Differential phospholipase C-dependent modulation of TASK and TREK two-pore domain K+ channels in rat thalamocortical relay neurons
Differential phospholipase C-dependent modulation of TASK and TREK two-pore domain K+ channels in rat thalamocortical relay neurons
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DOI：
10.1113/jphysiol.2014.276527
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发表时间：
2015-01-01
影响因子：
5.5
通讯作者：
Budde, Thomas
中科院分区：
文献类型：
--
作者：
Bista, Pawan;Pawlowski, Matthias;Budde, Thomas
双孔域钾通道（K-2P）的活性调节丘脑皮质（TC）神经元的兴奋性和放电模式。特别是，由于与磷酸肌苷特异性磷脂酶ec （PLC）偶联的毒瘤碱ACh受体（machr）的刺激，抑制与酸敏感K+ (TASK)相关的双孔域弱内向纠流K+通道（TWIK）和与TWIK相关的K+ (TREK)通道，诱导从爆发到强直放电的转变。通过全细胞膜片钳方法，研究了细胞膜结合的第二信使分子磷脂酰肌醇4,5-二磷酸（PIP2）和二酰基甘油（DAG）在PLC下游的作用。采用静外向电流（I-SO）监测TC神经元TASK和TREK通道电流。通过利用不同的策略来改变TC神经元细胞内PIP2水平，我们在这里表明（通过新霉素）清除PIP2导致对I-SO的毒蕈碱效应增加，而PIP2可用性的增加（包括到斑块移液器；组蛋白载体）减少毒蕈碱信号传导。毒蕈碱的抑制程度具体取决于磷脂酰肌醇磷酸（PIP）和PIP2，而不取决于其他磷脂（磷脂酸、磷脂酰丝氨酸）。特异性阻滞剂的使用表明PIP2靶向TREK通道而非TASK通道。此外，我们证明了TASK通道的抑制是由DAG类似物1-油基-2-乙酰基-sn-甘油（OAG）诱导的。在当前箝位条件下，machr和PLC的激活以及OAG的应用导致了膜去极化，而PIP2通过组蛋白载体的应用诱导了超极化。这些结果表明，在原生神经元中，PIP2和DAG在K-2P通道调制中的不同作用，允许在MAChR刺激后对TREK（通过PIP2耗竭）和TASK（通过DAG）通道进行微调抑制。
The activity of two-pore domain potassium channels (K-2P) regulates the excitability and firing modes of thalamocortical (TC) neurons. In particular, the inhibition of two-pore domain weakly inwardly rectifying K+ channel (TWIK)-related acid-sensitive K+ (TASK) channels and TWIK-related K+ (TREK) channels, as a consequence of the stimulation of muscarinic ACh receptors (MAChRs) which are coupled to phosphoinositide-specific phospholipaseC (PLC), induces a shift from burst to tonic firing. By using a whole cell patch-clamp approach, the contribution of the membrane-bound second messenger molecules phosphatidylinositol 4,5-bisphosphate (PIP2) and diacylglycerol (DAG) acting downstream of PLC was probed. The standing outward current (I-SO) was used to monitor the current through TASK and TREK channels in TC neurons. By exploiting different manoeuvres to change the intracellular PIP2 level in TC neurons, we here show that the scavenging of PIP2 (by neomycin) results in an increased muscarinic effect on I-SO whereas increased availability of PIP2 (inclusion to the patch pipette; histone-based carrier) decreased muscarinic signalling. The degree of muscarinic inhibition specifically depends on phosphatidylinositol phosphate (PIP) and PIP2 but no other phospholipids (phosphatidic acid, phosphatidylserine). The use of specific blockers revealed that PIP2 is targeting TREK but not TASK channels. Furthermore, we demonstrate that the inhibition of TASK channels is induced by the application of the DAG analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG). Under current clamp conditions the activation of MAChRs and PLC as well as the application of OAG resulted in membrane depolarization, while PIP2 application via histone carrier induced a hyperpolarization. These results demonstrate a differential role of PIP2 and DAG in K-2P channel modulation in native neurons which allows a fine-tuned inhibition of TREK (via PIP2 depletion) and TASK (via DAG) channels following MAChR stimulation.