Dohke Yoko, Fujita-Yoshigaki Junko, Sugiya Hiroshi, Furuyama Shunsuke, Hara-Yokoyama Miki
Department of Physiology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Matsudo, Chiba 271-8587, Japan.
Biochem Biophys Res Commun. 2002 Dec 13;299(4):663-8. doi: 10.1016/s0006-291x(02)02713-4.
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.
大鼠腮腺腺泡细胞中β-肾上腺素能受体的激活会导致细胞内cAMP升高，并显著刺激淀粉酶向唾液中的胞吐释放。钙动员受体的激活也会诱导一些胞吐作用。我们研究了磷脂酶D（PLD）在大鼠腮腺腺泡细胞调节性胞吐中的作用。转磷脂酰化分析在大鼠腮腺腺泡细胞裂解物中检测到了GTPγS（一种不可水解的GTP类似物）依赖性PLD活性，这表明PLD由小分子质量GTP结合蛋白激活。PLD抑制剂新霉素抑制了皂素通透细胞中cAMP依赖性胞吐作用。由于PLD反应产物（磷脂酸）转化为磷脂丁醇，1-丁醇破坏了PLD下游的信号传导。1-丁醇抑制了异丙肾上腺素以及钙动员激动剂（乙酰甲胆碱）对胞吐作用的刺激。这些结果表明，PLD对大鼠腮腺腺泡细胞的调节性胞吐很重要。
