The IgE gene in primates exhibits extraordinary evolutionary diversity
- 252 Downloads
Membrane-bound IgE (mIgE) on B lymphocytes is essential for IgE production. Earlier studies showed that the ε chain of mIgE (mε) on human B cells has a “long” isoform, with an extra “CεmX” domain of 52 amino acid (aa) residues between the CH4 domain and the membrane-anchor segment, as compared to the conventional “short” isoform. Because CεmX provides an antigenic site for targeting IgE-expressing B cells to down-regulate IgE production in patients with allergy, analysis of CεmX in various animals is of great interest. Hence, we analyzed the ε Ig gene, in particular, its membrane exon regions encoding the membrane anchor peptide segment and CεmX domain, of 26 species of the order Primates and 12 species of seven non-Primate orders using data obtained experimentally or retrieved from GenBank. Our analyses reveal the unexpected finding that the genes of three extant tarsier species do not contain the membrane exons for mIgE. Another striking finding is that early evolved Strepsirhini primates such as lemurs and lorises do not have gene segments for the long isoform, whereas New World monkeys such as marmosets and squirrel monkeys allow the transcription of only the long isoform. In Old World monkeys and apes, including humans, the ε gene allows the transcription of both isoforms. This work thus reveals the dramatic differences in the gene segment encoding the mε C terminal region among the four major primate lineages: the Strepsirhini primates, the tarsiers, New World monkeys, and Old World monkeys and apes/humans.
KeywordsMembrane-bound IgE ε Immunoglobulin gene Membrane exons Primates Tarsiers Diversity
This work is supported by a grant, NSC99-2320-B-001-006-MY3, from the National Science Council, Taiwan. We thank Dr. George Perry of Arizona State University for the gift of DNA samples from two aye-ayes and Dr. Harry Wilson for editing the manuscript.
Conflict of interest
The authors have no financial conflicts of interest.
- Brightbill HD, Jeet S, Lin Z, Yan D, Zhou M, Tan M, Nguyen A, Yeh S, Delarosa D, Leong SR, Wong T, Chen Y, Ultsch M, Luis E, Ramani SR, Jackman J, Gonzalez L, Dennis MS, Chuntharapai A, DeForge L, Meng YG, Xu M, Eigenbrot C, Lee WP, Refino CJ, Balazs M, Wu LC (2010) Antibodies specific for a segment of human membrane IgE deplete IgE-producing B cells in humanized mice. J Clin Invest 120(6):2218–2229PubMedCrossRefGoogle Scholar
- Busse WW, Morgan WJ, Gergen PJ, Mitchell HE, Gern JE, Liu AH, Gruchalla RS, Kattan M, Teach SJ, Pongracic JA, Chmiel JF, Steinbach SF, Calatroni A, Togias A, Thompson KM, Szefler SJ, Sorkness CA (2011) Randomized trial of omalizumab (anti-IgE) for asthma in inner-city children. N Engl J Med 364(11):1005–1015PubMedCrossRefGoogle Scholar
- Casale TB, Busse WW, Kline JN, Ballas ZK, Moss MH, Townley RG, Mokhtarani M, Seyfert-Margolis V, Asare A, Bateman K, Deniz Y (2006) Omalizumab pretreatment decreases acute reactions after rush immunotherapy for ragweed-induced seasonal allergic rhinitis. J Allergy Clin Immunol 117(1):134–140PubMedCrossRefGoogle Scholar
- Reth M, Tasuku H, Frederick WA (1995) Antigen receptors on B lymphocytes. Immunoglobulin genes, 2nd edn. Academic, London, pp 129–142Google Scholar
- Vernersson M, Aveskogh M, Munday B, Hellman L (2002) Evidence for an early appearance of modern post-switch immunoglobulin isotypes in mammalian evolution (II); cloning of IgE, IgG1 and IgG2 from a monotreme, the duck-billed platypus, Ornithorhynchus anatinus. Eur J Immunol 32(8):2145–2155PubMedCrossRefGoogle Scholar