Takehana Aya, Katsuyama Tomonori, Yano Tamaki, Oshima Yoshiteru, Takada Haruhiko, Aigaki Toshiro, Kurata Shoichiro
Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Proc Natl Acad Sci U S A. 2002 Oct 15;99(21):13705-10. doi: 10.1073/pnas.212301199. Epub 2002 Oct 1.
In Drosophila, microbial infection activates an antimicrobial defense system involving the activation of proteolytic cascades in the hemolymph and intracellular signaling pathways, the immune deficiency (imd) and Toll pathways, in immune-responsive tissues. The mechanisms for microbial recognition are largely unknown. We report that, in larvae, the imd-mediated antibacterial defense is activated by peptidoglycan-recognition protein (PGRP)-LE, a PGRP-family member in Drosophila. Consistent with this, PGRP-LE binds to the diaminopimelic acid-type peptidoglycan, a cell-wall component of the bacteria capable of activating the imd pathway, but not to the lysine-type peptidoglycan. Moreover, PGRP-LE activates the prophenoloxidase cascade, a proteolytic cascade in the hemolymph. Therefore, PGRP-LE acts as a pattern-recognition receptor to the diaminopimelic acid-type peptidoglycan and activates both the proteolytic cascade and intracellular signaling in Drosophila immunity.
在果蝇中，微生物感染会激活一种抗菌防御系统，该系统涉及血淋巴中蛋白水解级联反应的激活以及免疫反应组织中的细胞内信号通路，即免疫缺陷（imd）和Toll通路。微生物识别机制在很大程度上尚不清楚。我们报告称，在幼虫中，imd介导的抗菌防御由肽聚糖识别蛋白（PGRP）-LE激活，PGRP-LE是果蝇中的一种PGRP家族成员。与此一致的是，PGRP-LE与二氨基庚二酸型肽聚糖结合，二氨基庚二酸型肽聚糖是能够激活imd通路的细菌细胞壁成分，但不与赖氨酸型肽聚糖结合。此外，PGRP-LE激活前酚氧化酶级联反应，这是血淋巴中的一种蛋白水解级联反应。因此，PGRP-LE作为二氨基庚二酸型肽聚糖的模式识别受体，并在果蝇免疫中激活蛋白水解级联反应和细胞内信号传导。
