Autoantibodies to dsDNA cross-react with the arginine-glycine-rich domain of heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2) and promote methylation of hnRNP A2.
OBJECTIVE
This study was designed to clarify the internalization of anti-DNA antibodies (anti-DNA) into living cells in the pathogenesis of systemic lupus erythematosus (SLE) using anti-DNA monoclonal antibodies (mAbs).


METHODS
Anti-DNA mAbs 9D7, 9D7D2, 9A4, 5E3F5, 12B3H2 and 6E11E3 were prepared by a standard hybridoma procedure to determine the interaction of anti-DNA with proteins in different types of cells.


RESULTS
The anti-DNA mAbs reacted with two protein antigens (35 and 50 kDa) in the cells. The 35-kDa antigen was shown to have 100% homology with hnRNP A2. The arginine-glycine-rich domain in hnRNP A2 was found to be the reaction site, and the methylation of hnRNP A2 by PRMT1 (protein arginine methyltransferase 1) was increased by anti-DNA. Moreover, anti-DNA was demonstrated to bind and internalize into the cytoplasm and nucleus.


CONCLUSIONS
Nuclear localizing anti-DNA may cross-react with hnRNP A2 to modulate the inflammatory responses and polarize immune reactions associated with SLE.
Sun
K-H
KH
Faculty of Medical Technology and Institute of Biotechnology in Medicine, National Yang-Ming University, 155 Section 2, Lie-Nong Street, Shih-Pai, Taipei, Taiwan 112, ROC. ksun@ym.edu.tw
Tang
S-J
SJ
Wang
Y-S
YS
Lin
W-J
WJ
You
R-I
RI
D000595:Amino Acid Sequence; D000818:Animals; D000974:Antibodies, Antinuclear / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000276:immunology; D003593:Cytoplasm / Q000276:immunology; D000939:Epitopes; D005434:Flow Cytometry; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008745:Methylation; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D011484:Protein-Arginine N-Methyltransferases / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D000939:Epitopes; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; C439768:hnRNP A2; D011484:Protein-Arginine N-Methyltransferases