Role of β-arrestin-mediated desensitization and signaling in the control of angiotensin AT1a receptor-stimulated transcription
Role of β-arrestin-mediated desensitization and signaling in the control of angiotensin AT1a receptor-stimulated transcription
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DOI：
10.1074/jbc.m706892200
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发表时间：
2008-01-25
影响因子：
4.8
通讯作者：
Luttrell, Louis M.
中科院分区：
文献类型：
--
作者：
Lee, Mi-Hye;El-Shewy, Hesham M.;Luttrell, Louis M.
七螺旋 G 蛋白偶联受体采用多种机制来激活 ERK1/2 级联并控制基因转录。先前对血管紧张素 AT1a 受体的研究表明，G(q/11) 激活会导致 ERK1/2 活性快速且短暂地升高，而 β-arrestin 结合通过支架与内化受体相关的 Raf 中心点 MEK 中心点 ERK 复合物来支持持续的 ERK1/2 激活。在本研究中，我们使用选择性 RNA 干扰比较了两种 β-arrestin 异构体在 AT1a 受体脱敏、ERK1/2 激活和转录中的作用。在 HEK293 细胞中，天然 AT1a 受体和 G 蛋白偶联缺陷的 DRY/AAY 突变体在血管紧张素结合后募集 β-arrestin1 和 β-arrestin2 并与受体内化。相比之下，只有 β-arrestin2 通过 AT1a 和 DRY/AAY 受体支持蛋白激酶 C 独立的 ERK1/2 激活。使用聚焦基因表达过滤阵列来筛选内源转录反应，我们发现单独沉默 beta-arrestin1 或 beta-arrestin2 不会改变反应模式，但沉默两者都会导致转录本数量显着增加，而转录本数量会因 AT1a 受体激活而显着上调。尽管 DRY/AAY 受体能够刺激 β-arrestin2 依赖性 ERK1/2 激活，但它未能引发任何可检测到的转录反应。这些结果表明，对 AT1a 受体激活的转录反应主要反映了异源三聚体 G 蛋白的激活。尽管 beta-arrestin1 和 beta-arrestin2 在支持 G 蛋白独立的 ERK1/2 激活方面具有特殊功能，但它们的共同作用是通过促进受体脱敏来抑制转录反应。
Heptahelical G protein-coupled receptors employ several mechanisms to activate the ERK1/2 cascade and control gene transcription. Previous work with the angiotensin AT1a receptor has shown that G(q/11) activation leads to a rapid and transient rise in ERK1/2 activity, whereas beta-arrestin binding supports sustained ERK1/2 activation by scaffolding a Raf center dot MEK center dot ERK complex associated with the internalized receptor. In this study, we compared the role of the two beta-arrestin isoforms in AT1a receptor desensitization, ERK1/2 activation and transcription using selective RNA interference. In HEK293 cells, both the native AT1a receptor and a G protein-coupling deficient DRY/AAY mutant recruited beta-arrestin1 and beta-arrestin2 upon angiotensin binding and internalized with the receptor. In contrast, only beta-arrestin2 supported protein kinase C-independent ERK1/2 activation by both the AT1a and DRY/AAY receptors. Using focused gene expression filter arrays to screen for endogenous transcriptional responses, we found that silencing beta-arrestin1 or beta-arrestin2 individually did not alter the response pattern but that silencing both caused a marked increase in the number of transcripts that were significantly up-regulated in response to AT1a receptor activation. The DRY/AAY receptor failed to elicit any detectable transcriptional response despite its ability to stimulate beta-arrestin2- dependent ERK1/2 activation. These results indicate that the transcriptional response to AT1a receptor activation primarily reflects heterotrimeric G protein activation. Although beta-arrestin1 and beta-arrestin2 are functionally specialized with respect to supporting G protein-independent ERK1/2 activation, their common effect is to dampen the transcriptional response by promoting receptor desensitization.