| Autor: |
Juhl K; Laboratory of Islet Cell Physiology, Novo Nordisk, Bagsvaerd, Denmark., Høy M, Olsen HL, Bokvist K, Efanov AM, Hoffmann EK, Gromada J |
| Jazyk: |
angličtina |
| Zdroj: |
American journal of physiology. Endocrinology and metabolism [Am J Physiol Endocrinol Metab] 2003 Jul; Vol. 285 (1), pp. E73-81. Date of Electronic Publication: 2003 Mar 18. |
| DOI: |
10.1152/ajpendo.00086.2003 |
| Abstrakt: |
Using capacitance measurements, we investigated the effects of intracellularly applied recombinant human cytosolic phospholipase A2 (cPLA2alpha) and its lipolytic products arachidonic acid and lysophosphatidylcholine on Ca2+-dependent exocytosis in single mouse pancreatic beta-cells. cPLA2alpha dose dependently (EC50 = 86 nM) stimulated depolarization-evoked exocytosis by 450% without affecting the whole cell Ca2+ current or cytoplasmic Ca2+ levels. The stimulatory effect involved priming of secretory granules as reflected by an increase in the size of the readily releasable pool of granules from 70-80 to 280-300. cPLA2alpha-stimulated exocytosis was antagonized by the specific cPLA2 inhibitor AACOCF3. Ca2+-evoked exocytosis was reduced by 40% in cells treated with AACOCF3 or an antisense oligonucleotide against cPLA2alpha. The action of cPLA2alpha was mimicked by a combination of arachidonic acid and lysophosphatidylcholine (470% stimulation) in which each compound alone doubled the exocytotic response. Priming of insulin-containing secretory granules has been reported to involve Cl- uptake through ClC-3 Cl- channels. Accordingly, the stimulatory action of cPLA2alpha was inhibited by the Cl- channel inhibitor DIDS and in cells pretreated with ClC-3 Cl- channel antisense oligonucleotides. We propose that cPLA2alpha has an important role in controlling the rate of exocytosis in beta-cells. This effect of cPLA2alpha reflects an enhanced transgranular Cl- flux, leading to an increase in the number of granules available for release, and requires the combined actions of arachidonic acid and lysophosphatidylcholine. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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