CAMP potentiates ATP-evoked calcium signaling in human parotid acinar cells
CAMP potentiates ATP-evoked calcium signaling in human parotid acinar cells
复制标题
DOI：
10.1074/jbc.m406201200
复制
发表时间：
2004-09-17
影响因子：
4.8
通讯作者：
Yule, DI
中科院分区：
文献类型：
--
作者：
Brown, DA;Bruce, JIE;Yule, DI
在唾液腺泡细胞中，细胞内钙（[Ca 2 +]（i））信号通过激活Ca 2+激活的离子电导在引起液体分泌中起重要作用。Ca 2+和cAMP对液体分泌具有协同作用，使得在副交感神经和交感神经途径两者的激活之后引起峰值分泌。我们最近发现cAMP通过蛋白激酶A（PKA）介导的小鼠腮腺腺泡细胞1，4，5-三磷酸肌醇受体（InsP（3）R）的磷酸化作用对Ca ~（2+）释放产生影响。为了扩展这些发现，在本研究中，研究了人腮腺腺泡细胞中Ca 2+信号传导和cAMP通路之间的串扰。在人腮腺腺泡细胞中，卡巴胆碱刺激诱发[Ca 2 +]（i）增加，PKA激活后初始峰值振幅增强，与小鼠腮腺的报告一致。用ATP刺激也引起[Ca 2 +]（i）的增加。ATP诱发的Ca ~（2+）升高主要依赖于细胞外Ca ~（2+），表明嘌呤能受体P2 X家族参与其中。cAMP的药理学升高导致由ATP刺激引起的峰值[Ca 2 +]（i）变化增加5倍。这种增强的[Ca 2 +]（i）增加不依赖于InsP（3）R或ryanodine受体的细胞内释放，表明对P2 XR的直接作用。逆转录聚合酶链反应和Western blot分析证实人腮腺腺泡细胞中存在P2 X（4）R和P2 X（7）R mRNA和蛋白。在HEK-293细胞中使用全细胞膜片钳技术研究ATP激活的阳离子电流，P2 XR为零背景。在转染P2 X（4）R DNA的HEK-293细胞中，增加cAMP导致ATP激活电流增加4.5倍，但对表达P2 X（7）R的细胞中的电流没有影响。这些数据表明，在人腮腺腺泡细胞中，除了调节Ca 2+释放外，通过P2 X（4）R的Ca 2+内流可能构成了Ca 2+和PKA激活协同效应的另一个位点。
In salivary acinar cells, intracellular calcium ([Ca2+](i)) signaling plays an important role in eliciting fluid secretion through the activation of Ca2+-activated ionic conductances. Ca2+ and cAMP have synergistic effects on fluid secretion such that peak secretion is elicited following activation of both parasympathetic and sympathetic pathways. We have recently demonstrated that cAMP exerts effects on Ca2+ release, through protein kinase A (PKA)-mediated phosphorylation of inositol 1,4,5-trisphosphate receptors (InsP(3)R) in mouse parotid acinar cells. To extend these findings, in the present study cross-talk between Ca2+ signaling and cAMP pathways in human parotid acinar cells was investigated. In human parotid acinar cells, carbachol stimulation evoked increases in the [Ca2+](i) and the initial peak amplitude was enhanced following PKA activation, consistent with reports from mouse parotid. Stimulation with ATP also evoked an increase in [Ca2+](i). The ATP-evoked Ca2+ elevation was largely dependent on extracellular Ca2+, suggesting the involvement of the P2X family of purinergic receptors. Pharmacological elevation of cAMP resulted in a similar to5-fold increase in the peak [Ca2+](i) change evoked by ATP stimulation. This enhanced [Ca2+](i) increase was not dependent on intracellular release from InsP(3)R or ryanodine receptors, suggesting a direct effect on P2XR. Reverse transcription-polymerase chain reaction and Western blot analysis confirmed the presence of P2X(4)R and P2X(7)R mRNA and protein in human parotid acinar cells. ATP-activated cation currents were studied using whole cell patch clamp techniques in HEK-293 cells, a null background for P2XR. Raising cAMP resulted in a similar to4.5-fold enhancement of ATP-activated current in HEK-293 cells transfected with P2X(4)R DNA but had no effects on currents in cells expressing P2X(7)R. These data indicate that in human parotid acinar cells, in addition to modulation of Ca2+ release, Ca2+ influx through P2X(4)R may constitute a further locus for the synergistic effects of Ca2+ and PKA activation.