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GTP and Its Binding Proteins in the Regulation of Insulin Exocytosis

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Molecular Biology of Diabetes

Abstract

Despite considerable evidence for the involvement of the purine nucleotides GTP* and ATP in exocytosis, there is currently no consensus about their exact role(s). With regard to GTP (the focus of this chapter), our recent studies (1) have suggested that there is at least a permissive role for GTP in insulin release. Normal rat pancreatic islets were pretreated overnight with each of four structurally-dissimilar inhibitors of a rate-limiting step in the cytosolic production of GTP (inosine monophosphate dehydrogenase; IMPDH). When islet concentrations of GTP were inhibited by more than about 80% (to levels down to less than 0.6–0.7 pmol/islet), insulin release subsequently stimulated by nutrients (glucose or α-ketoisocaproate) or by aphorbol ester was reduced 40–60%. In contrast, insulin secretion induced by direct depolarization of β-cells (by 50 m M K+) was refractory to inhibition. These results were attributed to a depletion of islet GTP stores, since repletion of GTP by coprovision of guanine (but not the normalization of both ATP and UTP content by the provision of adenine) reversed the inhibitory effects of the drugs both on GTP content and on insulin release. In subsequent studies, we observed that lesser degrees of inhibition of GTP, or, conversely, a stimulation of islet GTP content (by provision of guanine alone) to levels about 25% above basal, did not have any discernible negative or positive modulatory effects on secretion. These findings suggested that islet GTP content is normally saturating, and therefore mild to moderate changes in these levels do not alter secretion. Since the average islet content of GTP approximates 750–1000 μM, it appears that a reduction in total islet GTP levels to less than 150–200 μM (or, possibly, a comparable relative reduction of free GTP levels, which may be one-fifth to one-twentieth of total levels; ref. 2) is needed to vitiate the effects of GTP on secretion. Such drastic changes are not likely to be induced by physiologic agonists (and in fact were not induced by glucose, which had relatively modest effects on total islet GTP content); therefore, we defined the effects of GTP as “permissive.”

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References

  1. Metz SA, Rabaglia ME, Pintar TJ: Selective inhibitors of GTP synthesis impede exocytotic insulin release from intact rat islets. J Biol Chem 267:12, 517-12, 527, 1992.

    Google Scholar 

  2. Otero A de S: Transphosphorylation and G protein activation. Biochem Pharmacol 39:1399–1404, 1990.

    Article  Google Scholar 

  3. Haun RS, Tsai S-C, Adamik R, Moss J, Vaughan M: Effect of myristoylation on GTP-dependent binding of ADP-ribosylation factor to Golgi. J Biol Chem 268:7064–7068, 1993.

    Google Scholar 

  4. Lillie THW, Gomperts BD: Guanine nucleotide is essential and Ca2+ is a modulator in the exocytotic reaction of permeabilized rat mast cells. Biochem J 288:181–187, 1992.

    Google Scholar 

  5. Lillie THW, Gomperts BD: Kinetic characterization of guanine-nucleotide-induced exocytosis from permeabilized rat mast cells. Biochem J 290:389–394, 1993.

    Google Scholar 

  6. Ahnert-Hilger G, Dayanithi G, Spicher K, Nordmann JJ: G-proteins mediate inhibition and activation of Ca2+-induced exocytosis from SLO-permeabilized peptidergic nerve endings. Biosci Rep 12:463–469, 1992.

    Article  Google Scholar 

  7. Metz SA, Meredith M, Kowluru A: Purine nucleotide metabolism and GTP-binding proteins in the pancreatic β-cell. In Frontiers of Pancreatic β-Cell Research (Flatt PR, ed.), 1994, in press.

    Google Scholar 

  8. Metz SA, Meredith M, Rabaglia ME, Kowluru A: Small elevations of glucose concentration re-direct and amplify the synthesis of GTP in rat islets. J Clin Invest 92:872–882, 1993.

    Article  Google Scholar 

  9. Welsh N, Sandier S, Welsh M, Hellerströ M: Regulation of RNA metabolism in relation to insulin production and oxidative metabolism in mouse pancreatic islets in vitro. Biochim Biophys Acta 887:58–68, 1986.

    Article  Google Scholar 

  10. Liang Y, Najafi H, Smith RM, Zimmerman EC, Magnuson MA, Tal M, Matschinsky FM: Concordant glucose induction of glucokinase, glucose usage, and glucose-stimulated insulin release in pancreatic islets maintained in organ culture. Diabetes 41:792–806, 1992.

    Article  Google Scholar 

  11. Metz SA: Epinephrine impairs insulin release by a mechanism distal to calcium mobilization. Similarity to lipoxygenase inhibitors. Diabetes 37:65–73, 1988.

    Article  Google Scholar 

  12. Gembal M, Detimary P, Gilon P, Gao Z-Y, Henquin J-C: Mechanisms by which glucose can control insulin release independently from its action on adenosine triphosphate-sensitive K+ channels in mouse B cells. J Clin Invest 91:871–880, 1993.

