Expressional induction of Paralichthys olivaceus cathepsin B gene in response to virus, poly I:C and lipopolysaccharide.
Cathepsin B is a lysosomal cysteine protease of the papain-like enzyme family with multiple biological functions. In this study, Paralichthys olivaceus cathepsin B (PoCatB) cDNA was isolated from flounder embryonic cells (FEC) treated with UV-inactivated grass carp hemorrhage virus (GCHV) and subsequently identified as a virally induced gene. The full length cDNA of PoCatB is 1801bp encoding 330-amino acids. The deduced protein has high homology to all known cathepsin B proteins, containing an N-terminal signal peptide, cysteine protease active sites, the occluding loop segment and a glycosylation site, all of which are conserved in the cathepsin B family. PoCatB transcription of FEC cells could be induced by turbot (Scophthalmus maximus) rhabdovirus (SMRV), UV-inactivated SMRV, UV-inactivated GCHV, poly I:C or lipopolysaccharide (LPS), and SMRV or poly I:C was revealed to be most effective among the five inducers. In normal flounder, PoCatB mRNA was detectable in all examined tissues. Moreover, SMRV infection could result in significant upregulation of PoCatB mRNA, predominantly in spleen, head kidney, posterior kidney, intestine, gill and muscle with 18.2, 10.9, 24.7, 12, 31.5 and 18 fold increases at 72h post-infection respectively. These results provided the first evidence for the transcriptional induction of cathepsin B in fish by virus and LPS, indicating existence of a novel function in viral defense.
Zhang
Fu-Tie
FT
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Zhang
Yi-Bing
YB
Chen
Yu-Dong
YD
Zhu
Rong
R
Dong
Cai-Wen
CW
Li
Yang-Yang
YY
Zhang
Qi-Ya
QY
Gui
Jian-Fang
JF