WNK1-regulated inhibitory phosphorylation of the KCC2 cotransporter maintains the depolarizing action of GABA in immature neurons
WNK1-regulated inhibitory phosphorylation of the KCC2 cotransporter maintains the depolarizing action of GABA in immature neurons
复制标题
DOI：
10.1126/scisignal.aaa0354
复制
发表时间：
2015-06-30
影响因子：
7.3
通讯作者：
Medina, Igor
中科院分区：
文献类型：
--
作者：
Friedel, Perrine;Kahle, Kristopher T.;Medina, Igor
激活Cl-可渗透的γ-氨基丁酸A型（GABA（A））受体在成熟神经元中引起突触抑制，但在未成熟神经元中引起兴奋。这种GABA功能的发育“开关”依赖于KCC 2介导的神经元内Cl-浓度的出生后降低，KCC 2是一种Cl-挤压K+-Cl-协同转运蛋白。我们发现丝氨酸-苏氨酸激酶WNK 1 [不含赖氨酸（K）]在发育中的小鼠大脑中与KCC 2形成物理复合物。显性负突变，遗传耗竭，或化学抑制WNK 1在未成熟的神经元引发超极化转变GABA活性增强KCC 2介导的Cl-挤出。KCC 2活性的这种增加是由于KCC 2在两个C-末端苏氨酸Thr（906）和Thr（1007）处的抑制性磷酸化减少所致。Thr（906）和Thr（1007）的磷酸化在未成熟神经元中比成熟神经元中增加。总之，这些数据提供了深入了解的机制，在未成熟的神经元中调节Cl-稳态，并表明WNK 1调节的KCC 2磷酸化的变化有助于发育兴奋性抑制GABA序列。
Activation of Cl--permeable gamma-aminobutyric acid type A (GABA(A)) receptors elicits synaptic inhibition in mature neurons but excitation in immature neurons. This developmental "switch" in the GABA function depends on a postnatal decrease in intraneuronal Cl- concentration mediated by KCC2, a Cl--extruding K+-Cl- cotransporter. We showed that the serine-threonine kinase WNK1 [with no lysine (K)] forms a physical complex with KCC2 in the developing mouse brain. Dominant-negative mutation, genetic depletion, or chemical inhibition of WNK1 in immature neurons triggered a hyperpolarizing shift in GABA activity by enhancing KCC2-mediated Cl- extrusion. This increase in KCC2 activity resulted from reduced inhibitory phosphorylation of KCC2 at two C-terminal threonines, Thr(906) and Thr(1007). Phosphorylation of both Thr(906) and Thr(1007) was increased in immature versus mature neurons. Together, these data provide insight into the mechanism regulating Cl- homeostasis in immature neurons, and suggest that WNK1-regulated changes in KCC2 phosphorylation contribute to the developmental excitatory-to-inhibitory GABA sequence.