Activation of Insect Phenoloxidase after Injury: Endogenous versus Foreign Elicitors
Activation of Insect Phenoloxidase after Injury: Endogenous versus Foreign Elicitors
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DOI：
10.1159/000168009
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发表时间：
2009-01-01
影响因子：
5.3
通讯作者：
Theopold, Ulrich
中科院分区：
文献类型：
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作者：
Bidla, Gawa;Hauling, Thomas;Theopold, Ulrich
酚氧化酶(PO)是在无脊椎动物中发现的最早的免疫分子之一。近年来，PO的免疫功能受到挑战。我们测试了两种昆虫，即果蝇和蜡蛾在受伤后PO是如何被激活的。果蝇体内PO的快速激活仅限于损伤后形成的血淋巴凝块的离散区域。令人惊讶的是，与细菌败血症时全身PO的激活不同，在我们的实验中，凝块黑化对微生物激发子不敏感。相反，果蝇凝块黑化是由内源性信号激活的，如凋亡细胞，并被磷脂酰丝氨酸超诱导，磷脂酰丝氨酸是一种带负电荷的磷脂，通常存在于质膜内表面，并在凋亡期间暴露。相比之下，梅氏革兰氏菌血淋巴的黑化更强烈和更均匀，对肽聚糖敏感。这表明，外源和内源信号都可以通过物种和上下文依赖的方式触发相同的免疫机制。我们的发现对免疫机制的进化动力学有影响，并与最近对昆虫免疫转录本的比较一致。版权所有(C)2008 S.Karger AG，巴塞尔
The enzyme phenoloxidase (PO) is one of the first immune molecules that was identified in invertebrates. Recently, the immune function of PO has been challenged. We tested how PO is activated following injury in 2 insects, i.e. the fruit fly Drosophila melanogaster and the wax moth Galleria mellonella. Rapid PO activation in Drosophila was limited to discrete areas of the hemolymph clot which forms after injury. Surprisingly, unlike systemic PO activation during bacterial sepsis, clot melanization was not sensitive to microbial elicitors in our assay. Instead, Drosophila clot melanization was activated by endogenous signals such as apoptotic cells and was superinduced by phosphatidylserine, a negatively charged phospholipid normally found on the inner surface of the plasma membrane and exposed during apoptosis. In contrast, melanization in G. mellonella hemolymph was stronger and more uniform and was sensitive to peptidoglycan. This shows that both exogenous and endogenous signals can trigger the same immune mechanism in species and context-dependent ways. Our findings have implications for the evolutionary dynamics of immune mechanisms and are in agreement with recent comparisons of insect immune transcriptomes. Copyright (C) 2008 S. Karger AG, Basel