Phosvitin Plays a Critical Role in the Immunity of Zebrafish Embryos via Acting as a Pattern Recognition Receptor and an Antimicrobial Effector*
Phosvitin Plays a Critical Role in the Immunity of Zebrafish Embryos via Acting as a Pattern Recognition Receptor and an Antimicrobial Effector*
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DOI：
10.1074/jbc.m111.247635
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发表时间：
2011-04
期刊：
影响因子：
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通讯作者：
Shaohui Wang;Yuan-Zhao Wang;Jie Ma;Yunchao Ding;Shicui Zhang
中科院分区：
文献类型：
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作者：
Shaohui Wang;Yuan-Zhao Wang;Jie Ma;Yunchao Ding;Shicui Zhang
外部发育的鱼类胚胎如何在微生物的攻击下存活，人们知之甚少。在这里，我们清楚地表明，斑马鱼胚胎提取物及其早期胚胎都显示出对微生物的抗菌活性，包括致病性气单胞菌，以及卵中丰富的营养蛋白--卵清蛋白（Pv），与这种抗菌活性有关。我们还发现，重组Pv（rPv）作为一种模式识别受体，能够识别微生物标记分子LPS，脂磷壁酸和肽聚糖，以及结合革兰氏阴性和阳性微生物大肠杆菌，A。金黄色葡萄球菌和金黄色葡萄球菌，并作为能够杀死微生物的抗菌剂发挥作用。此外，我们发现，其C-末端55个残基（Pt 5）的功能位点Arg 242和Ala 201/Ile 203是必不可少的Pv抗菌活性。重要的是，显微注射rPv或Pt 5到早期胚胎中显著增强了它们对A.抗-Pv抗体与rPv（或Pt 5）联合注射可显著降低细菌的耐药性，而抗-肌动蛋白抗体与rPv联合注射则无此作用。此外，所产生的具有体外抑菌活性的突变体，当注射到胚胎中时，也可以促进它们对A.而那些没有体外抗菌活性的则不能。因此，Pv通过结合和破坏潜在的病原体参与保护早期胚胎免受病原体攻击。这项工作也为研究依赖卵黄蛋白进行胚胎发育的卵生动物卵黄蛋白的免疫作用开辟了新的途径。
How fish embryos that develop externally survive microbial attacks is poorly understood. Here, we clearly demonstrated that the embryo extract of zebrafish and its early embryo both displayed antimicrobial activity against microbes, including pathogenic Aeromonas hydrophila, and phosvitin (Pv), a nutritional protein abundant in eggs, was related to this antimicrobial activity. We also showed that recombinant Pv (rPv) acted as a pattern recognition receptor capable of recognizing the microbial signature molecules LPS, lipoteichoic acid, and peptidoglycan, as well as binding the Gram-negative and -positive microbes Escherichia coli, A. hydrophila, and Staphylococcus aureus and functioned as an antimicrobial agent capable of killing the microbes. Furthermore, we revealed that its C-terminal 55 residues (Pt5) with the functional sites Arg242 and Ala201/Ile203 were indispensable for Pv antimicrobial activity. Importantly, microinjection of rPv or Pt5 into early embryos significantly enhanced their resistance to A. hydrophila challenge, and this enhanced bacterial resistance was markedly reduced by co-injection of anti-Pv antibody plus rPv (or Pt5) but not by injection of anti-actin antibody plus rPv. Moreover, the generated mutants with in vitro antimicrobial activity, when injected into the embryos, could also promote their resistance to A. hydrophila, but those without in vitro antimicrobial activity could not. It is thus proposed that Pv participates in the protection of early embryos against pathogenic attacks via binding and disrupting potential pathogens. This work also opens a new way for the study of the immunological roles of yolk proteins in oviparous animals that rely on yolk proteins for embryonic development.