Skip to main content
PMC home page
The Journal of Clinical Investigation logoLink to The Journal of Clinical Investigation
. 1994 Oct;94(4):1616–1620. doi: 10.1172/JCI117503

Regulatory effects of glucose on the catalytic activity and cellular content of glucokinase in the pancreatic beta cell. Study using cultured rat islets.

C Chen 1, H Hosokawa 1, L M Bumbalo 1, J L Leahy 1
PMCID: PMC295321  PMID: 7929837

Abstract

Glucose regulates the cellular content of glucokinase in the pancreatic beta cell by altering the level of the enzyme. We investigated the existence of a second regulatory pathway, an alteration in the catalytic activity, by comparing Vmax and protein levels of glucokinase in rat islets cultured under high glucose conditions (16.7 mM) for 6, 14, and 24 h. The Vmax was increased by glucose at all time points. In contrast, glucokinase protein levels on Western blots were unchanged from the control value at 6 h but increased 40% at the later time points (P < 0.0002). Further evidence for a dual regulatory system was obtained with a reversal protocol. After a 6-h incubation at high glucose, an additional 3-h incubation at 5.5 mM glucose restored glucokinase Vmax to normal, but failed to change the Vmax after a 24-h incubation at high glucose. Finally, 10 microM cycloheximide partially prevented the increase in glucokinase Vmax induced by 24 h of high glucose, but had no effect at 6 h, suggesting the early increase in enzymatic activity did not require protein synthesis. In summary, glucose regulates both the catalytic activity and cellular content of glucokinase in the beta cell. Glucose-induced increases in glucokinase activity are an important element of the beta cell adaptive response to hyperglycemia.

