In vivo regulation of GLUT2 mRNA in sea bass (Dicentrarchus labrax) in response to acute and chronic hypoxia.
The expression and regulation of sodium-independent glucose transporter (GLUT)-2, in relation to hypoxia has not yet been explored in fish or other vertebrates. In this study, the complete open-reading frame for sea bass GLUT2 was isolated and deposited in the GenBank. The predicted 12 transmembrane domains of the protein (508 amino acids) are presented. A phylogenetic tree was constructed on GLUT2 sequences of sea bass and those of other teleost, amphibian, avian, and mammalian species. We also analyzed acute and chronic hypoxia-induced changes in the expression of hepatic GLUT2 mRNA, using one-tube, two-temperature, real-time RT-PCR with which gene expression can be absolutely quantified by the standard curve method. The number of GLUT2 mRNA copies was significantly increased in response to both acute (1.9 mg/L, dissolved oxygen for 4 h) and chronic (4.3 mg/L, DO for 15 days) hypoxia conditions. The hypoxia-related changes in GLUT2 mRNA copy number support the view that GLUT2 is involved in the adaptation response to hypoxia in sea bass, a marine hypoxia-sensitive species. We realize that the GLUT2 mRNA levels in our study do not measure the physiological effects produced by the protein. Thus, we can only speculate that, under hypoxic conditions, GLUT2 probably functions to allow the glucose produced from liver glycogen to leave the hepatocytes.
Terova
Genciana
G
Department of Biotechnology and Molecular Sciences, University of Insubria, Varese, Italy. genciana.terova@uninsubria.it
Rimoldi
Simona
S
Brambilla
Fabio
F
Gornati
Rosalba
R
Bernardini
Giovanni
G
Saroglia
Marco
M
D000208:Acute Disease; D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass / Q000235:genetics*; D002908:Chronic Disease; D003001:Cloning, Molecular; D005393:Fish Diseases / Q000235:genetics* / Q000473:pathology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics*; D051273:Glucose Transporter Type 2 / Q000235:genetics* / Q000378:metabolism*; D000860:Hypoxia / Q000235:genetics / Q000662:veterinary*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
D051273:Glucose Transporter Type 2; D012333:RNA, Messenger