多种G_q蛋白偶联受体激活后对KCNQ/M电流的作用及机制的研究
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摘要
G蛋白偶联受体(G protein-coupled-receptors,GPCRs)是目前发现的最大的细胞膜表面受体超家族,具有重要的生理病理学和药理学意义。其独特的结构特征和在信号转导中的重要作用决定了其可以作为很好的药物靶点。GPCRs特异性的激动剂及阻断剂具有良好的药物开发前景。事实上目前市场上超过一半的药物均是以GPCRs为靶点的。不同的GPCR通过和相应的G蛋白(G protein)偶联可以对细胞外多种刺激信号作出反应,在细胞内产生神经传递、味觉、嗅觉、视觉及细胞的新陈代谢、分化、增殖、分泌等一系列生理效应。G蛋白种类较多,但所有类型G蛋白都由3个不同的亚单位即α、β、γ所组成。α亚单位具有特异的GTP结合位点,有GTP酶活性。根据G蛋白的α亚单位的结构,可将其分为4个亚家族:G_s,G_(i/o),G_q和G_(12)。
     M电流最早于1980年由Brown和Admas在牛蛙颈上交感神经节中发现,是一种慢激活、非失活的电压依赖型外向钾离子电流,因其可被激活后的毒蕈碱受体(M受体)所抑制而得名。M电流的抑制将导致神经系统兴奋性升高。M通道的功能失调与良性家族性新生儿惊厥症(BFNCs)、阿尔茨海默氏病(Alzheimer)、癫痫等疾病密切相关。M通道的分子基础是KCNQ钾离子通道,目前已经发现了5种KCNQ亚型:KCNQ1~5,其中KCNQ2-5,尤其是KCNQ2/Q3参与构成M电流。
     在对M电流调节机制的研究中已经发现一些G_q蛋白偶联受体激活后能引起M电流的抑制。由G_q蛋白偶联受体介导的磷脂酶C(PLC)信号转导通路被认为是其抑制M电流的主要途径。目前已证明,G_(αq)蛋白激活后首先激活PLC_β,进而水解胞膜PIP_2,PIP_2水解生成两种第二信使IP_3与DAG,IP_3可引发细胞内质网钙库释放,而DAG则进一步激活PKC。PIP_2水解、PKC及细胞内钙离子均可能在GPCRs调节M电流过程中发挥了作用。然而,对于是否所有G_q蛋白偶联受体激活对KCNQ/M电流的调节作用是否利用同样的机制还不甚明了。
     目的:观察HEK293细胞中外源性表达的组胺(H1)、血管紧张素Ⅱ(AT1)、嘌呤(P2Y1和P2Y2)受体对共表达的KCNQ2/3通道电流的抑制作用,以细胞膜PIP_2及细胞内钙释放为主要观察点,研究抑制作用的信号通路机制,并为以后的实验打下基础。
     方法:用全细胞膜片钳记录电流变化:用激光共聚焦显微镜(LSCM)观测细胞膜PIP_2敏感荧光探针(PLC -PH-GFP)在细胞膜与细胞浆间的转位情况,进而了解PIP_2的水解情况;用LSCM及双波长比例法钙成像技术测定细胞内钙离子浓度变化。
     结果:(1)用全细胞膜片钳方法记录到的HEK293细胞表达的外源性的KCNQ2/3电流可以被共表达的H1、AT1、P2Y1和P2Y2受体激活后所抑制,H1、AT1、P2Y1和P2Y2激活对KCNQ2/3电流的抑制率分别为87.7%±6.9%(n=7),55.0%±4.9%(n=4),57.7%±5.1%(n=6)和62.0%±3.1%(n=6)。(2)LSCM观察HEK293细胞膜PIP_2水解情况:以上四种受体激动后均可明显见到荧光探针(PLC -PH-GFP)从胞膜处向胞浆处的转位,洗掉受体激动药物后,荧光探针又重新由胞浆转位到胞膜(复位),呈现一种可逆性变化。在PI4激酶抑制剂wortmannin持续存在的情况下,荧光探针由胞浆到胞膜的复位被抑制,说明荧光探针的复位是PI4激酶介导的PIP_2的再合成的结果。用PLC阻断剂U73122预先孵育细胞后,受体激活导致的由胞膜向胞浆的荧光转位不再发生,说明受体激活导致的荧光探针转位是PLC介导的PIP_2水解的结果。(3)用LSCM及双波长比例法钙成像技术测定细胞内钙离子浓度变化:以上四种受体激动后无论是否有无外钙存在,均可引起细胞内钙升高,这种作用可被U73122阻断。(4)组胺H1受体激动后抑制KCNQ2/3电流机制的研究:用全细胞膜片钳方法记录HEK293细胞表达的KCNQ2/3电流,观察激活表达的H1受体对KCNQ2/3电流抑制作用,并观察PLC阻断剂U-73122、PI4激酶阻断剂wortmannin和钙库耗竭剂thapsigargin对上述作用的影响,从而推断PIP_2及细胞内钙在H1受体激活抑制KCNQ2/3电流中的作用。PLC阻断剂U73122可使电流抑制率由74.5±0.6%(n=5)显著下降到7.1±0.6%(n=5,p<0.01),基本取消了H1受体激活对电流的抑制作用,说明H1受体是通过激活PLC对KCNQ2/3电流产生抑制的;P14激酶抑制剂wortmannin使电流被抑制后的恢复率由88.4±6.2%(n=7)显著下降到10.5±3.4%(n=8,p<0.01),说明PIP_2的再合成是组胺通过H1受体抑制KCNQ2/3电流后电流恢复的必要条件;内钙库耗竭剂thapsigargin应用前后电流抑制率分别为90.0±1.6%(n=6),88.6±3.9%(n=6,p>0.05),无显著性差别,说明细胞内钙的释放没有参与组胺H1受体抑制KCNQ2/3电流的过程。
     结论:结果表明在HEK293细胞中,H1、AT1、P2Y1和P2Y2受体均可抑制KCNQ2/3 M电流,上述受体激动后通过激活PLC,可以水解细胞膜上的PIP_2,且均可引起细胞内钙升高。H1受体及其他GPCRs激活后可能主要是通过激动PLC产生的细胞膜PIP_2水解,而不是细胞内钙来抑制KCNQ2/3电流的。
The G protein-coupled-receptors(GPCRs)are the largest superfamily of cell surface receptors,and have important pathophysiological and pharmacological significance.GPCRs play important roles in cellular signaling networks involving such processes as neurotransmission,taste,smell,vision,cellular metabolism,differentiation,growth and secretion.Different GPCRs respond to a wide variety of different external stimulants and initiate a wide spectrum of intracellular responses by activating a number of different GTP binding proteins(G proteins).GPCRs are practical and potential drug targets due to the important physiological roles they play,and due to the nature of signaling transduction pathway they initiate.Thus agonists or antagonists of GPCRs are being used as,or have potential to become new drugs.In fact,GPCRs are targets for more than half of the current therapeutic agents on the market now.There are many kinds of G proteins but all are composed ofα、β、γsubunits.Theαsubunit has the GTPase activity and can hydrolyze bound GTP.According to the structure ofαsubunit,G proteins can be divided into four sub-families:G_s, G_(i/o),G_q and G_(12).
