title: Forced expression of desmin and desmin mutants in cultured cells: impact of myopathic missense mutations in the central coiled-coil domain on network formation.
abstract: We recently demonstrated that inherited disease-causing mutations clustered in the alpha-helical coiled-coil "rod" domain of the muscle-specific intermediate filament (IF) protein desmin display a wide range of inhibitory effects on regular in vitro assembly. In these studies, we showed that individual mutations exhibited phenotypes that were not, with respect to the severity of interference, predictable by our current knowledge of the structural design of IF proteins. Moreover, the behavior of some mutated proteins in a standard tissue culture cell expression system was found to be even more complex. Here, we systematically investigate the behavior of these disease mutants in four different cell types: three not containing desmin or the related IF protein vimentin and the standard fibroblast line 3T3, which has an extensive vimentin system. The ability of the mutants to form filaments in the vimentin-free cells varies considerably, and only the mutants forming IFs in vitro generate extended filamentous networks. Furthermore, these latter mutants integrate into the 3T3 vimentin network but all the others do not. Instead, they cause the endogenous network of 3T3 vimentin to reorganize into perinuclear bundles. In addition, most of these assembly-deficient mutant desmins completely segregate from the vimentin system. Instead, the small round to fibrillar particles formed distribute independently throughout the cytoplasm as well as between the collapsed vimentin filament arrays in the perinuclear area.
authors.affiliation: Department of Cardiology, University of Heidelberg, D-69120 Heidelberg, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Bär
authors.forename: Anna
authors.initials: A
authors.lastname: Kostareva
authors.forename: Gunnar
authors.initials: G
authors.lastname: Sjöberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Sejersen
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Katus
authors.forename: Harald
authors.initials: H
authors.lastname: Herrmann
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D002460:Cell Line; D045744:Cell Line, Tumor; D003893:Desmin / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D007382:Intermediate Filaments / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009135:Muscular Diseases / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense / Q000235:genetics*; D011485:Protein Binding; D014162:Transfection; D014746:Vimentin / Q000378:metabolism
chemical_list: D003893:Desmin; D014746:Vimentin