Abstract
Perfusion of rat jejunum in vitro with PMA increased fructose transport by 70% compared with control values and was blocked by the protein kinase C (PKC) inhibitor chelerythrine. The brush-border membrane contained both the fructose transporters GLUT5 and GLUT2; the presence of the latter was confirmed by luminal biotinylation. PMA increased the GLUT2 level 4-fold within minutes, so that the level was comparable with that of the basolateral membrane, but had no effect on GLUT5 level. GLUT2 was functional, accessible to luminal fructose and could be inhibited selectively by phloretin to permit determination of GLUT2- and GLUT5-mediated transport components. The 4-fold increase in GLUT2 level induced by PMA was matched by a 4-fold increase in GLUT2-mediated transport: there was a compensatory fall in the GLUT5-mediated rate. The pattern of dynamic trafficking was seen only for GLUT2, not GLUT5 or SGLT1, implying that GLUT2 trafficks to the brush-border membrane by a different pathway. Trafficking of GLUT2 to the brush-border membrane correlated with activation of PKC betaII, implying that this isoenzyme is likely to control trafficking. Since PKC is activated by endogenous hormones, GLUT2 levels in vivo are 3-4-fold those in vitro; moreover, because PKC is inactivated as soon as intestine is excised, GLUT2 is lost from the brush-border within minutes in vitro. It is therefore difficult to detect GLUT2 in most in vitro preparations and its role in intestinal sugar absorption across the brush-border membrane has accordingly been overlooked.
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Selected References
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- Cheeseman C. I. GLUT2 is the transporter for fructose across the rat intestinal basolateral membrane. Gastroenterology. 1993 Oct;105(4):1050–1056. doi: 10.1016/0016-5085(93)90948-c. [DOI] [PubMed] [Google Scholar]
- Corpe C. P., Basaleh M. M., Affleck J., Gould G., Jess T. J., Kellett G. L. The regulation of GLUT5 and GLUT2 activity in the adaptation of intestinal brush-border fructose transport in diabetes. Pflugers Arch. 1996 Jun;432(2):192–201. doi: 10.1007/s004240050124. [DOI] [PubMed] [Google Scholar]
- Crouzoulon G., Korieh A. Fructose transport by rat intestinal brush border membrane vesicles. Effect of high fructose diet followed by return to standard diet. Comp Biochem Physiol A Comp Physiol. 1991;100(1):175–182. doi: 10.1016/0300-9629(91)90203-o. [DOI] [PubMed] [Google Scholar]
- Davidson N. O., Hausman A. M., Ifkovits C. A., Buse J. B., Gould G. W., Burant C. F., Bell G. I. Human intestinal glucose transporter expression and localization of GLUT5. Am J Physiol. 1992 Mar;262(3 Pt 1):C795–C800. doi: 10.1152/ajpcell.1992.262.3.C795. [DOI] [PubMed] [Google Scholar]
- Ganesan S., Calle R., Zawalich K., Smallwood J. I., Zawalich W. S., Rasmussen H. Glucose-induced translocation of protein kinase C in rat pancreatic islets. Proc Natl Acad Sci U S A. 1990 Dec;87(24):9893–9897. doi: 10.1073/pnas.87.24.9893. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Helliwell P. A., Richardson M., Affleck J., Kellett G. L. Regulation of GLUT5, GLUT2 and intestinal brush-border fructose absorption by the extracellular signal-regulated kinase, p38 mitogen-activated kinase and phosphatidylinositol 3-kinase intracellular signalling pathways: implications for adaptation to diabetes. Biochem J. 2000 Aug 15;350(Pt 1):163–169. [PMC free article] [PubMed] [Google Scholar]
- Kellett G. L., Barker E. D. The effect of vanadate on glucose transport and metabolism in rat small intestine. Biochim Biophys Acta. 1989 Mar 13;979(3):311–315. doi: 10.1016/0005-2736(89)90250-2. [DOI] [PubMed] [Google Scholar]
- Kellett G. L., Helliwell P. A. The diffusive component of intestinal glucose absorption is mediated by the glucose-induced recruitment of GLUT2 to the brush-border membrane. Biochem J. 2000 Aug 15;350(Pt 1):155–162. [PMC free article] [PubMed] [Google Scholar]
- Kellett G. L., Jamal A., Robertson J. P., Wollen N. The acute regulation of glucose absorption, transport and metabolism in rat small intestine by insulin in vivo. Biochem J. 1984 May 1;219(3):1027–1035. doi: 10.1042/bj2191027. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mellor H., Parker P. J. The extended protein kinase C superfamily. Biochem J. 1998 Jun 1;332(Pt 2):281–292. doi: 10.1042/bj3320281. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pennington A. M., Corpe C. P., Kellett G. L. Rapid regulation of rat jejunal glucose transport by insulin in a luminally and vascularly perfused preparation. J Physiol. 1994 Jul 15;478(Pt 2):187–193. doi: 10.1113/jphysiol.1994.sp020241. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Saxon M. L., Zhao X., Black J. D. Activation of protein kinase C isozymes is associated with post-mitotic events in intestinal epithelial cells in situ. J Cell Biol. 1994 Aug;126(3):747–763. doi: 10.1083/jcb.126.3.747. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sharp P. A., Debnam E. S. The role of cyclic AMP in the control of sugar transport across the brush-border and basolateral membranes of rat jejunal enterocytes. Exp Physiol. 1994 Mar;79(2):203–214. doi: 10.1113/expphysiol.1994.sp003753. [DOI] [PubMed] [Google Scholar]
- Sigrist-Nelson K., Hopfer U. A distinct D-fructose transport system in isolated brush border membrane. Biochim Biophys Acta. 1974 Oct 29;367(2):247–254. doi: 10.1016/0005-2736(74)90047-9. [DOI] [PubMed] [Google Scholar]
- Thorens B., Cheng Z. Q., Brown D., Lodish H. F. Liver glucose transporter: a basolateral protein in hepatocytes and intestine and kidney cells. Am J Physiol. 1990 Dec;259(6 Pt 1):C279–C285. doi: 10.1152/ajpcell.1990.259.2.C279. [DOI] [PubMed] [Google Scholar]
- Wollen N., Kellett G. L. Regulation of glucose homeostasis in rat jejunum by despentapeptide-insulin in vitro. Gut. 1988 Aug;29(8):1064–1069. doi: 10.1136/gut.29.8.1064. [DOI] [PMC free article] [PubMed] [Google Scholar]