Cathepsin L is Involved in Cellular Immune Response and Induced by Ecdysone in Helicoverpa armigera
ZHANG Xin, JI Hongli, ZHANG Shisong, MA Ruying, WANG Gang*
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.
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