Kinases SPAK and OSR1 are upregulated by estradiol and activate NKCC1 in the developing hypothalamus.
Kinases SPAK and OSR1 are upregulated by estradiol and activate NKCC1 in the developing hypothalamus.
复制标题
DOI：
10.1523/jneurosci.5415-11.2012
复制
发表时间：
2012-01-11
期刊：
影响因子：
--
通讯作者：
McCarthy MM
中科院分区：
文献类型：
--
作者：
Nugent BM;Valenzuela CV;Simons TJ;McCarthy MM
在未成熟神经元中，氨基酸类神经递质γ-氨基丁酸(GABA)通过GABA受体(GABA受体)引起膜去极化，从而为神经元的兴奋提供主要方式。对氯−的驱动力是外向的，因为Na+-K+-2Cl−共转运体(NKCC1)提高了这些细胞中氯−的浓度。GABA诱导的膜去极化和由此引起的电压门控钙通道的激活是大脑正常发育的基础，但调节GABA去极化的机制尚不清楚。神经类固醇雌二醇通过增强NKCC1共转运体的活性，有效地增强了未成熟下丘脑中GABA的去极化作用。了解雌激素是如何控制NKCC1活动的，对于全面了解大脑发育是至关重要的。我们现在报告，雌二醇治疗新生大鼠幼鼠显著增加NKCC1共转运蛋白上游的两个激酶Spak和OSR1的蛋白水平。雌激素诱导的NKCC1表达上调是转录依赖性的，其时程与雌激素促进NKCC1磷酸化的时程平行。反义寡核苷酸介导的Spak和较小程度的OSR1的敲除排除了雌二醇介导的NKCC1磷酸化的增强。在功能上，敲除胚胎下丘脑培养物中的Spak或OSR1可以减少由GABAAR激活引起的雌二醇促进的钙内流。我们的数据表明，SPAK和OSR1可能是调节发育中大脑中GABA介导的去极化过程的关键因素。在未来的研究中，研究这些激酶与性别差异和大脑发育异常的关系将是很重要的。
In immature neurons the amino acid neurotransmitter, γ-aminobutyric acid (GABA) provides the dominant mode for neuronal excitation by inducing membrane depolarization due to Cl− efflux through GABAA receptors (GABAARs). The driving force for Cl− is outward because the Na+-K+-2Cl− cotransporter (NKCC1) elevates the Cl− concentration in these cells. GABA-induced membrane depolarization and the resulting activation of voltage-gated Ca2+ channels is fundamental to normal brain development, yet the mechanisms that regulate depolarizing GABA are not well understood. The neurosteroid estradiol potently augments depolarizing GABA action in the immature hypothalamus by enhancing the activity of the NKCC1 cotransporter. Understanding how estradiol controls NKCC1 activity will be essential for a complete understanding of brain development. We now report that estradiol treatment of newborn rat pups significantly increases protein levels of two kinases upstream of the NKCC1 cotransporter, SPAK and OSR1. The estradiol-induced increase is transcription dependent, and its time course parallels that of estradiol-enhanced phosphorylation of NKCC1. Antisense oligonucleotide-mediated knockdown of SPAK, and to a lesser degree of OSR1, precludes estradiol-mediated enhancement of NKCC1 phosphorylation. Functionally, knockdown of SPAK or OSR1 in embryonic hypothalamic cultures diminishes estradiol-enhanced Ca2+ influx induced by GABAAR activation. Our data suggest that SPAK and OSR1 may be critical factors in the regulation of depolarizing GABA-mediated processes in the developing brain. It will be important to examine these kinases with respect to sex differences and developmental brain anomalies in future studies.