环磷酸腺苷-鸟嘌呤核苷酸交换因子（Epac）途径参与大鼠腮腺淀粉酶释放的证据。
Evidence for the involvement of cAMP-GEF (Epac) pathway in amylase release from the rat parotid gland.
作者信息
Shimomura Hiromi, Imai Akane, Nashida Tomoko
机构信息
Department of Biochemistry, School of Dentistry at Niigata, The Nippon Dental University, 1-8 Hamaura-cho, Niigata 951-8580, Japan.
出版信息
Arch Biochem Biophys. 2004 Nov 1;431(1):124-8. doi: 10.1016/j.abb.2004.07.021.
Amylase release from the rat parotid gland is mainly mediated in a cAMP-dependent protein kinase (PKA)-dependent manner. In the present study, amylase release mediated in cAMP-dependent and PKA-independent manners was investigated with a cAMP-regulated guanine nucleotide exchange factor (cAMP-GEF: Epac)-selective cAMP analogue, 8CPT-2Me-cAMP. The Epac was localized in the intracellular and the plasma membrane fractions. PKA activation by 8CPT-2Me-cAMP was 100-fold lower than that by cAMP. The amylase release (% of the total) from the intact parotid acinar cells was 16 and 3.6% by isoproterenol (1microM) and 8CPT-2Me-cAMP (200microM), respectively, and that from the saponin-permeabilized cells was 15 and 3% by cAMP (100microM) and 8CTP-2Me-cAMP (10microM), respectively. H-89 inhibited cAMP-induced amylase release, but did not inhibit 8CPT-2Me-cAMP-induced amylase release. These results indicated that amylase release by beta-adrenergic stimulation is mediated through both the cAMP/PKA and cAMP/Epac signal pathways.
大鼠腮腺淀粉酶的释放主要以一种依赖环磷酸腺苷（cAMP）的蛋白激酶（PKA）依赖性方式介导。在本研究中，使用一种cAMP调节的鸟嘌呤核苷酸交换因子（cAMP-GEF：Epac）选择性cAMP类似物8CPT-2Me-cAMP，研究了以cAMP依赖性和PKA非依赖性方式介导的淀粉酶释放。Epac定位于细胞内和质膜部分。8CPT-2Me-cAMP对PKA的激活作用比cAMP低100倍。完整腮腺腺泡细胞中，异丙肾上腺素（1μM）和8CPT-2Me-cAMP（200μM）诱导的淀粉酶释放（占总量的百分比）分别为16%和3.6%，皂苷通透细胞中，cAMP（100μM）和8CTP-2Me-cAMP（10μM）诱导的淀粉酶释放分别为15%和3%。H-89抑制cAMP诱导的淀粉酶释放，但不抑制8CPT-2Me-cAMP诱导的淀粉酶释放这些结果表明，β-肾上腺素能刺激引起的淀粉酶释放是通过cAMP/PKA和cAMP/Epac信号通路介导的。
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