Full text

PDF
1618

Images in this article

1618Image
on p.1618
1620Image
on p.1620

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Albano J. D., Ekins R. P., Maritz G., Turner R. C. A sensitive, precise radioimmunoassay of serum insulin relying on charcoal separation of bound and free hormone moieties. Acta Endocrinol (Copenh) 1972 Jul;70(3):487–509. doi: 10.1530/acta.0.0700487. [DOI] [PubMed] [Google Scholar]
  2. Buchanan T. A., Youn J. H., Campese V. M., Sipos G. F. Enhanced glucose tolerance in spontaneously hypertensive rats. Pancreatic beta-cell hyperfunction with normal insulin sensitivity. Diabetes. 1992 Jul;41(7):872–878. doi: 10.2337/diab.41.7.872. [DOI] [PubMed] [Google Scholar]
  3. Burch P. T., Trus M. D., Berner D. K., Leontire A., Zawalich K. C., Matschinsky F. M. Adaptation of glycolytic enzymes: glucose use and insulin release in rat pancreatic islets during fasting and refeeding. Diabetes. 1981 Nov;30(11):923–928. doi: 10.2337/diab.30.11.923. [DOI] [PubMed] [Google Scholar]
  4. Chen C., Bumbalo L., Leahy J. L. Increased catalytic activity of glucokinase in isolated islets from hyperinsulinemic rats. Diabetes. 1994 May;43(5):684–689. doi: 10.2337/diab.43.5.684. [DOI] [PubMed] [Google Scholar]
  5. Chen C., Hosokawa H., Bumbalo L. M., Leahy J. L. Mechanism of compensatory hyperinsulinemia in normoglycemic insulin-resistant spontaneously hypertensive rats. Augmented enzymatic activity of glucokinase in beta-cells. J Clin Invest. 1994 Jul;94(1):399–404. doi: 10.1172/JCI117335. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Froguel P., Zouali H., Vionnet N., Velho G., Vaxillaire M., Sun F., Lesage S., Stoffel M., Takeda J., Passa P. Familial hyperglycemia due to mutations in glucokinase. Definition of a subtype of diabetes mellitus. N Engl J Med. 1993 Mar 11;328(10):697–702. doi: 10.1056/NEJM199303113281005. [DOI] [PubMed] [Google Scholar]
  7. Gotoh M., Maki T., Satomi S., Porter J., Bonner-Weir S., O'Hara C. J., Monaco A. P. Reproducible high yield of rat islets by stationary in vitro digestion following pancreatic ductal or portal venous collagenase injection. Transplantation. 1987 May;43(5):725–730. doi: 10.1097/00007890-198705000-00024. [DOI] [PubMed] [Google Scholar]
  8. Hughes J. H., Colca J. R., Easom R. A., Turk J., McDaniel M. L. Interleukin 1 inhibits insulin secretion from isolated rat pancreatic islets by a process that requires gene transcription and mRNA translation. J Clin Invest. 1990 Sep;86(3):856–863. doi: 10.1172/JCI114785. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Hughes S. D., Quaade C., Johnson J. H., Ferber S., Newgard C. B. Transfection of AtT-20ins cells with GLUT-2 but not GLUT-1 confers glucose-stimulated insulin secretion. Relationship to glucose metabolism. J Biol Chem. 1993 Jul 15;268(20):15205–15212. [PubMed] [Google Scholar]
  10. Iynedjian P. B. Mammalian glucokinase and its gene. Biochem J. 1993 Jul 1;293(Pt 1):1–13. doi: 10.1042/bj2930001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Iynedjian P. B., Möbius G., Seitz H. J., Wollheim C. B., Renold A. E. Tissue-specific expression of glucokinase: identification of the gene product in liver and pancreatic islets. Proc Natl Acad Sci U S A. 1986 Apr;83(7):1998–2001. doi: 10.1073/pnas.83.7.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Iynedjian P. B., Pilot P. R., Nouspikel T., Milburn J. L., Quaade C., Hughes S., Ucla C., Newgard C. B. Differential expression and regulation of the glucokinase gene in liver and islets of Langerhans. Proc Natl Acad Sci U S A. 1989 Oct;86(20):7838–7842. doi: 10.1073/pnas.86.20.7838. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Labarca C., Paigen K. A simple, rapid, and sensitive DNA assay procedure. Anal Biochem. 1980 Mar 1;102(2):344–352. doi: 10.1016/0003-2697(80)90165-7. [DOI] [PubMed] [Google Scholar]
  14. Lachaal M., Jung C. Y. Interaction of facilitative glucose transporter with glucokinase and its modulation by ADP and glucose-6-phosphate. J Cell Physiol. 1993 Aug;156(2):326–332. doi: 10.1002/jcp.1041560215. [DOI] [PubMed] [Google Scholar]
  15. Liang Y., Najafi H., Matschinsky F. M. Glucose regulates glucokinase activity in cultured islets from rat pancreas. J Biol Chem. 1990 Oct 5;265(28):16863–16866. [PubMed] [Google Scholar]
  16. Liang Y., Najafi H., Smith R. M., Zimmerman E. C., Magnuson M. A., Tal M., Matschinsky F. M. Concordant glucose induction of glucokinase, glucose usage, and glucose-stimulated insulin release in pancreatic islets maintained in organ culture. Diabetes. 1992 Jul;41(7):792–806. doi: 10.2337/diab.41.7.792. [DOI] [PubMed] [Google Scholar]
  17. Magnuson M. A. Tissue-specific regulation of glucokinase gene expression. J Cell Biochem. 1992 Feb;48(2):115–121. doi: 10.1002/jcb.240480202. [DOI] [PubMed] [Google Scholar]
  18. Malaisse W. J., Malaisse-Lagae F., Davies D. R., Vandercammen A., Van Schaftingen E. Regulation of glucokinase by a fructose-1-phosphate-sensitive protein in pancreatic islets. Eur J Biochem. 1990 Jul 5;190(3):539–545. doi: 10.1111/j.1432-1033.1990.tb15607.x. [DOI] [PubMed] [Google Scholar]
  19. Matschinsky F. M. Glucokinase as glucose sensor and metabolic signal generator in pancreatic beta-cells and hepatocytes. Diabetes. 1990 Jun;39(6):647–652. doi: 10.2337/diab.39.6.647. [DOI] [PubMed] [Google Scholar]
  20. Matschinsky F., Liang Y., Kesavan P., Wang L., Froguel P., Velho G., Cohen D., Permutt M. A., Tanizawa Y., Jetton T. L. Glucokinase as pancreatic beta cell glucose sensor and diabetes gene. J Clin Invest. 1993 Nov;92(5):2092–2098. doi: 10.1172/JCI116809. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Mondon C. E., Reaven G. M. Evidence of abnormalities of insulin metabolism in rats with spontaneous hypertension. Metabolism. 1988 Apr;37(4):303–305. doi: 10.1016/0026-0495(88)90127-8. [DOI] [PubMed] [Google Scholar]
  22. Permutt M. A., Chiu K. C., Tanizawa Y. Glucokinase and NIDDM. A candidate gene that paid off. Diabetes. 1992 Nov;41(11):1367–1372. doi: 10.2337/diab.41.11.1367. [DOI] [PubMed] [Google Scholar]
  23. Purrello F., Buscema M., Rabuazzo A. M., Caltabiano V., Forte F., Vinci C., Vetri M., Vigneri R. Glucose modulates glucose transporter affinity, glucokinase activity, and secretory response in rat pancreatic beta-cells. Diabetes. 1993 Jan;42(1):199–205. doi: 10.2337/diab.42.1.199. [DOI] [PubMed] [Google Scholar]
  24. SALAS J., SALAS M., VINUELA E., SOLS A. GLUCOKINASE OF RABBIT LIVER. J Biol Chem. 1965 Mar;240:1014–1018. [PubMed] [Google Scholar]
  25. Spears G., Sneyd J. G., Loten E. G. A method for deriving kinetic constants for two enzymes acting on the same substrate. Biochem J. 1971 Dec;125(4):1149–1151. doi: 10.1042/bj1251149. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. van Schaftingen E., Vandercammen A., Detheux M., Davies D. R. The regulatory protein of liver glucokinase. Adv Enzyme Regul. 1992;32:133–148. doi: 10.1016/0065-2571(92)90013-p. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Clinical Investigation are provided here courtesy of American Society for Clinical Investigation

RESOURCES