargo into COPII vesicles as they bud from the ER, and inhibited transport from ER to the ER-Golgi intermediate (ERGIC) compartment. TDP-43 was detected on the cytoplasmic face of the ER membrane, whereas FUS was present within the ER, suggesting that transport is inhibited from the cytoplasm by mutant TDP-43, and from the ER by mutant FUS. In contrast, mutant SOD1 destabilised microtubules and inhibited transport from the ERGIC compartment to Golgi, but not from ER to ERGIC. Rab1 performs multiple roles in ER-Golgi transport, and over-expression of Rab1 restored ER-Golgi transport, and prevented ER stress, mSOD1 inclusion formation and induction of apoptosis, in cells expressing mutant TDP-43, FUS or SOD1. Rab1 also co-localised extensively with mutant TDP-43, FUS and SOD1 in neuronal cells, and Rab1 formed inclusions in motor neurons of spinal cords from sporadic ALS patients, which were positive for ubiquitinated TDP-43, implying that Rab1 is misfolded and dysfunctional in sporadic disease. These results demonstrate that ALS-mutant forms of TDP-43, FUS, and SOD1 all perturb protein transport in the early secretory pathway, between ER and Golgi compartments. These data also imply that restoring Rab1-mediated ER-Golgi transport is a novel therapeutic target in ALS.
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.
authors: Kai Y
authors: KY
authors: Soo
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.|Department of Biomedical Sciences, Faculty of Medicine and Health Science, Macquarie University, North Ryde, NSW, Australia.
authors: Mark
authors: M
authors: Halloran
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.|Department of Biomedical Sciences, Faculty of Medicine and Health Science, Macquarie University, North Ryde, NSW, Australia.
authors: Vinod
authors: V
authors: Sundaramoorthy
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.|Department of Biomedical Sciences, Faculty of Medicine and Health Science, Macquarie University, North Ryde, NSW, Australia.
authors: Sonam
authors: S
authors: Parakh
authors: Department of Biomedical Sciences, Faculty of Medicine and Health Science, Macquarie University, North Ryde, NSW, Australia.
authors: Reka P
authors: RP
authors: Toth
authors: Menzies Research Institute Tasmania, University of Tasmania, Hobart, TAS, Australia.
authors: Katherine A
authors: KA
authors: Southam
authors: Department of Anatomical Pathology, Alfred Hospital, Prahran, VIC, Australia.|Department of Medicine, Central Clinical School, Monash University, Clayton, VIC, Australia.
authors: Catriona A
authors: CA
authors: McLean
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.
authors: Peter
authors: P
authors: Lock
authors: Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, TAS, Australia.
authors: Anna
authors: A
authors: King
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia.
authors: Manal A
authors: MA
authors: Farg
authors: Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, VIC, Australia. julie.atkin@mq.edu.au.|Department of Biomedical Sciences, Faculty of Medicine and Health Science, Macquarie University, North Ryde, NSW, Australia. julie.atkin@mq.edu.au.
authors: Julie D
authors: JD
authors: Atkin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D022181:COP-Coated Vesicles / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D034702:RNA-Binding Protein FUS / Q000235:genetics / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism / Q000473:pathology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D020761:rab1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C000599550:FUS protein, human; D034702:RNA-Binding Protein FUS; C000606290:SOD1 protein, human; C000598624:TARDBP protein, human; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D020761:rab1 GTP-Binding Proteins
keywords: Amyotrophic lateral sclerosis; ER–Golgi transport; FUS; SOD1; TDP-43