Rapid turnover of phosphatidylinositol-4,5-bisphosphate in insulin-secreting cells mediated by Ca2+ and the ATP-to-ADP ratio
2007 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 56, no 3, 818-826 p.Article in journal (Refereed) Published
Phosphatidylinositol-4,5-bisphosphate (PIP2) 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 β-cells. Here, we applied evanescent wave microscopy and the PIP2-binding pleckstrin homology domain from phospholipase C (PLC)-δ fused to the green fluorescent protein to characterize the regulation of plasma membrane PIP2 in individual insulin-secreting MIN6 β-cells. Elevation of the glucose concentration from 3 to 11 mmol/l evoked antisynchronous oscillations of [PIP2] and cytoplasmic Ca2+concentration, consistent with PLC being periodically activated by the voltage-dependent Ca2+ influx. The effect of adenine nucleotides on [PIP2] was studied in cells permeabilized with α-toxin. ATP dose- dependently stimulated PIP2 synthesis with half-maximal effect at 300 μmol/l. Omission of the nucleotide resulted in rapid loss of PIP2 with t1/2 < 40 s. ADP also stimulated PIP2 formation, but this effect reflected local ATP formation and was prevented by the adenylate kinase inhibitor diadenosine-pentaphosphate. The ATP-induced PIP2 synthesis was counteracted by the ADP analog adenosine-5′-O-2-thiodiphosphate. We conclude that plasma membrane PIP2 is dynamically regulated by intracellular Ca2+ and the ATP-to-ADP ratio in insulin-secreting cells. The rapid turnover allows maintenance of PIP2 levels while generating second messengers of critical importance for insulin secretion.
Place, publisher, year, edition, pages
2007. Vol. 56, no 3, 818-826 p.
Adenosine Diphosphate/*metabolism, Adenosine Triphosphate/*metabolism, Animals, Calcium/*metabolism, Cell Line, Cell Membrane/metabolism, Glucose, Hydrolysis, Insulin-Secreting Cells/*metabolism, Mice, Phosphatidylinositol 4;5-Diphosphate/*metabolism
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-12845DOI: 10.2337/db06-0843ISI: 000244827500032PubMedID: 17327453OAI: oai:DiVA.org:uu-12845DiVA: diva2:40614