     M current was first discovered in bullfrog sympathetic neurons by Brown and Admas in 1980.It is a slowly activating,noninactivating, voltage-dependent potassium current.It is named M current because of its suppression by muscarinic receptor activation. Blocking of M current will result in hyperexcitability of the neuronal system.The dysfunction of M channel is closely associated with diseases like benign neonatal familial convulsions(BFNCs), Alzheimer,epilepsy,etc.The molecular basis of M current is KCNQ potassium channels.So far five members of KCNQ(KCNQ1~5) have been found.Among them,KCNQ2-5,specially KCNQ2/Q3 heteromultimers are believed to form neuronal M currents.
     Ample evidence demonstrated that activation of some G_q protein-coupled-receptors will result in KCNQ/M current inhibition.The PLC signaling pathway is believed to mediate M current inhibition during G_q protein-coupled-receptor activation.PLC_β,when stimulated by G_(αq)proteins,hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP_2),yielding two intracellular second messengers IP_3 and DAG.IP_3 then trigger calcium release from endoplasmic reticulum,which in turn are involved in varieties of cell functions. DAG activates PKC.Membrane PIP_2 hydrolysis,PKC and intracellular calcium have all been demonstrated to be involved in G_q protein-coupled-receptor-mediated M current regulations.However, it is not clear if all G_q protein-coupled-receptors modulate KCNQ/M currents through same mechanism.
     Objective:To study the effect of G_q protein-coupled-receptor on KCNQ2/3 channel currents expressed in HEK293 cells.GPCRs observed in the study includes:histamine(HI),angiotensinⅡ(AT1), purine(P2Y1,P2Y2)receptors.The study will focus on two key signaling molecules:membrane PIP_2 and intracellular calcium,to study their role in KCNQ/M current inhibition induced by GPCR activation.This study will lay a foundation for future investigation.
     Methods:Whole cell patch clamp technique will be used to record KCNQ currents.Laser scanning confocal microscopy(LSCM) will be used to monitor translocation of PIP_2 sensitive florescence probe(PLC -PH-GFP)between the membrane and the cytosol thus to monitor membrane PIP_2 hydrolysis.LSCM and ratio-imaging microscopy technique will be used to monitor intracellular Ca~(2+) release.
