Functional expression of TASK-1/TASK-3 heteromers in cerebellar granule cells
Functional expression of TASK-1/TASK-3 heteromers in cerebellar granule cells
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DOI：
10.1113/jphysiol.2003.054387
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发表时间：
2004-01-01
影响因子：
5.5
通讯作者：
Kim, DH
中科院分区：
文献类型：
--
作者：
Kang, DW;Han, JH;Kim, DH
ASK-1和ASK-3是串联孔K+（K-2 P）通道家族的功能成员，并且两个通道的mRNA在许多脑区域中一起表达。尽管当它们的互补RNA被注射到卵母细胞中时，ASK-1和ASK-3亚基能够形成异聚体，但功能性异聚体是否存在于天然组织中尚不清楚。使用培养的小脑颗粒（CG）神经元表达的mRNA的任务-1和任务-3，我们研究了存在的异聚体通过比较克隆和天然K+通道的敏感性细胞外pH值（pH（o））和钌红。在COS-7细胞中表达的ASK-1、ASK-3和串联构建体（ASK-1/ASK-3）的单通道电导分别为14.2 +/-0.4、37.8 +/- 0.7和38.1 +/- 0.7 pS（-60 mV）。ASK-3和ASK-1/ASK-3（和ASK-3/ASK-1）显示出几乎相同的单通道动力学。当pH值从8.3变为7.3时，COS-7细胞中表达的ASK-3和ASK-1/ASK-3分别被抑制26 +/- 4和36 +/-2%。在CG神经元的外向斑片中，具有与ASK-3类似的单通道特性的K+通道被相同的pH（o）降低抑制了31 +/- 7%。任务3，。当将5 μ m钌红应用于外向贴片时，COS-7细胞中表达的ASK-1/ASK-3分别被抑制78 +/- 7和3 +/-4%。在从CG神经元含有一个38 pS通道的外向补丁，钌红两种类型的反应进行了观察。钌红在42%的贴片中抑制77 +/- 5%的通道活性（范围：72-82%），在58%的贴片中抑制5 +/- 4%（范围：0-9%）。当贴片含有三个以上的38 pS通道时，对钌红的平均响应为47 +/- 6%抑制（n = 5）。这些电生理学研究表明，培养的CG神经元中的天然38 pS K+通道的ASK家族由同聚体的ASK-3和异聚体的ASK-1/ASK-3。
TASK-1 and TASK-3 are functional members of the tandem-pore K+ (K-2P) channel family, and mRNAs for both channels are expressed together in many brain regions. Although TASK-1 and TASK-3 subunits are able to form heteromers when their complementary RNAs are injected into oocytes, whether functional heteromers are present in the native tissue is not known. Using cultured cerebellar granule (CG) neurones that express mRNAs of both TASK-1 and TASK-3, we studied the presence of heteromers by comparing the sensitivities of cloned and native K+ channels to extracellular pH (pH(o)) and ruthenium red. The single-channel conductance of TASK-1, TASK-3 and a tandem construct (TASK-1/TASK-3) expressed in COS-7 cells were 14.2 +/- 0.4,37.8 +/- 0.7 and 38.1 +/- 0.7 pS (-60 mV), respectively. TASK-3 and TASK-1/TASK-3 (and TASK-3/TASK-1) displayed nearly identical single-channel kinetics. TASK-3 and TASK-1/ TASK-3 expressed in COS-7 cells were inhibited by 26 +/- 4 and 36 +/- 2%, respectively, when pH. was changed from 8.3 to 7.3. In outside-out patches from CG neurones, the K+ channel with single channel properties similar to those of TASK-3 was inhibited by 31 +/- 7% by the same reduction in pH(o). TASK-3 and. TASK-1/TASK-3 expressed in COS-7 cells were inhibited by 78 +/- 7 and 3 +/- 4%, respectively, when 5 mum ruthenium red was applied to outside-out patches. In outside-out patches from CG neurones containing a 38 pS channel, two types of responses to ruthenium red were observed. Ruthenium red inhibited the channel activity by 77 +/- 5% in 42% of patches (range: 72-82%) and by 5 +/- 4% (range: 0-9%) in 58% of patches. When patches contained more than three 38 pS channels, the average response to ruthenium red was 47 +/- 6% inhibition (n = 5). These electrophysiological studies show that native 38 pS K+ channels of the TASK family in cultured CG neurones consist of both homomeric TASK-3 and heteromeric TASK-1/TASK-3.