Molecular Analysis of a Major Antigenic Region of the 240-kD Protein of Mi-2 Autoantigen

J Clin Invest. 1995 Oct;96(4):1730-7. doi: 10.1172/JCI118218.

Abstract

Anti-Mi-2 autoantibody is strongly associated with dermatomyositis and found in sera of 20% of patients. Mi-2 antigen contains at least eight components and previous evidence suggested that the 240-kD protein was the antigenic component for at least some sera. In this study, anti-M-2 patient sera were used to screen human thymocyte and HeLa cell lambda gt11 expression libraries, and two clones from each had plaques specifically reactive with anti-Mi-2 sera. Studies with affinity-purified antibody supported the identification of the clones. All of 44 anti-Mi-2 sera reacted with the plaques, but none of 44 control sera reacted significantly. The cDNAs were identical, and full sequencing of one revealed an open reading frame spanning a 1,054-bp insert. Rescreening the library with the cDNA yielded a 1,589-bp cDNA that continued the open reading frame. The Mi-2 cDNA hybridized to a single 7.5-8.0 kb mRNA of HeLa cells, by Northern blot. Rabbit antiserum directed at a portion of the cDNA product reacted with HeLa 240-kD Mi-2 protein. The sequence was notable for four potential zinc-fingers and several charged regions. The protein encoded by the cDNA produced in vitro reacted with only one of five of the Mi-2 sera. These findings indicate that the Mi-2 240 kD is a novel protein that is antigenic for all Mi-2 sera, and strongly suggests that a major common epitope is conformational in nature.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases*
  • Amino Acid Sequence
  • Animals
  • Autoantibodies / immunology
  • Autoantigens / genetics*
  • Base Sequence
  • DNA Helicases*
  • DNA, Complementary / analysis
  • DNA, Complementary / chemistry
  • DNA, Complementary / isolation & purification
  • Dermatomyositis / immunology*
  • Epitopes
  • HeLa Cells
  • Humans
  • Male
  • Mi-2 Nucleosome Remodeling and Deacetylase Complex
  • Molecular Sequence Data
  • Molecular Weight
  • Rabbits
  • Zinc Fingers

Substances

  • Autoantibodies
  • Autoantigens
  • CHD4 protein, human
  • DNA, Complementary
  • Epitopes
  • Mi-2 Nucleosome Remodeling and Deacetylase Complex
  • Adenosine Triphosphatases
  • DNA Helicases

Associated data

  • GENBANK/U08379