Activation of the silkworm cytokine by bacterial and fungal cell wall components via a reactive oxygen species-triggered mechanism
Activation of the silkworm cytokine by bacterial and fungal cell wall components via a reactive oxygen species-triggered mechanism
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DOI：
10.1074/jbc.m705480200
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发表时间：
2008-01-25
影响因子：
4.8
通讯作者：
Sekimizu, Kazuhisa
中科院分区：
文献类型：
--
作者：
Ishii, Kenichi;Hamamoto, Hiroshi;Sekimizu, Kazuhisa
昆虫细胞因子麻痹肽（PP）可诱导蚕蛹肌肉收缩。在这里，我们证明了细菌和真菌细胞壁成分肽聚糖和葡聚糖通过激活血淋巴中的PP来刺激肌肉收缩。抗PP抗体抑制PP、肽聚糖或葡聚糖引起的肌肉收缩。自由基清除剂和丝氨酸蛋白酶抑制剂也能抑制收缩。此外，给活蚕注射肽聚糖或葡聚糖可产生活性形式的PP。将肽聚糖或葡聚糖与含有PP前体的血淋巴孵育也可在体外产生活性形式的PP。自由基清除剂和丝氨酸蛋白酶抑制剂抑制活性形式PP的产生。此外，在分离的血淋巴中，PP活化被氰化钾抑制，这表明细胞活性参与其中。肽聚糖刺激可促进家蚕血细胞产生活性氧。在家蚕幼虫中加入活性形式的PP或抗PP抗体，分别延缓或增强了金黄色葡萄球菌的杀伤作用，表明活化的PP有助于宿主抵抗感染性病原体。这些发现表明，肽聚糖或葡聚糖等免疫刺激物诱导幼虫血细胞产生活性氧，随后激活丝氨酸蛋白酶，介导PP加工反应并导致防御反应。
The insect cytokine paralytic peptide ( PP) induces muscle contraction in silkworm larvae. Here we demonstrate that bacterial and fungal cell wall components peptidoglycan and glucan stimulate muscle contraction via activation of PP in the hemolymph. Anti-PP antibody suppressed the muscle contraction induced by PP, peptidoglycan, or glucan. The contraction was also inhibited by free radical scavengers and serine protease inhibitors. Moreover, injecting live silkworms with peptidoglycan or glucan generated the active form of PP. The active form of PP was also produced in vitro when peptidoglycan or glucan was incubated with hemolymph containing the PP precursor. Generation of the active form of PP was suppressed by free radical scavengers and serine protease inhibitors. Furthermore, PP activation in isolated hemolymph was inhibited by potassium cyanide, suggesting that cellular activity is involved. Stimulation by peptidoglycan promoted the generation of reactive oxygen species by silkworm hemocytes. The addition of either the active form of PP or anti-PP antibody to Staphylococcus aureus injected into silkworm larvae delayed or enhanced, respectively, the killing effect of S. aureus, suggesting that activated PP contributes to host resistance to infectious pathogens. These findings suggest that immunologic stimulants such as peptidoglycan or glucan induce reactive oxygen species production from larval hemocytes, followed by the activation of serine protease, which mediates the PP processing reaction and leads to defensive responses.