title: NEFA/nucleobindin-2 is a target autoantigen of the anti-Wa antibody and is associated with transfer RNA.
abstract: OBJECTIVE
  The anti-Wa antibody found in systemic sclerosis patients reacts with a transfer RNA (tRNA)-associated 48-kDa protein and immunoprecipitates several tRNAs. We investigated the Wa antigen and its binding to tRNA species.
  
  
  METHODS
  We performed molecular cloning of the Wa antigen and made its recombinant protein. To investigate Wa antigen distribution in the cell, we performed an indirect immunofluorescence study. To determine the Wa-bound tRNA species, we performed a reverse transcription (RT)-polymerase chain reaction (PCR) using the RNAs immunoprecipitated by anti-Wa antibody as templates, and synthetic primers of mammalian tRNA sequences. To clarify the tissue expression of Wa antigen, we performed quantitative and semi-quantitative PCR of the cDNA.
  
  
  RESULTS
  We demonstrated that the Wa antigen was identical to NEFA (DNA binding/EF-hand/acidic amino acid rich region), otherwise known as nucleobindin-2. A full-length and an alternative splice variant cDNA lacking exon 11 were isolated by cloning NEFA cDNA. Anti-Wa-positive sera stained both the nucleus and cytoplasm of HEp-2 cells. RT-PCR suggested that Wa binds at least six tRNA species. In human tissues, NEFA is expressed predominantly in exocrine glands.
  
  
  CONCLUSIONS
  We have demonstrated that the Wa antigen is NEFA or nucleobindin-2, which binds specific tRNA species, and is distributed in specific human tissues.
authors.affiliation: Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Imura
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Shirai
authors.forename: Takaki
authors.initials: T
authors.lastname: Nojima
authors.forename: Ran
authors.initials: R
authors.lastname: Nakashima
authors.forename: Hajime
authors.initials: H
authors.lastname: Yamagata
authors.forename: Kiyomitsu
authors.initials: K
authors.lastname: Miyachi
authors.forename: Hajime
authors.initials: H
authors.lastname: Yoshifuji
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawabata
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ohmura
authors.forename: Takashi
authors.initials: T
authors.lastname: Usui
authors.forename: Takao
authors.initials: T
authors.lastname: Fujii
authors.forename: Tsuneyo
authors.initials: T
authors.lastname: Mimori
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000235:genetics / Q000276:immunology*; D001324:Autoantigens / Q000235:genetics / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D008297:Male; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000276:immunology*; D000080866:Nucleobindins; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology; D012343:RNA, Transfer / Q000235:genetics / Q000276:immunology*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012595:Scleroderma, Systemic / Q000276:immunology; D013045:Species Specificity
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; C000630650:NUCB2 protein, human; D009419:Nerve Tissue Proteins; C000630651:Nucb1 protein, mouse; C000630652:Nucb1 protein, rat; D000080866:Nucleobindins; D020033:Protein Isoforms; C069985:Wa antigen; D012343:RNA, Transfer; D002118:Calcium