cPLA2alpha-evoked formation of arachidonic acid and lysophospholipids is required for exocytosis in mouse pancreatic beta-cells.
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cPLA2alpha-evoked formation of arachidonic acid and lysophospholipids is required for exocytosis in mouse pancreatic beta-cells. / Juhl, Kirstine; Høy, Marianne; Olsen, Hervør L; Bokvist, Krister; Efanov, Alexander M; Hoffmann, Else K; Gromada, Jesper.
I: American Journal of Physiology: Endocrinology and Metabolism, Bind 285, Nr. 1, 2003, s. E73-81.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - cPLA2alpha-evoked formation of arachidonic acid and lysophospholipids is required for exocytosis in mouse pancreatic beta-cells.
AU - Juhl, Kirstine
AU - Høy, Marianne
AU - Olsen, Hervør L
AU - Bokvist, Krister
AU - Efanov, Alexander M
AU - Hoffmann, Else K
AU - Gromada, Jesper
N1 - Keywords: Animals; Arachidonic Acid; Calcium; Calcium Channels; Chloride Channels; Cytoplasmic Granules; Cytosol; Exocytosis; Female; Group IV Phospholipases A2; Islets of Langerhans; Lipoxygenase Inhibitors; Lysophosphatidylcholines; Lysophospholipids; Membrane Potentials; Mice; Oligonucleotides, Antisense; Patch-Clamp Techniques; Phospholipases A; Phospholipases A2; Stimulation, Chemical
PY - 2003
Y1 - 2003
N2 - 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.
AB - 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.
M3 - Journal article
C2 - 12644445
VL - 285
SP - E73-81
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
SN - 0193-1849
IS - 1
ER -
ID: 6768759