Autoreactive B cell responses to RNA-related antigens due to TLR7 gene duplication.
Science (New York, N.Y.) 2006 Jun 16; 312(5780):1669-72
Pisitkun P P, Deane J JA, Difilippantonio M MJ, Tarasenko T T, Satterthwaite A AB, Bolland S S
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Rockville, MD 20852, USA.
Antibodies against nuclear self-antigens are characteristic of systemic autoimmunity, although mechanisms promoting their generation and selection are unclear. Here, we report that B cells containing the Y-linked autoimmune accelerator (Yaa) locus are intrinsically biased toward nucleolar antigens because of increased expression of TLR7, a single-stranded RNA-binding innate immune receptor. The TLR7 gene is duplicated in Yaa mice because of a 4-Megabase expansion of the pseudoautosomal region. These results reveal high divergence in mouse Y chromosomes and represent a good example of gene copy number qualitatively altering a polygenic disease manifestation.