Regulation of human organic cation transporter hOCT2 by PKA, PI3K, and calmodulin-dependent kinases
Regulation of human organic cation transporter hOCT2 by PKA, PI3K, and calmodulin-dependent kinases
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DOI：
10.1152/ajprenal.00251.2002
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发表时间：
2003-02-01
影响因子：
4.2
通讯作者：
Schlatter, E
中科院分区：
文献类型：
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作者：
Çetinkaya, I;Ciarimboli, G;Schlatter, E
使用荧光OC 4-[4-（二甲氨基）苯乙烯基]-N-甲基吡啶鎓（ASP（+））对HEK-293细胞中表达的人有机阳离子（OC）转运蛋白2型（hOCT 2）的特性和调控进行了广泛表征。ASP（+）摄取是产电的，并被TPA（+）（EC（50）= 2.7 μ M）、四乙基铵（EC（50）= 35 μ M）、西咪替丁（EC（50）= 36 μ M）或奎宁（EC（50）= 6.7 μ M）抑制。卡巴胆碱或ATP刺激分别使初始摄取减少44 +/- 3（n = 14）和34 +/- 4%（n = 21），独立于PKC，但依赖于磷脂酰肌醇3-激酶（PI 3 K）。PKA刺激使摄取减少18 +/- 4%（n = 40）。抑制钙调蛋白（CaM）、Ca（2+）/CaM依赖性激酶II或肌球蛋白轻链激酶分别使摄取减少63 +/- 2（n = 15）、40 +/- 4（n = 30）和31 +/- 4%（n = 16）。钙调素的抑制导致的EC（50）值的显着变化，抑制ASP（+）摄取四乙铵。总之，我们证明，hOCT 2被PI 3 K和PKA抑制，并被CaM依赖性信号通路激活，可能是通过改变底物亲和力。
Properties and regulation of the human organic cation (OC) transporter type 2 (hOCT2) expressed in HEK-293 cells were extensively characterized using the fluorescent OC 4-[4-(dimethylamino) styryl]-N-methylpyridinium (ASP(+)). ASP(+) uptake was electrogenic and inhibited by TPA(+) (EC(50) = 2.7 muM), tetraethylammonium (EC(50) = 35 muM), cimetidine (EC(50) = 36 muM), or quinine (EC(50) = 6.7 muM). Stimulation with carbachol or ATP decreased initial uptake by 44 +/- 3 (n = 14) and 34 +/- 4% (n = 21), respectively, independently of PKC but dependent on phosphatidylinositol 3-kinase (PI3K). PKA stimulation decreased uptake by 18 +/- 4% (n = 40). Inhibition of calmodulin (CaM), Ca(2+)/CaM-dependent kinase II, or myosin light chain kinase decreased uptake by 63 +/- 2 (n = 15), 40 +/- 4 (n = 30), and 31 +/- 4% (n = 16), respectively. Inhibition of CaM resulted in a significant change in the EC(50) value for the inhibition of ASP(+) uptake by tetraethylammonium. In conclusion, we demonstrate that the hOCT2 is inhibited by PI3K and PKA and activated by a CaM-dependent signaling pathway, probably via a change in substrate affinity.