A viral histone H4 suppresses expression of a transferrin that plays a role in the immune response of the diamondback moth, Plutella xylostella
A viral histone H4 suppresses expression of a transferrin that plays a role in the immune response of the diamondback moth, Plutella xylostella
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DOI：
10.1111/j.1365-2583.2010.01014.x
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发表时间：
2010-08-01
影响因子：
2.6
通讯作者：
Kim, Y.
中科院分区：
文献类型：
--
作者：
Kim, J.;Kim, Y.
从小菜蛾的一个表达序列标签中预测了一个转铁蛋白基因。它编码681个氨基酸残基，与其他鳞翅目转铁蛋白有80-90%的同源性。该基因在小菜蛾的各个发育阶段均组成型表达。制备特异于Tf基因的双链RNA（dsRNA）并显微注射到幼虫中。我们推测，dsRNA处理抑制Tf基因的表达水平，它显着抑制血细胞结节形成响应细菌的挑战。用dsRNA处理的幼虫还显示出对昆虫病原细菌苏云金芽孢杆菌的敏感性显著增强。菜蛾绒茧蜂（Cotesia plutellae）寄生小菜蛾幼虫后，转铁蛋白表达量显著降低。Tf表达的抑制是通过瞬时表达一个病毒基因CpBV-H4来模拟的，CpBV-H4编码于C. plutellae。通过删除延长的N-末端38个氨基酸残基制备的CpBV-H4的截短形式失去了其对Tf基因表达的抑制活性。这些结果表明，转铁蛋白在小菜蛾体内具有免疫学作用，病毒组蛋白H4以表观遗传方式抑制了其在小菜蛾体内的表达。
A transferrin (Tf) gene has been predicted from an expressed sequence tag of the diamondback moth, Plutella xylostella. It encodes 681 amino acid residues that share 80-90% sequence homologies with other lepidopteran Tfs. The gene was constitutively expressed in all developmental stages of P. xylostella. Double-stranded RNA (dsRNA) specific to the Tf gene was prepared and microinjected into the larvae. We hypothesize that the dsRNA treatment suppressed the Tf gene expression level and it significantly inhibited haemocyte nodule formation in response to bacterial challenge. The larvae treated with dsRNA also showed a significantly enhanced susceptibility to an entomopathogenic bacterium, Bacillus thuringiensis. An endoparasitoid wasp, Cotesia plutellae, parasitized the larvae of P. xylostella, which showed significant reduction of Tf expression. The suppression of Tf expression was mimicked by transient expression of a viral gene CpBV-H4, encoded in the symbiotic virus of C. plutellae. A truncated form of CpBV-H4 prepared by deleting an extended N-terminal 38 amino acid residue lost its inhibitory activity against the Tf gene expression. These results suggest that Tf of P. xylostella plays an immunological role in P. xylostella and that the suppression of its expression in the parasitized larvae is caused by a viral histone H4 in an epigenetic mode.