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Cathepsin L function in insect moulting: molecular cloning and functional analysis in cotton bollworm, Helicoverpa armigera

Authors

  • J. Liu,

    1. Department of Molecular and Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China;
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  • G.-P. Shi,

    1. Department of Molecular and Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China;
    2. The Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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  • W.-Q. Zhang,

    1. State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Zhongshan University, Guangzhou, China;
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  • G.-R. Zhang,

    1. State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Zhongshan University, Guangzhou, China;
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  • W.-H. Xu

    1. State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Zhongshan University, Guangzhou, China;
    2. Department of Molecular and Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China;
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  • doi: 10.1111/j.1365-2583.2006.00686.x

Dr Wei-Hua Xu, State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Zhongshan (or Sun Yat-Sen) University, Guangzhou 510275, China. Tel.: +86 20 84110265; fax: +86 20 84112297; e-mail: xuweihua@mail.sysu.edu.cn

Abstract

Moulting is an essential process of insect development but little is known about cysteine proteases in the process. Here, we detail a proteolytic activity profile from fifth larval instar to new pupae of the lepidopteran Helicoverpa armigera. At fifth to sixth instar moulting, the activities were significantly higher than those in non-moulting stages, and were inhibited by the cysteine protease inhibitor, 2S, 3S-trans-epoxysuccinyl-L-leucylamido-3-methylbutane ethyl ester (E-64), or by the cathepsin L-selective inhibitor CLIK148. Further, a 1513 bp cathepsin L cDNA (Har-CL) was isolated from the H. armigera larval cuticle and epidermis layer. Har-CL gene expression, which is correlated closely with ecdysone, was higher during larval moulting. Injection of E-64 or CLIK148 resulted in delayed fifth to sixth instar moulting, suggesting an essential role for cathepsin L in larval moulting.

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