title: Muscular Dystrophy Mutations Impair the Nuclear Envelope Emerin Self-assembly Properties.
abstract: More than 100 genetic mutations causing X-linked Emery-Dreifuss muscular dystrophy have been identified in the gene encoding the integral inner nuclear membrane protein emerin. Most mutations are nonsense or frameshift mutations that lead to the absence of emerin in cells. Only very few cases are due to missense or short in-frame deletions. Molecular mechanisms explaining the corresponding emerin variants' loss of function are particularly difficult to identify because of the mostly intrinsically disordered state of the emerin nucleoplasmic region. We now demonstrate that this EmN region can be produced as a disordered monomer, as revealed by nuclear magnetic resonance, but rapidly self-assembles in vitro. Increases in concentration and temperature favor the formation of long curvilinear filaments with diameters of approximately 10 nm, as observed by electron microscopy. Assembly of these filaments can be followed by fluorescence through Thioflavin-T binding and by Fourier-transform Infrared spectrometry through formation of β-structures. Analysis of the assembly properties of five EmN variants reveals that del95-99 and Q133H impact filament assembly capacities. In cells, these variants are located at the nuclear envelope, but the corresponding quantities of emerin-emerin and emerin-lamin proximities are decreased compared to wild-type protein. Furthermore, variant P183H favors EmN aggregation in vitro, and variant P183T provokes emerin accumulation in cytoplasmic foci in cells. Substitution of residue Pro183 might systematically favor oligomerization, leading to emerin aggregation and mislocalization in cells. Our results suggest that emerin self-assembly is necessary for its proper function and that a loss of either the protein itself or its ability to self-assemble causes muscular dystrophy.
authors.affiliation: Laboratoire de Biologie Structurale et Radiobiologie, Institute for Integrative Biology of the Cell (I2BC) , CEA Saclay Bât. 144, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Isaline
authors.initials: I
authors.lastname: Herrada
authors.affiliation: Laboratoire de Biologie Structurale et Radiobiologie, Institute for Integrative Biology of the Cell (I2BC) , CEA Saclay Bât. 144, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Samson
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, Institute for Integrative Biology of the Cell (I2BC) , CNRS Bât.34, 1 avenue de la terrasse, 91190 Gif-sur-Yvette, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Velours
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, Institute for Integrative Biology of the Cell (I2BC) , CNRS Bât.34, 1 avenue de la terrasse, 91190 Gif-sur-Yvette, France.
authors.forename: Louis
authors.initials: L
authors.lastname: Renault
authors.affiliation: Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University , 630 West 168th Street, New York, New York 10032, United States.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Östlund
authors.affiliation: Laboratoire de Biologie Structurale et Radiobiologie, Institute for Integrative Biology of the Cell (I2BC) , CEA Saclay Bât. 144, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Chervy
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molecular Pharmakologie (FMP) , 13125 Berlin, Germany.
authors.forename: Dmytro
authors.initials: D
authors.lastname: Puchkov
authors.affiliation: Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University , 630 West 168th Street, New York, New York 10032, United States.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Worman
authors.affiliation: Laboratoire de Physiologie du Muscle Strié, Université Paris Diderot-Paris 7 , CNRS, UMR 8251, Institut de Biologie Fonctionnelle et Adaptative, 4 rue M.A. Lagroua Weill Halle, 75205 Paris Cedex 13, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Buendia
authors.affiliation: Laboratoire de Biologie Structurale et Radiobiologie, Institute for Integrative Biology of the Cell (I2BC) , CEA Saclay Bât. 144, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Zinn-Justin
mesh_terms: D014644:Genetic Variation; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009136:Muscular Dystrophies / Q000235:genetics*; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D057165:Proteostasis Deficiencies / Q000235:genetics; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008565:Membrane Proteins; D009687:Nuclear Proteins; C092710:emerin