     Results:(1)Activation of H1、AT1、P2Y1 and P2Y2 receptors all inhibited co-expressed KCNQ2/3 channel currents recorded using whole cell patch clamp in HEK293 cells.Activation of H1、AT1、P2Y1 and P2Y2 receptors inhibited KCNQ2/3 currents by 87.7%±6.9%(n=7),55.0%±4.9%(n=4),57.7%±5.1%(n=6)and 62.0%±3.1%(n=6),respectively.(2)For membrane PIP_2 hydrolysis study,application of agonists for these four GPCRs caused a translocation of the fluorescent probe from the membrane to the cytosol which was reversible after washout of the agonists. Wortmannin,a blocker of PI4 kinase,blocked the recovery of the florescence from the cytosol to the membrane,indicating the recovery is the result of PI4 kinase-mediated PIP_2 resynthesis. U73122,a blocker of PLC,totally abolished fluorescent translocation from the membrane to the cytosol induced by activation of the GPCRs,indicating the translocation is a result of PLC-mediated membrane PIP_2 hydrolysis.(3)Intracellular calcium([Ca~(2+)]_i) monitored using LSCM and ratio-imaging microscopy system demonstrated a rising of[Ca~(2+)]_i in responding to activation of receptors expressed in HEK293 cells,with or without presence of extracellular calcium.[Ca~(2+)]_i rising was completely abolished by treatment with U-73122.(4)Inhibition of KCNQ2/3 currents by activation of histamine H1 receptor in HEK293 cells is due to hydrolysis of membrane PIP_2 and is independent of[Ca~(2+)]_i signals. U-73122,a PLC inhibitor,antagonized histamine-induced KCNQ2/3 current inhibition;the inhibition rate was reduced significantly from 88.4±6.2%(n=7)to 10.5±3.4%(n=8,p<0.01).Treatment with PI4 kinase inhibitor wortmannin,which blocks the synthesis of PIP_2, made histamine-induced KCNQ2/3 currents inhibition irreversible; the recovery rate was reduced significantly from 74.5±0.6%(n=5)to 7.1±0.6%(n=5,p<0.01).Histamine-induced inhibition of KCNQ2/3 currents was not affected by thapsigargin,which depletes internal Ca~(2+)stores;application of histamine after thapisgargin treatment still produced a remarkable inhibition of 88.6±3.9%(n=6),which is not significantly different from a 90.0±1.6%(n=6)inhibition in the absence of thapisgargin.
     Conclusion:The results demonstrate that in HEK 293 cells, activation of four types of GPCRs,H1、AT1、P2Y1 and P2Y2,all inhibited co-expressed KCNQ2/3 channel currents.Activation of these receptors leads to PIP_2 hydrolysis and intracellular calcium increase through stimulation of PLC.Activation of H1 and other GPCR.s in HEK293 cells inhibits KCNQ2/3 current possibly through PIP_2 hydrolysis rather than[Ca~(2+)]_i signaling.
引文
1 Milligan G.Agonist regulation of cellular G protein levels and distribution;mechanisms and functional implications.Trends Pharmacol Sci,1993,14:413-41
    2 Hill SJ.G-protein-coupled receptors:past,present and future.Br J Pharmacol,2006,147,1:S27-37
    3 Brown BS,SP Yu.Modulation and genetic identification of the M channel.Prog Biophys Mol Biol,2000,73:135-166
    4 Holt JR and Corey DP,Ion channel defects in hereditary hearing loss.Neuron,1999,22:217-219
    5 Cassell JF,EM McLachlan.Muscarinic agonists block five different potassium conductances in guinea-pig sympathetic neurones.Br J Pharmacol,1987,91:259-261
    6 Passmore GM.Dorsal root ganglion neurones in culture:a model system for identifying novel analgesic targets? J Pharmacol Toxicol Methods,2005,51:201-208
    7 Shah MM,M Mistry,SJ Marsh,et al.Molecular correlates of the M-current in cultured rat hippocampal neurons.J Physiol,2002,544:29-37
    8 Jon Robbins.KCNQ potassium channels:physiology,pathophysiology,and pharmacology.Pharmacology & Therapeutics, 2001, 90:1-19
    
