Gβ2 and Gβ4 participate in the opioid and adrenergic receptor-mediated Ca2+ channel modulation in rat sympathetic neurons.
Gβ2 and Gβ4 participate in the opioid and adrenergic receptor-mediated Ca2+ channel modulation in rat sympathetic neurons.
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Gβ2 和Gβ4 参与大鼠交感神经元中阿片类药物和肾上腺素受体介导的Ca2 通道调节。
DOI：
10.1113/jphysiol.2012.237644
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Ruiz-Velasco,Victor
中科院分区：
文献类型：
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作者：
Mahmoud,Saifeldin;Yun,JongK;Ruiz-Velasco,Victor
关键点·支配心肌的交感星状神经节（SG）神经元在调节心率和收缩性方面发挥重要作用。·在这项研究中，我们研究了哪种Gβ蛋白亚基将Ca 2+通道与SG神经元中表达的阿片受体和肾上腺素能受体偶联。我们发现Gβ2和Gβ4是维持两种受体亚型和Ca 2+通道的转导途径的重要信号传导元件，以及它们的表达水平是如何差异补偿的。我们的研究结果还表明，Gβ1亚基似乎在两种信号通路中都不起作用。阐明特定的G蛋白，耦合钙离子通道与阿片类和肾上腺素能受体将有助于我们更好地了解这些受体如何调节突触传递的SG神经元支配cardiac muscle.AbstractCardiac function regulated in part by the sympathetic分支的自主神经系统通过星状神经节（SG）神经元。神经递质，如去甲肾上腺素（NA）和神经肽，包括伤害感受素（Noc），通过调节钙通道功能后，肾上腺素能和伤害感受素/FQ肽（NOP）阿片受体，分别影响SG神经元的兴奋性。Ca 2+通道的调节由Gβγ介导，但调节通道的特定Gβ亚基尚不清楚。在本研究中，小干扰RNA（siRNA）被用来沉默大鼠SG组织中天然表达的Gβ蛋白，并采用膜片钳技术的全细胞变体来检查肾上腺素能和NOP阿片受体与Ca 2+通道的偶联特异性。Western blotting分析表明，Gβ1、Gβ2和Gβ4均为天然表达。Gβ2或Gβ4的敲低导致NA-和Noc-介导的Ca 2+电流抑制显著降低，而Gβ1沉默则没有影响。然而，维持低水平的Gβ2导致Gβ4的表达增加，并伴随着肾上腺素能和阿片类信号通路调节Ca 2+通道的补偿。相反，Gβ4定向siRNA不伴随信号通路的补偿。最后，Gβ2和Gβ4的联合沉默阻止了任何额外的补偿机制。总之，我们的研究表明，在SG神经元中，Gβ2和Gβ4通常维持Ca 2+通道与受体的偶联，后者亚型负责维持两条通路的完整性。
Key point•Sympathetic stellate ganglion (SG) neurons that innervate cardiac muscle play an important role in regulating heart rate and contractility.•In this study, we examined which Gβ protein subunit couples Ca2+channels to opioid and adrenergic receptors expressed in SG neurons.•We show that Gβ2 and Gβ4 are important signalling elements that maintain the transduction pathway of both receptor subtypes and Ca2+channels, and how their expression levels are differentially compensated.•Our results also indicate that Gβ1 subunits do not appear to play a role in either signalling pathway.•The elucidation of specific G proteins that couple Ca2+channels with opioid and adrenergic receptors will help us better understand how these receptors regulate synaptic transmission of SG neurons that innervate cardiac muscle.AbstractCardiac function is regulated in part by the sympathetic branch of the autonomic nervous system via the stellate ganglion (SG) neurons. Neurotransmitters, such as noradrenaline (NA), and neuropeptides, including nociceptin (Noc), influence the excitability of SG neurons by modulating Ca2+channel function following activation of the adrenergic and nociceptin/orphanin FQ peptide (NOP) opioid receptors, respectively. The regulation of Ca2+channels is mediated by Gβγ, but the specific Gβ subunit that modulates the channels is not known. In the present study, small interference RNA (siRNA) was employed to silence the natively expressed Gβ proteins in rat SG tissue and to examine the coupling specificity of adrenergic and NOP opioid receptors to Ca2+channels employing the whole‐cell variant of the patch‐clamp technique. Western blotting analysis showed that Gβ1, Gβ2 and Gβ4 are natively expressed. The knockdown of Gβ2 or Gβ4 led to a significant decrease of the NA‐ and Noc‐mediated Ca2+current inhibition, while Gβ1 silencing was without effect. However, sustaining low levels of Gβ2 resulted in an increased expression of Gβ4 and a concomitant compensation of both adrenergic and opioid signalling pathways modulating Ca2+channels. Conversely, Gβ4‐directed siRNA was not accompanied with a compensation of the signalling pathway. Finally, the combined silencing of Gβ2 and Gβ4 prevented any additional compensatory mechanisms. Overall, our studies suggest that in SG neurons, Gβ2 and Gβ4 normally maintain the coupling of Ca2+channels with the receptors, with the latter subtype responsible for maintaining the integrity of both pathways.