Involvement of phospholipase D in the cAMP-regulated exocytosis of rat parotid acinar cells.
The activation of beta-adrenergic receptors in rat parotid acinar cells causes intracellular cAMP elevation and appreciably stimulates the exocytotic release of amylase into saliva. The activation of Ca(2+)-mobilizing receptors also induces some exocytosis. We investigated the role of phospholipase D (PLD) in regulated exocytosis in rat parotid acinar cells. A transphosphatidylation assay detected GTPgammaS (a nonhydrolyzable analogue of GTP)-dependent PLD activity in lysates of rat parotid acinar cells, suggesting that PLD is activated by small molecular mass GTP-binding proteins. The PLD inhibitor, neomycin, suppressed cAMP-dependent exocytosis in saponin-permeabilized cells. Signaling downstream of PLD was disrupted by 1-butanol due to conversion of the PLD reaction product (phosphatidic acid) to phosphatidylbutanol. The stimulation of exocytosis by isoproterenol as well as by a Ca(2+)-mobilizing agonist (methacholine) was inhibited by 1-butanol. These results suggest that PLD is important for regulated exocytosis in rat parotid acinar cells.
Dohke
Yoko
Y
Department of Physiology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Matsudo, Chiba 271-8587, Japan.
Fujita-Yoshigaki
Junko
J
Sugiya
Hiroshi
H
Furuyama
Shunsuke
S
Hara-Yokoyama
Miki
M
D000681:Amylases / Q000378:metabolism; D000818:Animals; D000440:Butanols / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D009355:Neomycin / Q000494:pharmacology; D010277:Parasympathomimetics / Q000494:pharmacology; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D013566:Sympathomimetics / Q000494:pharmacology
D000440:Butanols; D010277:Parasympathomimetics; D011500:Protein Synthesis Inhibitors; D013566:Sympathomimetics; D016210:Methacholine Chloride; D000242:Cyclic AMP; D010739:Phospholipase D; D000681:Amylases; D009355:Neomycin; D007545:Isoproterenol; D002118:Calcium