    9 Surti TS, Jan LY. A potassium channel, the M-channel, as a therapeutic target. Curr Opin Investig Drugs, 2005, 6:704-11
    
    10 Wickenden AD, Roeloffs R, McNaughton Smith G, et al. KCNQ potassium channels: drug targets for the treatment of epilepsy and pain. Expert Opin Ther Patents, 2004,14:1-13
    
    11 Martire M, Castaldo P, D'Amico M, et al. M channels containing KCNQ2 subunits modulate norepinephrine, aspartate, and GABA release from hippocampal nerve terminals. J Neurosci. 2004, 24 :592 - 597
    
    12 Suh BC, Horowitz LF, Hirdes W , et al. Regulation of KCNQ2/KCNQ3 current by G protein cycling: the kinetics of receptor-mediated signaling by Gq. J Gen Physiol, 2004, 123(6):663-683
    
    13 Ford CP, Stemkowski PL, Light PE, et al. Experiments to test the role of phosphatidylinositol 4,5-bisphosphate in neurotransmitter-induced M-channel closure in bullfrog sympathetic neurons. J Neurosci, 2003, 23 (12):4931-4941
    
    14 Ikeda SR, Kammol-Lermeier PJ. M current mystery messenger revealed. Neuron, 2002, 35(3):411-412
    
    15 Yu SP, O'Malley DM, Adams PR. Regulation of M current by intracellular calcium in bullfrog sympathetic ganglion neurons. J Neurosci, 1994, 14(6):3487-3499
    
    16 Cruzblanca H, Koh DS, Hille B. Bradykinin inhibits M current via phospholipase C and Ca2+ release from IP3-sensitive Ca2+ stores in rat sympathetic neurons. Proc Natl Acad Sci U S A, 1998,95(12):7151-7156
    
    17 Du XN, Zhang HL, et al. Characteristic interactions with PIP2 determine regulation of Kir channels by diverse modulators. J Biol Chem, 2004,279(36):37271-37281
    