    Article  Google Scholar 

  13. Ullrich, S, Prentki, M, Wollheim, CB: Somatostatin inhibition of Ca2+-induced insulin secretion in permeabilized HIT-T15 cells. Biochem J 270:273–276, 1990.

    Google Scholar 

  14. Koffer A: Calcuim-induced secretion from permeabilized rat mast cells: requirements for guanine nucleotides. Biochim Biophys Acta 1176:231–239, 1993.

    Article  Google Scholar 

  15. Lauquin GJM, Villiers C, Michejda JW, Hryniewiecka LV, Vignais PV: Adenine nucleotide transport in sonic submitochondrial particles. Kinetic properties and binding of specific inhibitors. Biochim Biophys Acta 460:331–345, 1977.

    Article  Google Scholar 

  16. MacDonald MJ, Fahien LA: Glyceraldehyde phosphate and methyl esters of succinic acid. Two “new” potent insulin secretagogues. Diabetes 37:997–999, 1988.

    Article  Google Scholar 

  17. Fahien LA, MacDonald MJ, Kmiotek EH, Mertz RJ, Fahien CM: Regulation of insulin release by factors that also modify glutamine dehydrogenase. J Biol Chem 263:13, 610-13, 614, 1988.

    Google Scholar 

  18. Miyake R, Gross RW: Multiple phospholipase A2 activities in canine vascular smooth muscle. Biochim Biophys Acta 1165:167–176, 1992.

    Article  Google Scholar 

  19. Davfetov B, Marie-Sontag J-M, Hata Y, Petrenko AG, Fykse EM, Jahn R, Sudhof TC: Phosphorylation of synaptotagmin I by casein kinase II. J Biol Chem 268:6816–6822, 1993.

    Google Scholar 

  20. Cordella-Miele E, Miele L, Beninati S, Mukherjee AB: Transglutaminase-catalyzed incorporation of polyamines into phospholipase A2. J Biochem (Tokyo) 113:164–173, 19

    Google Scholar 

  21. Facchiano F, Benfenati F, Valtorta F, Luini A: Covalent modification of synapsin I by a tetanus toxin-activated transglutaminase. J Biol Chem 268:4588–4591, 1993.

    Google Scholar 

  22. Zünkler B J, Lenzen S, Panten U: D-glucose enhances GTP content in mouse pancreatic islets. IRCS Med Sci 14:354, 355, 1986.

    Google Scholar 

  23. Robertson RP, Seaquist ER, Walseth TF: G proteins and modulation of insulin secretion. Diabetes 40:1–6, 1991.

    Article  Google Scholar 

  24. Helper JR, Gilman AG: G-proteins. TIBS 17:383–387, 1992.

    Google Scholar 

  25. Katada T, Ui M: Islet activating protein. Enhanced secretion and cyclic AMP accumulation in pancreatic islets due to activation of native calcium ionophores. J Biol Chem 254:469–479, 1979.

    Google Scholar 

  26. Nakakki G, Nakadate T, Ishili K, Kato R: Postsynaptic alpha 2 adrenergic receptors in isolated rat islets of Langerhans: Inhibition of insulin release and cyclic 3′ 5′ adenosine monophosphate accumulation. J Pharmacol Exp Ther 216:607–614, 1981.

    Google Scholar 

  27. Hillaire-Buys D, Gross R, Roye M, Ribes G, Loubatieres-Mariani M-M: Adrenergic inhibition of insulin secretion involves pertussis toxin-sensitive and-insensitive mechanisms. Eur J Pharmacol 218:3359–3362, 1992.

    Article  Google Scholar 

  28. Morgan NG, Berrows NS: Immunological characterization of pertussis toxin-sensitive G-proteins in isolated islets and cultured insulinoma cells. Diabetologia 35(supp 1):A118, 1992.

    Google Scholar 

  29. Kowluru A, Rabaglia ME, Muse KE, Metz SA: Subcellular localization and kinetic characterization of guanine nucleotide binding proteins in normal rat and human pancreatic islets and transformed beta cells. Biochim Biophys Acta 1994, in press.

    Google Scholar 

  30. Takai Y, Kaibuchi K, Kikuchi A, Kawata M: Small GTP-binding proteins. Int Rev Cytol 133:187–230, 1992.

    Article  Google Scholar 

  31. Kowluru A, Metz SA: Stimulation by prostaglandin E2 of a high affinity GTPase in the secretory granules of normal rat and human pancreatic islets. Biochem J 297:399–406, 1994.

    Google Scholar 

  32. Kowluru A, Metz SA: Regulation of guanine-nucleotide binding proteins in islet subcellular fractions by phospholipase-derived lipid mediators of insulin secretion. Biochim Biophys Acta 1994, in press.

