棉铃虫Cathepsin L参与细胞免疫并受蜕皮激素调控

Cathepsin L is Involved in Cellular Immune Response and Induced by Ecdysone in Helicoverpa armigera

半胱氨酸蛋白酶参与昆虫的许多生理过程,但是其调控机制还不完全清楚,该文利用实时定量RT-PCR(qRT-PCR)、免疫组织化学、基因干扰(RNAi)等方法对棉铃虫组织蛋白酶L基因(HacatL)进行了系统研究。结果表明, HacatL在棉铃虫血细胞中的浆血细胞和颗粒细胞中大量表达,在蜕皮和变态时期表达量上升。细菌免疫刺激能明显诱导HacatL的表达上调;在幼虫体内将HacatL基因沉默后能明显降低血细胞的伸展性和对细菌的清除能力。蜕皮激素(20-hydroxyecdysone, 20E)能通过其受体(ecdysone receptor, EcR)及配体蛋白(ultraspiracle, USP)诱导HacatL的表达。这些结果说明HacatL基因受到蜕皮激素信号转导途径调控并参与昆虫细胞免疫反应。该研究结果有助于人们理解蜕皮激素调控昆虫细胞免疫的机制,同时也可为高等动物激素调控免疫反应的研究提供新的思路。

Insect cysteine proteinases play important roles in many physiological processes,but the molecular mechanism is not fully understood.In this study,qRT-PCR(real-time quantitative RT-PCR),immunohistochemistry,RNAi(gene interference)were used to systematically study the cathepsin L proteinase gene(HacatL)in Helicoverpa armigera.The results indicate that HacatL gene is highly expressed in plasmatocytes and granulocytes,and its expression increases during molting and metamorphosis.Bacterial immune stimulation induced the HacatL expression.Silencing of HacatL in vivo significantly increased bacterial load in larval hemolymphs and reduced the plasmatocyte spread.Ecdysone 20E(20-hydroxyecdysone)can induce HacatL expression through its EcR(ecdysone receptor)and its partner USP(ultraspiracle).These results suggest that HacatL gene is regulated by ecdysone signaling pathway and is involved in cellular immune response in insects.This results contribute to the understanding of regulatory mechanism of ecdysone regulating cellular immunity in insects,and also provide new insights into how hormones regulating immune response in mammals.