The effects of acute and chronic nadolol treatment on β2AR signaling in HEK293 cells.
The effects of acute and chronic nadolol treatment on β2AR signaling in HEK293 cells.
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急性和慢性纳多洛尔治疗对HEK293 细胞β2AR 信号传导的影响。
DOI：
10.1007/s00210-010-0591-9
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Knoll,BrianJ
中科院分区：
文献类型：
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作者：
Peng,Hui;Bond,RichardA;Knoll,BrianJ
纳多洛尔（NAD）是一种β-肾上腺素能受体阻滞剂，对β AR具有反向激动剂活性。我们实验室的先前研究表明，在哮喘的鼠模型中，用NAD的慢性治疗降低了对毒蕈碱激动剂乙酰甲胆碱的气道阻力反应（Raw），而用NAD的急性治疗增加了Raw（Callaerts-Vegh等人，Proc Natl Acad Sci U S A 101：4948 - 4953，2004）。在鼠哮喘模型中，用NAD长期治疗也引起气道炎症和粘蛋白含量降低（Nguyen et al.，Am J Respir Cell Mol Biol 38：256 - 262，2008）。在这项研究中，我们使用表达人β 2AR的HEK 293细胞系，检测了纳多洛尔对β 2AR水平和β 2AR下游信号组分的影响。用NAD长期处理增加β 2AR蛋白水平并减少受体降解，与反向激动剂的受体稳定性一致。基础cAMP水平下降后5分钟的治疗与NAD，但增加后24小时的治疗。NAD处理5 min可降低毛喉素刺激的β 2AR PKA位点Ser 262的磷酸化，而NAD处理24 h可增加毛喉素刺激的β 2AR PKA位点Ser 262的磷酸化。相反，NAD长期处理对β 2AR GRK位点Ser 355、356的磷酸化没有影响。NAD慢性处理上调G α s的细胞水平，但对G α i无影响。因此，慢性NAD治疗通过包括β 2AR和G α s上调的机制增加细胞cAMP水平。这种作用可以部分解释慢性纳多洛尔治疗对气道收缩性的有益作用。
Nadolol (NAD) is a β-adrenergic receptor blocker with inverse agonist activity at βARs. Previous studies in our laboratory showed that chronic treatment with NAD decreased airway resistance response (Raw) to the muscarinic agonist methacholine in a murine model of asthma while acute treatment with NAD increasedRaw(Callaerts-Vegh et al., Proc Natl Acad Sci U S A 101:4948–4953, 2004). Chronic treatment with NAD also caused decreased airway inflammation and mucin content in a murine asthma model (Nguyen et al., Am J Respir Cell Mol Biol 38:256–262, 2008). In this study, we examined the effects of nadolol on β2AR levels and signaling components downstream of the β2AR using a line of HEK293 cells expressing human β2ARs. Chronic treatment with NAD increased β2AR protein levels and decreased receptor degradation,consistent with receptor stabilization by the inverse agonist. Basal cAMP levels decreased after 5 min of treatment with NAD but increased after a 24-h treatment. A 5-min treatment with NAD decreased forskolin-stimulated phosphorylation at the β2AR PKA site Ser 262 while a 24-h treatment with NAD increased it. In contrast,chronic treatment with NAD had no effect on phosphorylation of the β2AR GRK site at Ser 355, 356. Chronic treatment with NAD upregulated cellular levels of Gαs but had no effect on Gαi. Chronic NAD treatment therefore increases cellular cAMP levels by mechanisms that include the upregulation of β2AR and Gαs. This effect may explain in part the beneficial effects of chronic nadolol treatment on airway contractility.