    18 Zhang H., Craciun LC, Mirshahi T, et al. PIP2 Activates KCNQ Channels, and Its Hydrolysis Underlies Receptor-Mediated Inhibition of M Currents. Neuron, 2003, 37(6):963-975
    
    19 Zhang HL, He C, Yan XX, Mirshahi T et al. Activation of inwardly rectifying K+ channels by distinct PtdIns(4,5)P2 interactions. Nature Cell Biology, 1999, 1:183-188
    
    20 Haley JE, Abogadie FC, Fernandez-Fernandez JM, et al. Bradykinin, but not muscarinic, inhibition of M-current in rat sympathetic ganglion neurons involves phospholipase C-beta 4. J Neurosci, 2000, 20(21):RC105
    
    21 Suh BC, Hille B. Recovery from muscarinic modulation of M current channels requires phosphatidylinositol 4, 5-bisphosphate synthesis. Neuron, 2002, 35(3):507-520
    
    22 Zaika O, Tolstykh GP, and Shapiro MS. Inositol triphosphate-mediated Ca2+ signals direct purinergic P2Y receptor regulation of neuronal ion channels. J Neurosci, 2007, 27: 8914-8926
    
    23 Cruzblanca H, DS KohB Hille. Bradykinin inhibits M current via phospholipase C and Ca2+ release from IP3-sensitive Ca2+ stores in rat sympathetic neurons. Proc Natl Acad Sci U S A, 1998, 95:7151-7156
    
    24 Gamper N, Shapiro MS. Calmodulin mediates Ca2+-dependent modulation of M-type K+ channels. J Gen Physiol, 2003,
    25 Guo J, GG Schofield. Histamine inhibits KCNQ2/KCNQ3 channel current via recombinant histamine H1 receptors. Neurosci Lett, 2002, 328:285-288
    
    26 Zoltan Gerevich, Sebestyen J. Borvendeg, Wolfgang Schro'der, et al. Inhibition of N-Type Voltage-Activated Calcium Channels in Rat Dorsal Root Ganglion Neurons by P2Y Receptors Is a Possible Mechanism of ADP-Induced Analgesia. Journal of Neuroscience, 2004, 24(4):797- 807
    
    27 Bofill-Cardona E, N Vartian, C Nanoff, et al. Two different signaling mechanisms involved in the excitation of rat sympathetic neurons by uridine nucleotides. Mol Pharmacol, 2000,57:1165-1172
    
    28 S J.Hill, C R.Ganellin, H.Timmerman, et al. International Union of Pharmacology. XIILClassification of Histamine Receptors. Pharmacol Rev. 1997, 49:253-278
    
    29 M.DE Gasparo, K J.Catt, T.Inagami, et al. International Union of Pharmacology. XXIII. The Angiotensin II Receptors. Pharmacol Rev, 2000, 52:415-472
    
    30 DUBYAK, G.R. & EL-MOATASSIM. Signal transduction via P2-purinoceptors for extracellular ATP and other nucleotides. Am. J. Physiol, 1993, 265:C577-C606
    
    31 Varnai P, Rother K. I., Balla T. Phosphatidylinositol 3-kinase-dependent membrand association of the Bruton's tyrosine kinase pleckstrin homology domain visualized in single living cells. J. Biol. Chem. 1999,274: 10983-10989
    32 Nakanishi S, Catt k. J, Balla T. A wortmannin-sensitive phosphatidylinositol 4-kinase that regulates hormone-sensitive pools of inositolphospholipids. Proc. Natl. Acad. Sci. USA 1995, 92:5317-5321
    
    33 Horowitz LF, Hirdes W, Suh BC, et al. Phospholipase C in living cells: activation, inhibition, Ca2+ requirement, and regulation of M current. J Gen Physiol, 2005,126:243-262
    
