Rapid Turnover of Phosphatidylinositol-4,5-Bisphosphate in Insulin-Secreting Cells Mediated by Ca2+ and the ATP-to-ADP Ratio
| Autor: | Anne Wuttke, Anders Tengholm, Sophia Thore |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Phosphatidylinositol 4
5-Diphosphate musculoskeletal diseases Endocrinology Diabetes and Metabolism Adenylate kinase Cell Line Mice chemistry.chemical_compound Adenosine Triphosphate Adenine nucleotide Insulin-Secreting Cells Internal Medicine Animals Phospholipase C Chemistry Hydrolysis Cell Membrane Adenosine Diphosphate Pleckstrin homology domain Adenosine diphosphate Glucose Biochemistry Phosphatidylinositol 4 5-bisphosphate Second messenger system Biophysics Calcium lipids (amino acids peptides and proteins) Adenosine triphosphate |
| Zdroj: | Diabetes. 56:818-826 |
| ISSN: | 1939-327X 0012-1797 |
| DOI: | 10.2337/db06-0843 |
| Popis: | Phosphatidylinositol-4,5-bisphosphate (PIP(2)) is important for a variety of cellular processes as a precursor for second messengers and by regulating ion channels, the cytoskeleton, and vesicle traffic in many types of cells, including insulin-secreting beta-cells. Here, we applied evanescent wave microscopy and the PIP(2)-binding pleckstrin homology domain from phospholipase C (PLC)-delta fused to the green fluorescent protein to characterize the regulation of plasma membrane PIP(2) in individual insulin-secreting MIN6 beta-cells. Elevation of the glucose concentration from 3 to 11 mmol/l evoked antisynchronous oscillations of [PIP(2)] and cytoplasmic Ca(2+)concentration, consistent with PLC being periodically activated by the voltage-dependent Ca(2+) influx. The effect of adenine nucleotides on [PIP(2)] was studied in cells permeabilized with alpha-toxin. ATP dose- dependently stimulated PIP(2) synthesis with half-maximal effect at 300 mumol/l. Omission of the nucleotide resulted in rapid loss of PIP(2) with t(1/2) < 40 s. ADP also stimulated PIP(2) formation, but this effect reflected local ATP formation and was prevented by the adenylate kinase inhibitor diadenosine-pentaphosphate. The ATP-induced PIP(2) synthesis was counteracted by the ADP analog adenosine-5'-O-2-thiodiphosphate. We conclude that plasma membrane PIP(2) is dynamically regulated by intracellular Ca(2+) and the ATP-to-ADP ratio in insulin-secreting cells. The rapid turnover allows maintenance of PIP(2) levels while generating second messengers of critical importance for insulin secretion. |
| Databáze: | OpenAIRE |
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