Expansion of the silkworm GMC oxidoreductase genes is associated with immunity.
Expansion of the silkworm GMC oxidoreductase genes is associated with immunity.
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DOI：
10.1016/j.ibmb.2012.09.006
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发表时间：
2012-12
影响因子：
3.8
通讯作者：
Wei Sun;Yi-Hong Shen;Wen-juan Yang;Yun Cao;Z. Xiang;Ze Zhang
中科院分区：
文献类型：
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作者：
Wei Sun;Yi-Hong Shen;Wen-juan Yang;Yun Cao;Z. Xiang;Ze Zhang
葡萄糖-甲醇-胆碱(GMC)氧化还原酶是昆虫中的一个大基因家族。其中一些酶在发育或生理过程中发挥作用，如蜕皮激素代谢。然而，对昆虫GMC家族的功能多样性知之甚少。在此，我们在家蚕基因组中发现了43个GMC基因，是迄今为止测序的昆虫基因组中数量最多的。与其他昆虫相似，家蚕fltillin-2(flo-2)基因的第二内含子中有一个高度保守的GMC簇。然而，家蚕的GMC基因在保守的GMC簇之外经历了很大的扩张。系统发育分析表明，家蚕gmcβ亚家族包含22个拷贝，对家蚕gmc基因的扩增有重要贡献。家蚕gmcβ亚家族的22个成员中有18个位于保守的gmc簇之外，称为家蚕扩展基因(Ses)。相对速率检验表明，在保守的GMC簇中，SES的进化速度明显快于GMCβ基因。相应地，SES的第三位GC含量(GC3S)和密码子偏好性与保守GMC簇中的GMCβ基因显著不同。家蚕gmcβ基因在保守的gmc簇外的进化速度提高，可能反映了功能多样性的进化。在43个家蚕GMC基因中，至少有24个在幼虫阶段以组织或阶段特异性的方式差异转录和表达。引人注目的是，微阵列数据显示，四种不同的病原体上调了大部分家蚕gmcβ基因。此外，具有代表性的上调的GMCβ基因的RNA干扰降低了家蚕在病原体感染时的存活率。综上所述，这些结果表明家蚕GMC氧化还原酶基因的扩增与免疫有关。
The glucose-methanol-choline (GMC) oxidoreductases constitute a large gene family in insects. Some of these enzymes play roles in developmental or physiological process, such as ecdysteroid metabolism. However, little is known about the functional diversity of the insect GMC family. Here, we identified 43 GMC genes in the silkworm genome, the largest number of GMC genes among all the insect genomes sequenced to date. Similar to the other insects, there is a highly conserved GMC cluster within the second intron of the silkworm flotillin-2 (flo-2) gene. However, the silkworm GMC genes outside of the conserved GMC cluster have experienced a large expansion. Phylogenetic analysis suggested that the silkworm GMCβ subfamily contained 22 copies and made a major contribution to expansion of the silkworm GMC genes. Eighteen of the 22 members of the silkworm GMCβ subfamily are located outside of the conserved GMC cluster, and are known as silkworm expansion genes (SEs). Relative-rate tests showed that SEs evolved significantly faster than the GMCβ genes inside the conserved GMC cluster. Accordingly, the third position GC content (GC3s) and codon bias of SEs are significantly different from those of the GMCβ genes in the conserved GMC cluster. The elevated evolutionary rate of the silkworm GMCβ genes outside of the conserved GMC cluster may reflect the evolution of function diversity. At least 24 of the 43 silkworm GMC genes were differently transcribed and expressed in a tissue- or stage-specific manner during the larval stage. Strikingly, microarray data revealed that four different pathogens upregulated most of the silkworm GMCβ genes. Furthermore, RNA interference of representative upregulated GMCβ genes reduced the survival rate of the silkworm when infected by pathogens. Taken together, the results suggested that expansion of the silkworm GMC oxidoreductase genes is associated with immunity.