Type 4 Phosphodiesterase Plays Different Integrating Roles in Different Cellular Domains in Pyramidal Cortical Neurons
Type 4 Phosphodiesterase Plays Different Integrating Roles in Different Cellular Domains in Pyramidal Cortical Neurons
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DOI：
10.1523/jneurosci.5851-09.2010
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发表时间：
2010-04-28
影响因子：
5.3
通讯作者：
Vincent, Pierre
中科院分区：
文献类型：
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作者：
Castro, Liliana R. V.;Gervasi, Nicolas;Vincent, Pierre
我们通过对表达生物传感器的雄性小鼠锥体皮质神经元进行实时成像，以监测cAMP水平(Epac1-Camps和Epac2-Camps 300)或PKA活性(AKAR2)，研究了磷酸二酯酶(PDE)在β-肾上腺素能刺激后cAMP信号和蛋白激酶A(PKA)活性整合中的作用。在SOMA中，异丙肾上腺素(ISO)将PKA信号增加到Forsklin最大反应的大约一半，具有特征的β(1)药理和EC50为4.5 nM。这种反应与亚微摩尔范围内的游离cAMP水平有关。特异性的4型PDE(PDE4)抑制剂罗利普兰单独作用很小，但强烈增强了对ISO的PKA反应。其他PDE的阻断剂均不起作用。因此，PDE4在将β(1)-肾上腺素能信号从细胞膜传播到体细胞胞浆的过程中起到了刹车的作用。亚膜结构域的结果明显不同，无论是用与慢速AHP相关的PKA敏感钾电流记录的，还是用小的远端树突的双光子成像记录的。对ISO的反应比在胞浆中的反应强。这与cAMP/PKA信号在膜上的强信号是一致的，正如电生理学所显示的那样，并且在具有高表面积/体积比的细胞域中受到青睐，其中该信号通过成像被检测到。罗利普兰本身也产生了强烈的cAMP/PKA信号，揭示了补药cAMP的产生。因此，PDE4似乎是一个重要的整合因子，在不同的亚细胞结构域中具有不同的生理意义。
We investigated the role of phosphodiesterases (PDEs) in the integration of cAMP signals and protein kinase A (PKA) activity following beta-adrenergic stimulation, by carrying out real-time imaging of male mouse pyramidal cortical neurons expressing biosensors to monitor cAMP levels (Epac1-camps and Epac2-camps300) or PKA activity (AKAR2). In the soma, isoproterenol (ISO) increased the PKA signal to approximately half the maximal response obtained with forskolin, with a characteristic beta(1) pharmacology and an EC50 of 4.5 nM. This response was related to free cAMP levels in the submicromolar range. The specific type 4 PDE (PDE4) inhibitor rolipram had a very small effect alone, but strongly potentiated the PKA response to ISO. Blockers of other PDEs had no effect. PDE4 thus acts as a brake in the propagation of the beta(1)-adrenergic signal from the membrane to the bulk somatic cytosol. The results for a submembrane domain were markedly different, whether recorded with a PKA-sensitive potassium current related to the slow AHP or by two-photon imaging of small distal dendrites. The responses to ISO were stronger than in the bulk cytosol. This is consistent with the cAMP/PKA signal being strong at the membrane, as shown by electrophysiology, and favored in cellular domains with a high surface area to volume ratio, in which this signal was detected by imaging. Rolipram alone also produced a strong cAMP/PKA signal, revealing tonic cAMP production. PDE4 thus appears as a crucial integrator with different physiological implications in different subcellular domains.