Kinetic properties of human AMPA-type glutamate receptors expressed in HEK293 cells
Kinetic properties of human AMPA-type glutamate receptors expressed in HEK293 cells
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DOI：
10.1046/j.1460-9568.2003.02531.x
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发表时间：
2003-03-01
影响因子：
3.4
通讯作者：
Bufler, J
中科院分区：
文献类型：
--
作者：
Grosskreutz, J;Zoerner, A;Bufler, J
AMPA型谷氨酸受体（AMPAR）的功能特性具有高度的可变性，决定了兴奋性突触后电位的时程。它们被组装为不同剪接变体和核编辑同种型的GluR亚基1-4的四聚体。目前，用膜片钳技术和超快激动剂应用研究了HEK 293细胞中瞬时表达的人AMPAR（分别为R和G编辑形式的GluR 1、3和4翻转和翻转，以及GluR 2翻转和翻转）的激活、脱敏和从脱敏恢复的动力学。所有受体的激活时间常数相同（0.13 ms）。GluR 2翻转G变体表现出最慢的脱敏（10.8 ms），GluR 4翻转最快（1.6 ms）。脱敏的恢复时间在3.1 ms（GluR 4翻转）和178 ms（GluR 1翻转）之间变化。为了确定异聚体受体中亚基之间的功能相互作用，共表达了GluR 1翻转和GluR 2翻转R。脱敏的时间常数随GluR 2 flip R cDNA转染量的增加而线性增加，从2.5 ms（GluR 1 flip homomers）增加到6.8 ms（GluR 2 flip R homomers）。恢复遵循单指数的时间过程，并在GluR 1翻转同源表达的时间常数为178毫秒。在所有GluR 1翻转/GluR 2翻转异聚体和GluR 2翻转R同聚体中，脱敏恢复的时间常数约为50 ms。这两个参数可能影响AMPA受体介导神经退行性疾病中谷氨酸诱导的慢性兴奋性毒性的能力。
AMPA-type glutamate receptors (AMPAR) display a high variability in functional properties, which determine the time course of excitatory postsynaptic potentials. They are assembled as tetramers of GluR subunits 1-4 of different splice variants and nuclear edited isoforms. Presently, the kinetics of activation, desensitization and recovery from desensitization of human AMPARs (GluR1, 3 and 4 flip and flop, and GluR2 flip and flop in R and G edited forms, respectively) transiently expressed in HEK293 cells were studied with patch-clamp techniques and ultra fast agonist application. Activation time constants were identical for all receptors (0.13 ms). The GluR2 flip G variant showed the slowest desensitization (10.8 ms), GluR4 flip the fastest (1.6 ms). Recovery from desensitization varied between 3.1 ms (GluR4 flip) and 178 ms (GluR1 flip). To determine functional interactions between subunits in heteromeric receptors the GluR1 flip and the GluR2 flip R were coexpressed. The time constant of desensitization increased linearly from 2.5 ms (GluR1 flip homomers) to 6.8 ms (GluR2 flip R homomers) with the amount of GluR2 flip R cDNA transfected. Recovery followed a monoexponential time course and had a time constant of 178 ms in GluR1 flip homomeric expression. In all GluR1 flip/GluR2 flip heteromers and in GluR2 flip R homomers desensitization recovered with a time constant of approximate to50 ms. Thus, subunit interaction seems likely during recovery but not desensitization. Both parameters might influence the ability of AMPA receptors to mediate glutamate induced chronic excitotoxicity in neurodegenerative diseases.