Stable interaction between β-arrestin 2 and angiotensin type 1A receptor is required for β-arrestin 2-mediated activation of extracellular signal-regulated kinases 1 and 2
Stable interaction between β-arrestin 2 and angiotensin type 1A receptor is required for β-arrestin 2-mediated activation of extracellular signal-regulated kinases 1 and 2
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DOI：
10.1074/jbc.m406205200
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发表时间：
2004-11-12
影响因子：
4.8
通讯作者：
Lefkowitz, RJ
中科院分区：
文献类型：
--
作者：
Wei, HJ;Ahn, S;Lefkowitz, RJ
受体（7 MSRs）不仅导致受体脱敏和内吞作用，而且还引发额外的信号传导过程。我们最近提出，刺激血管紧张素1A型（AT（1A））受体导致独立的β-抑制蛋白2和G蛋白介导的细胞外信号调节激酶1和2（ERK 1/2）激活。在这里，我们利用两个AT（1A）突变受体来研究这些独立的途径，一个在残基324处截短，从而去除所有潜在的羧基末端磷酸化位点，另一个在羧基末端富含丝氨酸/苏氨酸的簇中具有四个突变。通过共聚焦显微镜评估，两种突变受体与β-抑制蛋白2-绿色荧光蛋白相互作用的亲和力比野生型受体低得多。此外，突变受体更有力地刺激G蛋白介导的磷酸肌醇的产生。大约一半的野生型AT（1A）受体刺激的ERK 1/2激活是通过β-arrestin 2依赖性途径（被β-arrestin 2小干扰RNA抑制），而其余的是由G蛋白依赖性途径介导的（被蛋白激酶C抑制剂抑制）。突变型受体对ERK 1/2的激活对β-arrestin 2小干扰RNA不敏感，但蛋白激酶C抑制剂可使ERK 1/2的激活降低80%以上。G蛋白和β-arrestin 2依赖性途径激活ERK的生化后果也不同。G蛋白介导的ERK激活增强了早期生长反应1的转录，而β-arrestin 2依赖的ERK激活没有。此外，截短的AT（1A）突变体受体的刺激引起显着更大的早期生长反应1转录比野生型受体。这些发现表明受体与β-arrestins相互作用的能力如何决定ERK激活的机制以及这种激活的生理后果。
receptors (7MSRs) not only leads to receptor desensitization and endocytosis but also elicits additional signaling processes. We recently proposed that stimulation of the angiotensin type 1A (AT(1A)) receptor results in independent beta-arrestin 2- and G protein-mediated extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation. Here we utilize two AT(1A) mutant receptors to study these independent pathways, one truncated at residue 324, thus removing all potential carboxyl-terminal phosphorylation sites, and the other bearing four mutations in the serine/threonine-rich clusters in the carboxyl terminus. As assessed by confocal microscopy, the two mutant receptors interacted with beta-arrestin 2- green fluorescent protein with much lower affinity than did the wild-type receptor. In addition, the mutant receptors more robustly stimulated G protein-mediated inositol phosphate production. Approximately one-half of the wild-type AT(1A) receptor-stimulated ERK1/2 activation was via a beta-arrestin 2-dependent pathway ( suppressed by beta-arrestin 2 small interfering RNA), whereas the rest was mediated by a G protein-dependent pathway ( suppressed by protein kinase C inhibitor). ERK1/2 activation by the mutant receptors was insensitive to beta-arrestin 2 small interfering RNA but was reduced more than 80% by a protein kinase C inhibitor. The biochemical consequences of ERK activation by the G protein and beta-arrestin 2-dependent pathways were also distinct. G-protein-mediated ERK activation enhanced the transcription of early growth response 1, whereas beta-arrestin 2- dependent ERK activation did not. In addition, stimulation of the truncated AT(1A) mutant receptor caused significantly greater early growth response 1 transcription than did the wild-type receptor. These findings demonstrate how the ability of receptors to interact with beta-arrestins determines both the mechanism of ERK activation as well as the physiological consequences of this activation.