title: Autoantigenicity of DFS70 is restricted to the conformational epitope of C-terminal alpha-helical domain.
abstract: Autoantibodies against DFS70 (Dense Fine Speckles 70) are found in 30% of Japanese atopic dermatitis patients, and less frequently in patients with other diseases. We have recently reported that they are also seen in 11% of hospital workers, but in only approximately 2% of patients with systemic rheumatic disease. In this study, in order to investigate the possible pathological role of anti-DFS70 antibodies, fine epitope mapping was carried out using 93 anti-DFS70 autoantibody-positive sera. Immunoblotting using overlapping peptides failed to reveal major linear epitopes. Western blotting using various truncated proteins showed a strikingly uniform epitope distribution on a suspected tertiary structure expressed by DFS70(349-435). Some sera showed reactivity only in an immunoprecipitation assay using an in vitro translated DFS70. Circular dichroism analysis revealed that DFS(349-435) contains an approximately 40% alpha-helical conformation, while an overlapping, non-antigenic peptide is composed of random coiled structures. The skewed single major epitope enabled us to establish a highly quantitative ELISA for the epitope region. Antibody titers showed no significant differences between the diseased group and healthy individuals. We propose that anti-DFS70 antibody may be a natural autoantibody, which might modify or reflect the inflammatory process of various disorders.
authors.affiliation: Division of Connective Tissue Disease & Autoimmunity, Department of Dermatology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Sugiura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Watanabe
authors.forename: Mitoshi
authors.initials: M
authors.lastname: Kunimatsu
authors.forename: Masaki
authors.initials: M
authors.lastname: Mishima
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Tomita
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Muro
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D002648:Child; D002942:Circular Dichroism; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D047468:Immunoprecipitation; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014019:Tissue Donors; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D014157:Transcription Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001324:Autoantigens; D000939:Epitopes; D007106:Immune Sera; C504649:PSIP1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors