ORIGINAL PAPER Molecular characterization and expression of Rab7 from Clonorchis sinensis and its potential role in autophagy Feifei Jia & Ye Li & Yan Huang & Tingjin Chen & Shan Li & Yanquan Xu & Zhongdao Wu & Xuerong Li & Xinbing Yu Received: 15 March 2013 / Accepted: 21 March 2013 / Published online: 23 April 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Accumulating evidences suggest that Rab7 GTPase is important for the normal progression of autophagy. However, the role of Rab7 GTPase in regulation of auto- phagy in Clonorchis sinensis is not known. In this study, a gene encoding Rab7 was isolated from C. sinensis adult cDNA. Recombinant CsRab7 was expressed and purified from Escherichia coli. CsRab7 transcripts were detected in the cDNA of adult worm, metacercaria, cercaria, and egg of C. sinensis, and were highly expressed in the metacercaria. Immunohistochemical localization results revealed that CsRab7 was specifically deposited on the vitellarium and eggs of adult worm. Furthermore, EGFP signal of CsRab7WT and the active mutant CsRab7Q67L were asso- ciated with autophagic vesicles in transiently transfected 293T cells. It is concluded from the present study that CsRab7 GTPase possibly contributes to the development of C. sinensis and that the autophagy pathway could be an important site of action with respect to the developmental role of CsRab7 in C. sinensis. Introduction Clonorchis sinensis, a pathogenic trematode, is the etiological agent of the human disease known as cholangiocarcinoma, which causes considerable human morbidity and mortality of people worldwide (Young et al. 2010; Shin et al. 2010; Sripa et al. 2007). Moreover, chronic infection by the carcinogenic parasite was responsible for other hepatobiliary diseases such as pyogenic cholangitis, cholelithiasis, cholecystitis, and he- patic fibrosis. Considering the unavailability of an appropriate vaccine, a search is on to study the mechanism of host– pathogen interaction. Autophagy is the main pathway for cytoplasmic component degradation (Eskelinen et al. 2004; Burman and Ktistakis 2010), which is triggered by nutrient deficiency and various stress conditions (Eskelinen and Saftig 2009; Kroemer et al. 2010; Andrade et al. 2006). Mammalian cells use autophagy during short periods of starvation to degrade nonessential cellular components in order to acquire nutrients for energy production and vital biosynthetic reac- tions. Several lines of evidence suggest that the autophagic machinery played a role in several host–pathogen interactions and host defense (Yano et al. 2008; Gutierrez et al. 2004; Ogawa et al. 2005). However, the mechanism underlying autophagic cargo delivery and the interplay between auto- phagosome and lysosome in host–pathogen interaction is not known. Small GTP binding protein Rab7 has a role in the final maturation of late autophagic vacuoles in mammalian cells (Jager et al. 2004; Lin et al. 2012) and degradation of endocytosed hemoglobin for Leishmania growth (Patel et al. 2008). Moreover, Rab7 is dispensable in GAS-containing autophagosome-like vacuole formation (Yamaguchi et al. 2009). Although Rab7 proteins are present in parasites, their Electronic supplementary material The online version of this article (doi:10.1007/s00436-013-3409-0) contains supplementary material, which is available to authorized users. F. Jia : Y. Li : Y. Huang : T. Chen : S. Li : Y. Xu : Z. Wu : X. Li : X. Yu Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China F. Jia : Y. Li : Y. Huang : T. Chen : S. Li : Y. Xu : Z. Wu : X. Li (*) : X. Yu (*) Key Laboratory of Tropical Disease Control, Ministry of Education, Guangzhou 510080, China e-mail: prlab@mail.sysu.edu.cn e-mail: yuhxteam@163.com Parasitol Res (2013) 112:2461–2467 DOI 10.1007/s00436-013-3409-0