cAMP oscillations restrict protein kinase A redistribution in insulin-secreting cells
cAMP oscillations restrict protein kinase A redistribution in insulin-secreting cells
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DOI：
10.1042/bst0340498
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发表时间：
2006-08-01
影响因子：
3.9
通讯作者：
Tengholm, A.
中科院分区：
文献类型：
--
作者：
Dyachok, O.;Sagetorp, J.;Tengholm, A.
最近发现激素受体的激活会引起胰岛素分泌细胞质膜下的 cAMP 浓度 ([cAMP]) 振荡。在这里，我们研究 cAMP 信号的不同时间进程如何影响单个 INS-1 β 细胞中细胞质 Ca2+ 信号的产生和 PKA（蛋白激酶 A）催化亚基的核转位。 [cAMP] 使用荧光易位生物传感器和比例倏逝波显微镜进行测量。使用落射荧光显微镜和四半胱氨酸标记的 PKA-C α 亚基的 FlASH（荧光素砷螺旋结合剂）标记对 PKA 核易位进行分析。用异丁基甲基黄嘌呤间歇性或持续抑制磷酸二酯酶诱导的 [cAMP] 振荡和稳定升高都会引起 Ca2+ 尖峰。在 [cAMP] 振荡期间，Ca2+ 尖峰仅限于 [cAMP] 升高的时期。相反，只有稳定的[cAMP]升高才能诱导FlAsH标记的PKA-Cα进入核。这些结果表明，[cAMP] 的振荡通过限制 PKA 的空间重新分布导致选择性靶标激活。
Activation of hormone receptors was recently found to evoke oscillations of the cAMP concentration ([cAMP]) beneath the plasma membrane of insulin-secreting cells. Here we investigate how different time courses of cAMP signals influence the generation of cytoplasmic Ca2+ signals and nuclear translocation of the PKA (protein kinase A) catalytic subunit in individual INS-1 beta-cells. [cAMP] was measured with a fluorescent translocation biosensor and ratiometric evanescent wave microscopy. Analysis of PKA nuclear translocation was performed with epifluorescence microscopy and FlASH (fluorescein arsenical helix binder) labelling of tetracysteine-tagged PKA-C alpha subunit. Both oscillatory and stable elevations of [cAMP] induced by intermittent or constant inhibition of phosphodiesterases with isobutylmethylxanthine evoked Ca2+ spiking. During [cAMP] oscillations, the Ca2+ spiking was restricted to the periods of elevated [cAMP]. In contrast, only stable [cAMP] elevation induced nuclear entry of FlAsH-labelled PKA-C alpha. These results indicate that oscillations of [cAMP] lead to selective target activation by restricting the spatial redistribution of PKA.