    34 Ford CP, Stemkowski PL, and Smith PA. Possible role of phosphatidylinositol4, 5 bisphosphate in luteinizing hormone releasing hormone-mediated M-current inhibition in bullfrog sympathetic neurons. Eur J Neurosci, 2004,20: 2990-2998
    
    35 Rasmussen U , Broogger Christensen S , Sandberg F. Thapsigargine and thapsigargicine, two new histamine liberators from Thapsia garganica L. Acta Pharm Suec, 1978, 15: 133-140
    
    36 Thastrup O, Dawson AP, Scharff O, et al. Thapsigargin, a novel molecular probe for studying intracellular calcium release and storage. Agents Actions, 1989, 27: 17-23
    
    37 Shapiro MS, LP Wollmuth, B Hille. Angiotensin II inhibits calcium and M current channels in rat sympathetic neurons via G proteins. Neuron, 1994, 12:1319-1329
    
    38 Maljevic S, Lerche C, Seebohm G, et al. C-terminal interaction of KCNQ2 and KCNQ3 K+ channels. J Physiol. 2003, 548(Pt 2):353-60
    
    39 Cruzblanca H, DS KohB Hille. Bradykinin inhibits M current via phospholipase C and Ca2+ release from IP3-sensitive Ca2+ stores in rat sympathetic neurons. Proc Natl Acad Sci U S A, 1998, 95:7151-7156
    
    40 Kim BM, Lee SH, Shim WS, et al. Histamine-induced Ca2+ influx via the PLA/lipoxygenase/TRPV1 pathway in rat sensory neurons. Neurosci Lett, 2004, 361: 159-162
    
    41 Calvert JA, Atterbury-Thomas AE, Leon C, et al. Evidence for P2Y1, P2Y2, P2Y6 and atypical UTP-sensitive receptors coupled to rises in intracellular calcium in mouse cultured superior cervical ganglion neurons and glia. Br J Pharmacol, 2004, 143:525-532
    
    42 Hirose K, kadowaki S, Tanabe M et al. Spatiotemporal dynamics of inositol 1,4,5-trisphosphate that underlies complex Ca2+ mobilization patterns. Science 1999, 284: 1527-1530
    
    43 Bleasdale J.E, Thakur N.R, Gremban R.S et al. Selective inhibition of receptor-coupled phospholipase C-dependent processes in human platelets and polymorphonuclear neutrophils. J Pharm Exp Therap 1990, 255:756-768
    
    44 Zhou Z, Nehere E. Mobile and immobile calcium buffers in bovine adrenal chromaffin cells. J Physiol, 1993,469:245-273
    
    45 Takahashi A, Camacho P, Lechleiter JD, et al. Measurement of intracellular calcium. Physiol Rev, 1999, 79:1089-1125 Thapsigargin , a novel molecular probe for studying intracellular calcium release and storage. Agents Actions, 1989,27: 17-23
    
    37 Shapiro MS, LP Wollmuth, B Hille. Angiotensin II inhibits calcium and M current channels in rat sympathetic neurons via G proteins. Neuron, 1994, 12:1319-1329
    
    38 Maljevic S, Lerche C, Seebohm G, et al. C-terminal interaction of KCNQ2 and KCNQ3 K+ channels. J Physiol. 2003,548(Pt2):353-60
    
    39 Cruzblanca H, DS KohB Hille. Bradykinin inhibits M current via phospholipase C and Ca2+ release from IPs-sensitive Ca2+ stores in rat sympathetic neurons. Proc Natl Acad Sci U S A, 1998, 95:7151-7156
    
    40 Kim BM, Lee SH, Shim WS, et al. Histamine-induced Ca2+ influx via the PLA/lipoxygenase/TRPV1 pathway in rat sensory neurons. Neurosci Lett, 2004, 361: 159-162
    
