Cholesterol modifies the gating of Kv1.3 in human T lymphocytes
Cholesterol modifies the gating of Kv1.3 in human T lymphocytes
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DOI：
10.1007/s00424-002-0974-y
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发表时间：
2003-03-01
影响因子：
4.5
通讯作者：
Gaspar, R
中科院分区：
文献类型：
--
作者：
Hajdú, P;Varga, Z;Gaspar, R
Kv1.3钾通道属于电压门控性K+通道的Shaker家族，在T细胞的促有丝分裂反应中起着至关重要的作用。由于它跨越细胞膜，其功能可能受到脂质-蛋白质相互作用的影响。为了研究脂质-蛋白质相互作用对Kv1.3功能的影响，我们通过寡糖甲基-β-环糊精（MbetaCD）及其胆固醇饱和复合物（MbetaCD/C）模拟各种生理条件操纵T细胞中的膜胆固醇含量。荧光偏振各向异性和峰值电流密度用于监测胆固醇去除效率（MbetaCD）和负载效率（MbetaCD/C）。采用全细胞膜片钳技术，我们测定了不同处理条件下Kv1.3电流激活和失活的动力学和稳态参数。当胆固醇含量升高1或1.5 mg/ml MbetaCD/C时，激活和失活速率均减慢。此外，膜中胆固醇水平的增加导致双相活化曲线。MbetaCD（0.95和1.425 mg/ml）的胆固醇消耗未导致Kv1.3的门控特征发生显著变化。通道的开放和闭合状态之间的平衡受到胆固醇含量增加的影响，但同时稳态失活不变。我们认为，操纵膜胆固醇改变了动力学特性的Kv1.3和稳态参数的激活通过修改脂质-蛋白质相互作用。
The Kv1.3 potassium channel that belongs to the Shaker family of voltage-gated K+ channels plays a crucial role in the mitogenic response of T cells. Because it spans the cell membrane its function can be influenced by lipid-protein interactions. In order to study the effect of lipid-protein interactions on the functioning of Kv1.3 we manipulated the membrane cholesterol content in T cells mimicking various physiological conditions by means of the oligosaccharide methyl-p-cyclodextrin (MbetaCD) and its cholesterol-saturated complex (MbetaCD/C). Fluorescence polarization anisotropy and peak current density were used to monitor the efficiency of cholesterol removal (MbetaCD) and loading (MbetaCD/C). Using whole-cell patch-clamp technique we determined the kinetic and steady-state parameters of activation and inactivation of the Kv1.3 currents under different treatment conditions. Upon elevation of cholesterol content by 1 or 1.5 mg/ml MbetaCD/C the rates of both activation and inactivation were slowed. Moreover, the increased cholesterol level in the membrane resulted in a biphasic activation curve. Cholesterol depletion with MbetaCD (0.95 and 1.425 mg/ml) caused no significant changes in the gating characteristics of Kv1.3. The equilibrium between the open and the closed states of the channels was affected by increased cholesterol content, but at the same time steady-state inactivation was unchanged. We argue that manipulation of membrane cholesterol changed both the kinetic properties of Kv1.3 and steady-state parameters of activation by modifying lipid-protein interactions.