The IgE gene in primates exhibits extraordinary evolutionary diversity
The IgE gene in primates exhibits extraordinary evolutionary diversity
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DOI：
10.1007/s00251-011-0586-9
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发表时间：
2011-11
期刊：
影响因子：
3.2
通讯作者：
P. C. Wu;Jiun-Bo Chen;S. Kawamura;C. Roos;Stefan Merker;Chih-Chin Shih;B. Hsu;C. Lim;T. Chang
中科院分区：
文献类型：
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作者：
P. C. Wu;Jiun-Bo Chen;S. Kawamura;C. Roos;Stefan Merker;Chih-Chin Shih;B. Hsu;C. Lim;T. Chang
B淋巴细胞上的膜结合IgE（mIgE）对于IgE产生是必需的。早期研究表明，人B细胞上mIgE（mε）的ε链具有“长”同种型，与传统的“短”同种型相比，在CH 4结构域和膜锚定区段之间具有额外的52个氨基酸（aa）残基的“CεmX”结构域。由于CεmX提供了靶向IgE表达B细胞的抗原位点，以下调过敏患者的IgE产生，因此对各种动物中CεmX的分析具有极大的意义。因此，我们分析了26种灵长目动物和12种非灵长目动物的ε IG基因，特别是其膜外显子编码的膜锚肽段和CεmX结构域，使用实验获得的数据或从GenBank中检索的数据。我们的分析揭示了一个意想不到的发现，即三种现存的眼镜猴物种的基因不包含mIgE的膜外显子。另一个惊人的发现是，早期进化的链鼻目灵长类动物，如狐猴和懒猴，没有长同种型的基因片段，而新世界的猴子，如绒猴和松鼠猴，只允许长同种型的转录。在旧大陆的猴子和猿，包括人类，ε基因允许两种亚型的转录。因此，这项工作揭示了编码mε C末端区域的基因片段在四种主要灵长类谱系中的巨大差异：链鼻族灵长类、眼镜猴、新世界猴和旧世界猴和猿/人。
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.