title: Molecular cloning and characterization of cystatin, a cysteine protease inhibitor, from Angiostrongylus cantonensis.
abstract: Cystatins are thiol proteinase inhibitors ubiquitously present in mammalian body and serve various important physiological functions. In the present study, a novel cystatin molecule (AcCystatin) was cloned from a cDNA library of Angiostrongylus cantonensis fourth-stage larvae. The putative 14-kDa protein contained 120 residues with cystatin-conserved motifs known to interact with the active site of cysteine peptidases and showed high identities with cystatins from other nematodes. RT-PCR analysis revealed that the expression pattern of AcCystatin was equal at the time points of third-stage larvae, fourth-stage larvae, and adults of the parasite life cycle. The recombinant AcCystatin (rAcCystatin) expressed and purified from Escherichia coli has been demonstrated to possess an obvious inhibitory activity against cathepsin B and could significantly upregulate nitric oxide production from IFN-gamma activated RAW 264.7 macrophages. Sera from mice (non-permissive host) infected with A. cantonensis detected rAcCystatin by Western blot, while the sera from infected rats (permissive host) could not. The results implied that AcCystatin might be an immunoregulator in A. cantonensis infection.
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 2nd Zhongshan Road, Guangzhou, 510080, China.
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Liu
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Han
authors.forename: Zheng-Yu
authors.initials: ZY
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Wei
authors.forename: Han-Jiang
authors.initials: HJ
authors.lastname: He
authors.forename: Chang-Zhi
authors.initials: CZ
authors.lastname: Xu
authors.forename: Huan-Qin
authors.initials: HQ
authors.lastname: Zheng
authors.forename: Xi-Mei
authors.initials: XM
authors.lastname: Zhan
authors.forename: Zhong-Dao
authors.initials: ZD
authors.lastname: Wu
authors.forename: Zhi-Yue
authors.initials: ZY
authors.lastname: Lv
mesh_terms: D020816:Amino Acid Motifs; D017185:Angiostrongylus cantonensis / Q000201:enzymology* / Q000235:genetics*; D000818:Animals; D002401:Cathepsin B / Q000037:antagonists & inhibitors; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D015891:Cystatins / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D017206:Strongylida Infections / Q000469:parasitology
chemical_list: D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D015801:Helminth Proteins; D011994:Recombinant Proteins; D009569:Nitric Oxide; D002401:Cathepsin B