    41 Calvert JA, Atterbury-Thomas AE, Leon C, et al. Evidence for P2Y1, P2Y2, P2Y6 and atypical UTP-sensitive receptors coupled to rises in intracellular calcium in mouse cultured superior cervical ganglion neurons and glia. Br J Pharmacol, 2004, 143:525-532
    
    42 Hirose K, kadowaki S, Tanabe M et al. Spatiotemporal dynamics of inositol 1,4,5-trisphosphate that underlies complex Ca2+ mobilization patterns. Science 1999, 284: 1527-1530
    
    43 Bleasdale J.E, Thakur N.R, Gremban R.S et al. Selective inhibition of receptor-coupled phospholipase C-dependent processes in human platelets and polymorphonuclear neutrophils. J Pharm Exp Therap 1990, 255:756-768
    
    44 Zhou Z, Nehere E. Mobile and immobile calcium buffers in bovine adrenal chromaffin cells. J Physiol, 1993, 469:245-273
    
    45 Takahashi A, Camacho P, Lechleiter JD, et al. Measurement of intracellular calcium. Physiol Rev, 1999,79:1089-1125
    1 Brown DA,PR Adams.Muscarinic suppression of a novel voltage-sensitive K~+ current in a vertebrate neurone.Nature,1980,283:673-676
    2 Brown BS,SP Yu.Modulation and genetic identification of the M channel.Prog Biophys Mol Biol.2000,73:135-166
    3 Holt JR and Corey DP,Ion channel defects in hereditary hearing loss.Neuron,1999,22:217-219
    4 Passmore GM.Dorsal root ganglion neurones in culture:a model system for identifying novel analgesic targets? J Pharmacol Toxicol Methods,2005,51:201-20
    5 Shah MM,M Mistry,SJ Marsh,et al.Molecular correlates of the M-current in cultured rat hippocampal neurons.J Physiol,2002,544:29-37
    6 Cassell JF,EM McLachlan.Muscarinic agonists block five different potassium conductances in guinea-pig sympathetic neurones.Br J Pharmacol,1987,91:259-261
    7 Surti TS,Jan LY.A potassium channel,the M-channel,as a therapeutic target.Curr Opin Investig Drugs,2005,6:704-11
    8 Seebohm G,Westenskow P,Sanguinetti MC.Mutation of colocalized residues of the pore helix and transmembrane segments S5 and S6 disrupt deactivation and modify inactivation of KCNQ1 K+ channels. J Physiol, 2005, 563:359-68
    
    9 Wickenden AD, Roeloffs R, McNaughton Smith G, et al. KCNQ potassium channels: drug targets for the treatment of epilepsy and pain. Expert Opin Ther Patents, 2004,14:1-13
    
    10 Schwake M, Athanasiadu D, Beimgraben C, et al. Structural determinants of M type KCNQ(Kv7) K+ channel assembly. J Neurosci, 2006; 26:57-66
    
    11 Wickenden AD, Ye F, Liu Y, et al. KCNQ channel expression in rat DRG following nerve ligation Soc. Neurosci. Abstract, 2002,454.7
    
    12 Wang HS, Z Pan, W Shi, et al. KCNQ2 and KCNQ3 potassium channel subunits: molecular correlates of the M-channel. Science, 1998,282:1890-1893
    
    13 Shapiro MS, JP Roche, EJ Kaftan, et al. Reconstitution of muscarinic modulation of the KCNQ2/KCNQ3 K(+) channels that underlie the neuronal M current. J Neurosci, 2000, 20:1710-1721
    
    14 Selyanko, A. A., Hadley, J. K., Wood, et al. Inhibition of KCNQ1- 4 potassium channels expressed in mammalian cells via Ml muscarinic acetylcholine receptors. J Physiol (Lond), 2000, 522:349-355
    
    15 Cooper EC, Jan LY. M-channels: neurological diseases, neuromodulation, and drug development. Arch Neurol, 2003, 60:496-500
    
