ERK/MAPK pathway regulates GABAA receptors
ERK/MAPK pathway regulates GABAA receptors
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DOI：
10.1002/neu.20327
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发表时间：
2006-11-01
期刊：
影响因子：
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通讯作者：
Singh, Meharvan
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作者：
Bell-Horner, Cathy L.;Dohi, Akiko;Singh, Meharvan
GABA(A)受体是一种配体门控离子通道，其功能和活性可以通过配体结合来调节，也可以通过组成GABA(A)受体五聚体的特定亚基的磷酸化间接影响。关于磷酸化，大多数研究集中在0或7亚基上，而α亚基作为信号激酶的相关靶标的作用在很大程度上是未知的。有趣的是，我们在几乎所有已知的GABA(a)受体的α亚基（包括普遍表达的α 1亚基）中发现了一个假定的细胞外信号调节激酶（ERK）的磷酸化位点，ERK是MAPK途径的关键效应物。为了确定这个假定的ERK磷酸化位点是否与功能相关，我们评估了ERK抑制（通过药理抑制其上游激酶MEK）是否会改变gaba门控电流。通过稳定转染α - 1 β - 2 γ - 2形式GABA(A)受体的HEK293细胞，我们发现UO126降低了ERK的基础磷酸化，并导致GABA诱导的峰值电流振幅增强。此外，gaba门控电流的增强需要一个完整的细胞内环境，因为它在穿孔片记录（保留细胞内环境）中是稳健的，但在传统的全细胞记录（透析细胞质内容物）中缺乏，支持细胞内信号通路的参与。最后，ERK磷酸化位点（T375 -> A）的突变阻止了uo126诱导的gaba门控电流的增强。总的来说，我们的研究结果表明MAPK通路是GABA(a)受体功能的负调节因子，其对GABA门控电流的影响可能是通过α亚基的磷酸化介导的。(c) 2006 Wiley期刊公司
The GABA(A) receptor is a ligand-gated ion channel whose function and activity can be regulated by ligand binding or alternatively may be influenced indirectly through the phosphorylation of specific subunits that comprise the GABA(A) receptor pentamer. With respect to phosphorylation, most studies have focused on either 0 or 7 subunits, whereas the role of the alpha subunit as a relevant target of signaling kinases is largely unknown. Interestingly, we found a putative phosphorylation site for extracellular-signal regulated kinase (ERK), a key effector of the MAPK pathway, in almost all known alpha subunits of the GABA(A) receptor, including the ubiquitously expressed alpha 1 subunit. To determine whether this putative ERK phosphorylation site was functionally relevant, we evaluated if ERK inhibition (through pharmacological inhibition of its upstream kinase, MEK) altered GABA-gated currents. Using HEK293 cells stably transfected with the alpha 1 beta 2 gamma 2 form of the GABA(A) receptor, we found that UO126 reduced basal ERK phosphorylation and resulted in an enhancement of GABA-induced peak current amplitudes. Further, the enhancement of GABA-gated currents required an intact intracellular environment as it was robust in perforated patch recordings (which preserves the intracellular milieu), but absent in conventional whole-cell recordings (which dialyzes the cytosolic contents), supporting the involvement of an intracellular signaling pathway. Finally, mutation of the ERK phosphorylation site (T375 -> A) prevented the UO126-induced enhancement of GABA-gated currents. Collectively, our results implicate the MAPK pathway as a negative modulator of GABA(A) receptor function, whose influence on GABA-gated currents may be mediated by phosphorylation of the alpha subunit. (c) 2006 Wiley Periodicals, Inc.