Hemomucin, an O-Glycosylated Protein on Embryos of the Wasp Macrocentrus cingulum That Protects It against Encapsulation by Hemocytes of the Host Ostrinia furnacalis
Hemomucin, an O-Glycosylated Protein on Embryos of the Wasp Macrocentrus cingulum That Protects It against Encapsulation by Hemocytes of the Host Ostrinia furnacalis
复制标题
血粘蛋白，一种黄蜂胚胎上的 O-糖基化蛋白，可保护其免受宿主亚洲玉米螟血细胞的包裹
DOI：
10.1159/000360819
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发表时间：
2014-01-01
影响因子：
5.3
通讯作者：
Zhang, Wenqing
中科院分区：
文献类型：
--
作者：
Hu, Jian;Xu, Qiuyun;Zhang, Wenqing
目前尚不清楚在大多数寄生虫-宿主系统中，体内寄生虫如何被动地逃避宿主的免疫反应。血粘蛋白（Hemomucin，McHEM）是一种分子量为97 kDa的跨膜蛋白，含有51个糖基化位点，能被花生凝集素特异性识别。Mchem mRNA在M. McHEM蛋白主要定位于胚胎的胚外膜上。M.将带瓣移植到其宿主Ostriniapeacalis的幼稚幼虫中，胚胎增殖产生数十个胚胎。然而，超过90%的这些胚胎被宿主血细胞包裹后，用抗McHEM血清封闭。类似地，在使用编码Mchem的双链RNA（dshem）敲低Mchem表达后，与对照相比，移植后更多的胚胎被宿主血细胞包封（p < 0.01）。此外，约70%的胚胎在O-糖苷酶消化后被宿主血细胞包裹，O-糖苷酶特异性地破坏GalNAc和蛋白质的Ser/Thr之间的β-gal（1→3）键。Western blotting结果表明O-糖苷酶能将McHEM酶解成较小的产物。这些结果表明，McHEM可以保护胚胎免受其宿主的包囊，McHEM糖链起着重要作用。
It is unclear how endoparasites passively evade their host's immune reactions in most parasite-host systems. Hemomucin from the parasitoid wasp Macrocentrus cingulum (McHEM) is a 97-kDa transmembrane protein containing 51 potential O-glycosylation sites that can be specifically recognized by Arachis hypogaea lectin. Mchem mRNA is highly expressed in M. cingulum eggs, morulae and secondary embryos, and McHEM protein is mainly located on the extraembryonic membrane of embryos. When secondary embryos of M. cingulum were transplanted into naïve larvae of their host, Ostrinia furnacalis, the embryos proliferated to generate dozens of embryos. However, more than 90% of these embryos were encapsulated by host hemocytes after blocking with anti-McHEM serum. Similarly, following knockdown of Mchem expression using double-stranded RNA encoding Mchem (dshem), many more embryos were encapsulated by host hemocytes after transplantation compared to controls (p < 0.01). Furthermore, approximately 70% of the embryos were encapsulated by host hemocytes following digestion with O-glycosidase, which specifically digests β-gal (1→3) linkages between GalNAc and Ser/Thr of proteins. Western blotting results showed that O-glycosidase digested McHEM into a smaller product. These results indicate that McHEM may protect embryos from being encapsulated by their host and that the McHEM sugar chains play an important role.