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Hardin JA. Directing autoimmunity to nucleoprotein particles: the impact of dendritic cells and interferon alpha in lupus. J Exp Med 2003; 197:681-5. [PMID: 12642600 PMCID: PMC2193850 DOI: 10.1084/jem.20030130] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- John A Hardin
- Laboratory for Cellular Physiology and Immunology, The Rockefeller University, Bronx, New York, NY 10021, USA.
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Takeda Y, Caudell P, Grady G, Wang G, Suwa A, Sharp GC, Dynan WS, Hardin JA. Human RNA Helicase A Is a Lupus Autoantigen That Is Cleaved During Apoptosis. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.11.6269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Proteolytic cleavage by caspases is the central event in cells undergoing apoptosis. Cleaved proteins are often targeted by autoantibodies, suggesting that the cleavage of self Ags enhances immunogenicity and is prone to induce an autoimmune response. We found autoantibodies that immunoprecipitated a 140-kDa RNA-associated protein, provisionally designated Pa, in 11 of 350 patient sera that were positive for antinuclear Abs in an immunofluorescence test. The Pa protein gave rise to three fragments with m.w. ranging from 120–130 kDa during anti-Fas-activated apoptosis. Pure caspase-3 cleaved the Pa protein into a 130-kDa fragment corresponding to the largest of these three products. Peptide sequence analysis of a tryptic digest from immunoaffinity-purified Pa showed 100% identity to human RNA helicase A (RHA). The identity of Pa with RHA was further confirmed by immunoblotting with rabbit anti-RHA Ab using anti-Pa immunoprecipitates as substrates. All 10 anti-RHA-positive patients who were clinically analyzed were diagnosed as having systemic lupus erythematosus, and 7 of them had lupus nephritis. RHA is a multifunctional protein with roles in cellular RNA synthesis and processing. Inactivation of RHA by cleavage may be an important part of the process leading to programmed cell death. The cleaved RHA fragments that are produced during apoptosis may trigger an autoimmune response in systemic lupus erythematosus.
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Affiliation(s)
- Yoshihiko Takeda
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
| | - Patricia Caudell
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
| | - Giuia Grady
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
| | - Grace Wang
- †Department of Medicine, University of Missouri, Columbia, MO 65212
| | - Akira Suwa
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
| | - Gordon C. Sharp
- †Department of Medicine, University of Missouri, Columbia, MO 65212
| | - William S. Dynan
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
| | - John A. Hardin
- *Program in Gene Regulation, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912; and
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