PMID- 17045849
OWN - NLM
STAT- MEDLINE
DCOM- 20070126
LR  - 20201209
IS  - 1532-0456 (Print)
IS  - 1532-0456 (Linking)
VI  - 144
IP  - 3
DP  - 2006 Nov
TI  - Structural and functional characterization of microcystin detoxification-related 
      liver genes in a phytoplanktivorous fish, Nile tilapia (Oreochromis niloticus).
PG  - 216-27
AB  - Liver genes related to phase I and phase II detoxification, as well as inhibition 
      of reactive oxygen species (ROS) production, were cloned, and their response to 
      microcystin-LR (MC-LR) and lipopolysaccharide (LPS) exposure via intraperitoneal 
      injection, was determined in a phytoplanktivorous fish, Nile tilapia (Oreochromis 
      niloticus). The cloned full-length cDNA of tilapia soluble glutathione 
      S-transferase (sGST) was classified as alpha-class GST based on their amino acid 
      sequence identity with other species. The tilapia sGST clone was 861 bp in 
      length, and contained a 25 bp 5'-UTR, a 167 bp 3'-UTR and an open reading frame 
      of 669 bp, encoding a polypeptide of 222 amino acids. Using genome walker method, 
      a 366 bp 5'-flanking sequence of tilapia sGST gene was further obtained, and the 
      possible regulatory elements were identified. Partial cDNA sequences of 
      glutathione peroxidase (GPX) and uncoupling protein 2 (UCP2) were also obtained 
      by PCR using degenerate primers from tilapia liver. To study the transcriptional 
      response of liver genes to microcystin treatment, tilapia were respectively 
      exposed to a single 50 microg kg(-1) body weight (bwt) dose of pure MC-LR, a 
      single 2 mg kg(-1) bwt dose of LPS and a co-exposure MC-LR and LPS (50 microg 
      kg(-1) bwt+2 mg kg(-1) bwt), and were then sacrificed at 24 h post-exposure. 
      Using beta-actin as external control, a significant increase (about 80%) in sGST 
      mRNA expression was found in response to the MC-LR exposure after 24 h (P < 
      0.05), indicating the importance of sGST in microcystin detoxification. A slight 
      decrease of sGST mRNA expression was observed in the liver of tilapia, exposed to 
      LPS and MC-LR+LPS. It seems that the LPS response element (LPSRE), identified in 
      the promoter region of tilapia sGST gene, may be functional at a rather low 
      level. In contrast, the levels of cytochrome P450 1A (CYP1A) mRNA expression were 
      found to keep unchanged to either MC-LR, or LPS, or MC-LR+LPS treatment, 
      indicating that unlike the phase II enzyme (sGST), the phase I enzyme (CYP1A) 
      might not play an important role in the detoxification process of microcystins. 
      Although not significant, the mRNA expression level of GPX tended to increase in 
      the liver of tilapia exposed to both MC-LR and LPS (P > 0.05). In addition, a 
      significant increase in UCP2 mRNA expression was observed in the liver of tilapia 
      exposed to LPS (P < 0.05), as well as an obvious but not significant increase in 
      MC-LR exposure group. We suggest that phase II detoxification enzyme, instead of 
      phase I detoxification enzyme, might be responsible for the strong tolerance of 
      the phytoplanktivorous fish to microcystins, and hepatocyte proteins coping with 
      oxidative stress (GPX and UCP2), might also have some auxiliary effect. In 
      addition, the rather low and insignificant response of tilapia sGST gene to the 
      inhibitory effect of LPS exposure, might possibly be critical to the 
      phytoplanktivorous fish to utilize toxic blue-green algae.
FAU - Wang, Lin
AU  - Wang L
AD  - College of Life Science and Technology, Jinan University, Shipai, Guangzhou 
      510632, China. tliangxf@jnu.edu.cn
FAU - Liang, Xu-Fang
AU  - Liang XF
FAU - Liao, Wan-Qin
AU  - Liao WQ
FAU - Lei, La-Mei
AU  - Lei LM
FAU - Han, Bo-Ping
AU  - Han BP
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20060903
PL  - United States
TA  - Comp Biochem Physiol C Toxicol Pharmacol
JT  - Comparative biochemistry and physiology. Toxicology & pharmacology : CBP
JID - 100959500
RN  - 0 (Carcinogens)
RN  - 0 (DNA, Complementary)
RN  - 0 (Ion Channels)
RN  - 0 (Lipopolysaccharides)
RN  - 0 (Marine Toxins)
RN  - 0 (Microcystins)
RN  - 0 (Mitochondrial Proteins)
RN  - 0 (Uncoupling Protein 2)
RN  - 63231-63-0 (RNA)
RN  - EC 1.11.1.9 (Glutathione Peroxidase)
RN  - EC 2.5.1.18 (Glutathione Transferase)
RN  - EQ8332842Y (cyanoginosin LR)
RN  - GAN16C9B8O (Glutathione)
SB  - IM
MH  - 5' Flanking Region/genetics
MH  - Amino Acid Sequence
MH  - Animals
MH  - Base Sequence
MH  - Carcinogens/*metabolism
MH  - Cloning, Molecular
MH  - DNA, Complementary/genetics
MH  - Glutathione/metabolism
MH  - Glutathione Peroxidase/metabolism
MH  - Glutathione Transferase/genetics/metabolism
MH  - Inactivation, Metabolic/*genetics/*physiology
MH  - Ion Channels/metabolism
MH  - Lipopolysaccharides/pharmacology
MH  - Liver/*metabolism
MH  - Marine Toxins
MH  - Microcystins/*metabolism
MH  - Mitochondrial Proteins/metabolism
MH  - Molecular Sequence Data
MH  - Oxidative Stress/drug effects
MH  - *Phytoplankton
MH  - RNA/biosynthesis/isolation & purification
MH  - Reverse Transcriptase Polymerase Chain Reaction
MH  - Tilapia/*metabolism
MH  - Uncoupling Protein 2
EDAT- 2006/10/19 09:00
MHDA- 2007/01/27 09:00
CRDT- 2006/10/19 09:00
PHST- 2006/03/29 00:00 [received]
PHST- 2006/08/18 00:00 [revised]
PHST- 2006/08/28 00:00 [accepted]
PHST- 2006/10/19 09:00 [pubmed]
PHST- 2007/01/27 09:00 [medline]
PHST- 2006/10/19 09:00 [entrez]
AID - S1532-0456(06)00196-7 [pii]
AID - 10.1016/j.cbpc.2006.08.009 [doi]
PST - ppublish
SO  - Comp Biochem Physiol C Toxicol Pharmacol. 2006 Nov;144(3):216-27. doi: 
      10.1016/j.cbpc.2006.08.009. Epub 2006 Sep 3.