    Google Scholar 

  33. Regazzi R, Vallar L, Ullrich S, Ravazzola M, Kikuchi A, Takai Y, Wollheim CB: Characterization of small-molecular-mass guanine nucleotide-binding regulatory proteins in insulin-secreting cells and PC 12 cells. Eur J Biochem 208:729–737, 1992

    Google Scholar 

  34. Bourne HR, Sanders DA, McCormick F: The GTPase superfamily: a conserved switch for diverse cell functions. Nature 348:125–132, 1990.

    Article  Google Scholar 

  35. Boyer JL, Waldo GL, Harden TK: βy-subunit activation of G-protein-regulated phospholipase C.J Biol Chem 267:25, 451-25, 456, 1992.

    Google Scholar 

  36. Katz A, Wu D, Simon MI: Subunits βγ of heterotrimeric G protein activate β2 isoform of phospholipase. Nature 360:686–689, 1992.

    Article  Google Scholar 

  37. Creutz CE: The annexins and exocytosis. Science 258:924–931, 1992.

    Article  Google Scholar 

  38. Zupan LA, Steffans DL, Erry CA, Landt M, Gross RW: Cloning and expression of a human 14-3-3 protein mediating phospholipolysis. J Biol Chem 267:8707–8710, 1992.

    Google Scholar 

  39. Dunlop ME, Larkins RG: Effect of phosphatidic acid on islet cell phosphoinositidehydrolysis, Ca2+,andadenylatecyclase.Diabetes38:1187–1192,1989.

    Article  Google Scholar 

  40. Metz SA, Rabaglia ME, Stock J, Kowluru A: Modulation of insulin secretion from normal rat islets by inhibitors of the posttranslational modifications of GTP-binding proteins. Biochem J, 295:31–40, 1993.

    Google Scholar 

  41. Kowluru A, Rabaglia ME, Stock J, Metz SA: A requirement in exocytotic insulin secretion for GTP-dependent carboxyl methylation of specific islet proteins. Diabetes 42:76A, 1993.

    Google Scholar 

  42. Metz SA: Ether-linked lysophospholipids initiate insulin secretion. Lysophospholipids may mediate effects of phospholipase A2 activation on hormone release. Diabetes 35:808–817, 1986.

    Article  Google Scholar 

  43. Metz SA: Exogenous arachidonic acid promotes insulin release from intact or permeabilized rat islets by dual mechanisms. Diabetes 37:1453–1469, 1988.

    Article  Google Scholar 

  44. Metz SA, Draznin B, Sussman KE, Leitner JW: Unmasking of arachidonate-induced insulin release by removal of extracellular calcium. Biochem Biophys Res Commun 142:251–258, 1987.

    Article  Google Scholar 

  45. Seaquist ER, Walseth TF, Nelson DM, Robertson RP: Pertussis toxin-sensitive G-protein mediation of PGE2 inhibition of cAMP metabolism and phasic glucose-induced insulin secretion in HIT cells. Diabetes 38:1439–1445, 1989.

    Article  Google Scholar 

  46. Sharp GWG, Merchand-Brustel YL, Yada T, Russo LL, Bliss CR, Cormont M, Monge L, Van Obberghen E: Galanin can inhibit insulin release by a mechanism other than membrane hyperpolarization or inhibition of adenylate cyclase. J Biol Chem 264:7302–7309, 1989.

    Google Scholar 

  47. Persaud SJ, Jones PM, Howell SL: Effects of Bordetella pertussis toxin on catecholamine inhibition of insulin release from intact and electrically permeabilized rat islets. Biochem J 258:669–675, 1989.

    Google Scholar 

  48. Basudev H, Jones PM, Persaud SJ, Howell SL: Arachidonic acid-induced insulin secretion from rat islets of Langerhans is not mediated by protein phosphorylation. Mol Cell Endocrinol 91:193–199, 1993.

    Article  Google Scholar 

  49. Vara E, Tamarit-Rodriguez J: Glucose stimulation of insulin secretion in islets of fed and starved rats and its dependence of lipid metabolism. Metabolism 35:266–271, 1986.

    Article  Google Scholar 

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Authors
  1. Anjaneyulu Kowluru
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  2. Stewart A. Metz
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Editor information

Editors and Affiliations

  1. University of Colorado Health Sciences Center, Denver, CO, USA

    Boris Draznin MD, PhD

  2. National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA

    Derek LeRoith MD, PhD

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© 1994 Springer Science+Business Media New York

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Kowluru, A., Metz, S.A. (1994). GTP and Its Binding Proteins in the Regulation of Insulin Exocytosis. In: Draznin, B., LeRoith, D. (eds) Molecular Biology of Diabetes. Humana Press, Totowa, NJ. https://doi.org/10.1007/978-1-4612-0241-7_11

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  • DOI: https://doi.org/10.1007/978-1-4612-0241-7_11

  • Publisher Name: Humana Press, Totowa, NJ

  • Print ISBN: 978-1-4612-6677-8

  • Online ISBN: 978-1-4612-0241-7

  • eBook Packages: Springer Book Archive

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