title: Identification of beta-actin as a candidate autoantigen in autoimmune inner ear disease.
abstract: It has been shown that sera from patients with autoimmune inner ear disease contain antibodies to several inner ear antigens. We report here the characterization of the 42-43 kDa protein against which a significant number of patients' sera react strongly. After separation of inner ear proteins from guinea-pig cochleas by SDS-PAGE, the band corresponding to the 42-43 kDa protein was digested with trypsin and the peptide fragments were separated by high-performance liquid chromatography. Two fractions were then subjected to amino acid sequencing by the classical automated Edman degradation. The sequence of a stretch of 15 amino acids of the first fragment was identical to that of amino acids 148-162 of beta-actin. The sequence of the 10 amino acids of the second fragment was also identical to beta-actin. On Western blots, monoclonal antibody directed against beta-actin reacted with the inner ear 42-43 kDa proteins. The serum samples from the patients and the monoclonal antibody reacted with the non-muscle actin used as antigen in Western blotting. Immunoblot analysis of inner ear proteins after two-dimensional gel electrophoresis showed a spot, corresponding to the region of the 43 kDa as compared to the protein standards. On the basis of these data it is concluded that the target 42-43 kDa protein for antibodies in sera of patients with autoimmune inner ear disease is beta-actin, a molecule, which has important and numerous functions inside cells. This is the first report to identify the cytoskeletal protein beta-actin as a candidate autoantigen in autoimmune inner ear disease.
authors: Laboratory of Autoimmunity and Department of Otorhinolaryngology, University of Louvain Medical School, 1200 Brussels, Belgium. Rachid.Boulassel@mblg.ucl.ac.be
authors: M R
authors: MR
authors: Boulassel
authors: J P
authors: JP
authors: Tomasi
authors: N
authors: N
authors: Deggouj
authors: M
authors: M
authors: Gersdorff
mesh_terms: D000199:Actins / Q000276:immunology*; D000818:Animals; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000276:immunology; D004427:Ear Diseases / Q000276:immunology*; D007758:Ear, Inner / Q000382:microbiology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006168:Guinea Pigs; D008297:Male
chemical_list: D000199:Actins; D001323:Autoantibodies; D001324:Autoantigens; D002352:Carrier Proteins