title: Loss of vps54 function leads to vesicle traffic impairment, protein mis-sorting and embryonic lethality.
abstract: The identification of the mutation causing the phenotype of the amyotrophic lateral sclerosis (ALS) model mouse, wobbler, has linked motor neuron degeneration with retrograde vesicle traffic. The wobbler mutation affects protein stability of Vps54, a ubiquitously expressed vesicle-tethering factor and leads to partial loss of Vps54 function. Moreover, the Vps54 null mutation causes embryonic lethality, which is associated with extensive membrane blebbing in the neural tube and is most likely a consequence of impaired vesicle transport. Investigation of cells derived from wobbler and Vps54 null mutant embryos demonstrates impaired retrograde transport of the Cholera-toxin B subunit to the trans-Golgi network and mis-sorting of mannose-6-phosphate receptors and cargo proteins dependent on retrograde vesicle transport. Endocytosis assays demonstrate no difference between wobbler and wild type cells, indicating that the retrograde vesicle traffic to the trans-Golgi network, but not endocytosis, is affected in Vps54 mutant cells. The results obtained on wobbler cells were extended to test the use of cultured skin fibroblasts from human ALS patients to investigate the retrograde vesicle traffic. Analysis of skin fibroblasts of ALS patients will support the investigation of the critical role of the retrograde vesicle transport in ALS pathogenesis and might yield a diagnostic prospect.
authors.affiliation: Molecular Biology and Genetics Department, Aarhus University, Aarhus 8000, Denmark. tsj@mb.au.dk.
authors.forename: Páll
authors.initials: P
authors.lastname: Karlsson
authors.forename: Aida
authors.initials: A
authors.lastname: Droce
authors.forename: Jakob M
authors.initials: JM
authors.lastname: Moser
authors.forename: Simon
authors.initials: S
authors.lastname: Cuhlmann
authors.forename: Carolina Ortiz
authors.initials: CO
authors.lastname: Padilla
authors.forename: Peter
authors.initials: P
authors.lastname: Heimann
authors.forename: Jörg W
authors.initials: JW
authors.lastname: Bartsch
authors.forename: Annette
authors.initials: A
authors.lastname: Füchtbauer
authors.forename: Ernst-Martin
authors.initials: EM
authors.lastname: Füchtbauer
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitt-John
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002401:Cathepsin B / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D020964:Embryo Loss / Q000378:metabolism* / Q000473:pathology; D004622:Embryo, Mammalian / Q000378:metabolism / Q000473:pathology; D004705:Endocytosis; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D012867:Skin / Q000473:pathology; D022161:Transport Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D033921:Vesicular Transport Proteins / Q000172:deficiency* / Q000378:metabolism
chemical_list: D017527:Receptor, IGF Type 2; D033921:Vesicular Transport Proteins; C486750:Vps54 protein, mouse; D002772:Cholera Toxin; D002401:Cathepsin B