[ Contribution de la Calcium-ATPase de la Membrane Plasmique dans la Sécrétion d’Insuline dans les îlots Pancréatiques de Rat ]
Volume 26, Issue 1, August 2016, Pages 268–279
Adama Kamagate1
1 Laboratoire de Physiologie animale, de Pharmacologie et de Phytothérapie, UFR SN, Université Nangui Abrogoua, Côte d'Ivoire
Original language: French
Copyright © 2016 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The increase in intracellular calcium concentration ([Ca2+]i) represents a major event in the process of insulin secretion. The Plasma Membrane Calcium ATPase (PMCAs) are equipped with a series of isoforms that may be tissue specific. It has been suggested that there might be a difference in activity between the isoforms and that some of them could play a fundamental role in the operation of the β cell. The PMCAs are regulated by calmodulin (CaM), the phospholipid acid, protein kinase, protease, and G protein, and by oligomerisation. CaM activates the pump and this activation effect will be limited by alternative splicing at site C that is their binding domain. Acidic phospholipids are stimulators of PMCA. But, alternative splicing at site A could therefore affect the regulation of PMCA isoforms by phospholipids by altering accessibility of phospholipids to their binding domain. In contrast, the PMCAs are inhibited by lanthanum and vanadate ions, by calmodulin antagonists, N-ethylmaleimide and derivatives of fluorescein. However, the experiments conducted showed that the suppression of the oscillations of [Ca2+] i is accompanied by an increase in glucose metabolism and insulin secretion but which continues to oscillate at a lower frequency. This allowed to say that the oscillations of [Ca2 +]i are not directly involved in the process of oscillations of insulin secretion but could intervene in its fine regulation.
Author Keywords: Diabetes, Insulin, Calcium, PMCA, β cell.
Volume 26, Issue 1, August 2016, Pages 268–279
Adama Kamagate1
1 Laboratoire de Physiologie animale, de Pharmacologie et de Phytothérapie, UFR SN, Université Nangui Abrogoua, Côte d'Ivoire
Original language: French
Copyright © 2016 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The increase in intracellular calcium concentration ([Ca2+]i) represents a major event in the process of insulin secretion. The Plasma Membrane Calcium ATPase (PMCAs) are equipped with a series of isoforms that may be tissue specific. It has been suggested that there might be a difference in activity between the isoforms and that some of them could play a fundamental role in the operation of the β cell. The PMCAs are regulated by calmodulin (CaM), the phospholipid acid, protein kinase, protease, and G protein, and by oligomerisation. CaM activates the pump and this activation effect will be limited by alternative splicing at site C that is their binding domain. Acidic phospholipids are stimulators of PMCA. But, alternative splicing at site A could therefore affect the regulation of PMCA isoforms by phospholipids by altering accessibility of phospholipids to their binding domain. In contrast, the PMCAs are inhibited by lanthanum and vanadate ions, by calmodulin antagonists, N-ethylmaleimide and derivatives of fluorescein. However, the experiments conducted showed that the suppression of the oscillations of [Ca2+] i is accompanied by an increase in glucose metabolism and insulin secretion but which continues to oscillate at a lower frequency. This allowed to say that the oscillations of [Ca2 +]i are not directly involved in the process of oscillations of insulin secretion but could intervene in its fine regulation.
Author Keywords: Diabetes, Insulin, Calcium, PMCA, β cell.
Abstract: (french)
L'augmentation de la concentration de calcium intracellulaire ([Ca2+]i) représente un évènement majeur dans le processus de la sécrétion d'insuline. Les Calcium ATPase de la Membrane Plasmique (PMCA) sont équipées d’une série d’isoformes qui peuvent être tissus spécifiques. Il a été suggéré qu’il pourrait exister une différence d’activité entre les isoformes et que certaines d’entre elles pourraient jouer un rôle fondamental dans le fonctionnement de la cellule β. Les PMCAs sont régulées par la calmoduline (CaM), les phospholipides acides, les protéines kinases, les protéases, les protéines G et par oligomérisation. La CaM active la pompe et cet effet activateur va être limité par l’épissage alternatif au site C qui est leur domaine de fixation. Les phospholipides acides sont des stimulateurs de la PMCA. Mais, l'épissage alternatif au site A pourrait donc affecter la régulation des isoformes de la PMCA par les phospholipides en altérant l'accessibilité des phospholipides à leur domaine de fixation. A l’opposé, les PMCAs sont inhibés par les ions lanthane et vanadate, par les antagonistes de la calmoduline, la N-Ethylmaleimide et Les dérivés de la fluorescéine. Cependant, Les expériences menés ont montré que la suppression des oscillations de la [Ca2+]i est accompagnée par une augmentation du métabolisme du glucose et de la sécrétion d’insuline qui continue à osciller mais avec une périodicité plus faible. Cela amène à dire que les oscillations de la [Ca2+]i ne sont pas directement impliquées dans le processus d’oscillations de la sécrétion d’insuline mais pourraient intervenir dans sa régulation fine.
Author Keywords: Diabète, Insuline, Calcium, PMCA, cellule β.
How to Cite this Article
Adama Kamagate, “Contribution of Plasma Membrane Calcium-ATPase on Insulin Secretion in Rat Pancreatic Islets,” International Journal of Innovation and Scientific Research, vol. 26, no. 1, pp. 268–279, August 2016.
