title: Generation of novel covalent RNA-protein complexes in cells by ultraviolet B irradiation: implications for autoimmunity.
abstract: OBJECTIVE
  To determine whether ultraviolet B (UVB) irradiation induces novel modifications in autoantigens targeted during experimental photoinduced epidermal damage.
  
  
  METHODS
  To search for novel UVB-induced autoantigen modifications, lysates made from UVB-irradiated human keratinocytes or HeLa cells were immunoblotted using human autoantibodies that recognize ribonucleoprotein autoantigens. Novel autoantigen structures identified were further characterized using nucleases and RNA hybridization.
  
  
  RESULTS
  Human sera that recognize U1-70 kd (U1-70K) and La by immunoblotting also recognized multiple novel species when they were used to immunoblot lysates of UVB-irradiated keratinocytes or HeLa cells. These species were not present in control cells and were not observed when apoptosis was induced by Fas ligation or cytotoxic lymphocyte granule contents. Biochemical analysis using multiple assays revealed that these novel UVB-induced molecular species result from the covalent crosslinking between the U1 RNA and the hYRNA molecules with their associated proteins, including U1-70K, La, and likely components of the Sm particle.
  
  
  CONCLUSIONS
  These data demonstrate that UVB irradiation of live cells can directly induce covalent RNA-protein complexes, which are recognized by human autoantibodies. As previously described for other autoantigens, these covalent complexes of RNA and proteins may have important consequences in terms of antigen capture and processing.
authors.affiliation: Instituto Nacional de Cs. Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico. andrade@quetzal.innsz.mx
authors.forename: Felipe
authors.initials: F
authors.lastname: Andrade
authors.forename: Livia A
authors.initials: LA
authors.lastname: Casciola-Rosen
authors.forename: Antony
authors.initials: A
authors.lastname: Rosen
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D001323:Autoantibodies / Q000276:immunology; D001324:Autoantigens / Q000032:analysis*; D006367:HeLa Cells / Q000276:immunology / Q000473:pathology / Q000528:radiation effects; D006801:Humans; D015603:Keratinocytes / Q000276:immunology / Q000473:pathology / Q000528:radiation effects*; D012342:RNA, Small Nuclear / Q000276:immunology / Q000528:radiation effects*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology / Q000528:radiation effects*; D012261:Ribonucleoproteins / Q000276:immunology / Q000528:radiation effects*; D014466:Ultraviolet Rays; D000097585:SS-B Antigen
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D012342:RNA, Small Nuclear; D017412:Ribonucleoprotein, U1 Small Nuclear; D012261:Ribonucleoproteins; D000097585:SS-B Antigen; C405483:U1 small nuclear RNA