PKA phosphorylation of HERG protein regulates the rate of channel synthesis
PKA phosphorylation of HERG protein regulates the rate of channel synthesis
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DOI：
10.1152/ajpheart.01252.2008
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发表时间：
2009-05-01
影响因子：
4.8
通讯作者：
McDonald, Thomas V.
中科院分区：
文献类型：
--
作者：
Chen, Jian;Sroubek, Jakub;McDonald, Thomas V.
Chen J，Sroubek J，Krishnan Y，Li Y，Bian J，麦当劳电视台。 HERG 蛋白的 PKA 磷酸化调节通道合成速率。 Am J Physiol Heart Circ Physiol 296：H1244-H1254，2009。首次发表于 2009 年 2 月 20 日； doi:10.1152/ajpheart.01252.2008.-cAMP 和蛋白激酶 A (PKA) 信号传导的急性变化可以调节离子通道蛋白活性，例如门控。慢性 PKA 信号传导（如在压力或疾病状态下）对通道的影响尚不清楚。我们在稳定转染的人胚胎肾 (HEK)293 细胞中检查了延长的 PKA 活性对人 ether-a-go-go 相关基因 (HERG) K+ 通道的影响。氯苯硫醇 (CPT)-cAMP 或毛喉素持续升高 cAMP，在 24 小时内使 HERG 通道蛋白丰度增加两到四倍，早在 4 小时就可测量到差异。 cAMP 诱导的增强并非由于转录变化，并且与其他心脏 K+ 通道（Kv1.4、Kv1.5、Kir2.1 和 KvLQT1）相比，对 HERG 具有特异性。 PKA 活性对于 HERG 蛋白的作用是必要的，并且不涉及其他 cAMP 信号通路。 HERG 蛋白的直接 PKA 磷酸化是 cAMP 诱导增强的原因。在富含内质网、高尔基体和质膜中检测到 HERG 蛋白丰度增加，而运输速率或模式没有显着变化。还观察到 HERG 通道携带的 K+ 电流密度增加，但有延迟，表明流向表面的流量是限速流量。 HERG 蛋白合成速率的加速是 cAMP/PKA 效应的主要因素，对蛋白稳定性的影响较小。这些结果为一种新机制提供了证据，新生蛋白质的磷酸化决定其合成速率，重置其稳态丰度。
Chen J, Sroubek J, Krishnan Y, Li Y, Bian J, McDonald TV. PKA phosphorylation of HERG protein regulates the rate of channel synthesis. Am J Physiol Heart Circ Physiol 296: H1244-H1254, 2009. First published February 20, 2009; doi:10.1152/ajpheart.01252.2008.-Acute changes in cAMP and protein kinase A (PKA) signaling can regulate ion channel protein activities such as gating. Effects on channels due to chronic PKA signaling, as in stress or disease states, are less understood. We examined the effects of prolonged PKA activity on the human ether-a-go-go-related gene (HERG) K+ channel in stably transfected human embryonic kidney (HEK)293 cells. Sustained elevation of cAMP by either chlorophenylthiol (CPT)-cAMP or forskolin increased the HERG channel protein abundance two- to fourfold within 24 h, with measurable difference as early as 4 h. The cAMP-induced augmentation was not due to changes in transcription and was specific for HERG compared with other cardiac K+ channels (Kv1.4, Kv1.5, Kir2.1, and KvLQT1). PKA activity was necessary for the effect on HERG protein and did not involve other cAMP signaling pathways. Direct PKA phosphorylation of the HERG protein was responsible for the cAMP-induced augmentation. Enhanced abundance of HERG protein was detected in endoplasmic reticulum-enriched, Golgi, and plasma membrane without significant changes in trafficking rates or patterns. An increase in the K+ current density carried by the HERG channel was also observed, but with a delay, suggesting that traffic to the surface is rate-limiting traffic. Acceleration of the HERG protein synthesis rate was the primary factor in the cAMP/PKA effect with lesser effects on protein stability. These results provide evidence for a novel mechanism whereby phosphorylation of a nascent protein dictates its rate of synthesis, resetting its steady-state abundance.