    16 Marrion NV. Control of M-current. Annu Rev Physiol, 1997, 59:483-504
    17 Martire M, Castaldo P, DAmico M, et al. M channels containing KCNQ2 subunits modulate norepinephrine, aspartate, and GABA release from hippocampal nerve terminals. J Neurosci, 2004, 24:592-7
    
    18 Biervert, C, Schroeder, B. C, et al. A potassium channel mutation in neonatal epilepsy. Science, 1998,279:403-406
    
    19 Rivera Arconada I, Martinez Gomez J, Lopez Garcia JA. M current modulators alter rat spinal nociceptive transmission: an electrophysiological study in vitro. Neuropharmacology, 2004, 46:598-60
    
    20 Devaux JJ, Kleopa KA, Cooper EC et al. KCNQ2 is a nodal K+ channel. J. Neurosci. 2004, 24(5): 1236-1244.
    
    21 Bassi MT, Balottin U, Panzeri C et al. Functional analysis of novel KCNQ2 and KCNQ3 gene variants found in a large pedigree with benign familial neonatal convulsions (BFNC). Neurogenetics, 2005, 19:1-9
    
    22 Eid Jr CN, Rose GM. Cognition enhancement strategies by ion channel modulation of neurotransmission. Curr Pharmceut Design, 1999, 5:345-61
    
    23 Filippov AK, J Simon, EA Barnard, et al. Coupling of the nucleotide P2Y4 receptor to neuronal ion channels. Br J Pharmacol, 2003,138:400-406
    
    24 Shapiro MS, LP Wollmuth, B Hille. Angiotensin II inhibits calcium and M current channels in rat sympathetic neurons via G proteins. Neuron, 1994, 12:1319-1329
    
    25 Wallace DJ, C ChenPD Marley. Histamine promotes excitability in bovine adrenal chromaffin cells by inhibiting an M-current. J Physiol, 2002, 540:921-939
    
    26 Delmas P, Brown DA. Pathways modulating neural KCNQ/M (Kv7) potassium channels. Nat Rev Neurosci 2005, 6(11):850-62.
    
    27 Du XN, Zhang HL, et al. Characteristic interactions with PIP2 determine regulation of Kir channels by diverse modulators. J Biol Chem, 2004, 279(36):37271-37281
    
    28 Zhang H., Craciun LC, Mirshahi T et al. PIP2 Activates KCNQ Channels, and Its Hydrolysis Underlies Receptor-Mediated Inhibition of M Currents. Neuron, 2003, 37(6):963-975
    
    29 Zhang HL, He C, Yan XX, et al. Activation of inwardly rectifying K+ channels by distinct PtdIns(4,5)P2 interactions. Nature Cell Biology, 1999,1:183-188
    
    30 Selyanko, Brown, D. A. Intracellular calcium directly inhibits potassium M channels in excised membrane patches from rat sympathetic neurons. Neuron, 1996, 16:151-162.
    
    31 Gamper, N. & Shapiro, M. S. Calmodulin mediates Ca2+- dependent modulation of M-type K+ channels. J. Gen. Physiol. 2003, 122:17-31
    
    32 Cruzblanca, H, Koh, D. S., et al. Bradykinin inhibits M current via phospholipase C and Ca2+ release from IP3-sensitive Ca2+ stores in rat sympathetic neurons. Proc. Natl Acad. Sci. 1998, USA 95:7151-7156
    
    33 Suh BC and Hille B. Regulation of ion channels by phosphatidylinositol 4, 5-bisphosphate. Current Opinion in Neurobiology. 2005, 15:370-378
    34 Zaika O, Lara LS, Gamper N et al. Angiotensin II regulates neuronal excitability via phosphatidylinositol 4,5-bisphosphate-dependent modulation of Kv7 (M-type) K+ channels. J Physiol, 2006, 575:49-67
    
    35 Wen, H. & Levitan, I. B. Calmodulin is an auxiliary subunit of KCNQ2/3 potassium channels. J. Neurosci. 2002,22:7991-8001

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