On the temperature and tension dependence of the outer hair cell lateral membrane conductance GmetL and its relation to prestin.
On the temperature and tension dependence of the outer hair cell lateral membrane conductance GmetL and its relation to prestin.
复制标题
外毛细胞侧膜电导 GmetL 的温度和张力依赖性及其与 prestin 的关系。
DOI：
10.1007/s00424-005-0037-2
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Navaratnam,Dhasakumar
中科院分区：
文献类型：
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作者：
Santos-Sacchi,Joseph;Rybalchenko,Volodymyr;Bai,Jun-Ping;Song,Lei;Navaratnam,Dhasakumar
最近，我们发现了外毛细胞（OHC）外侧膜电导GmetL，它与prestin共定位并传递Cl−，从而影响prestin （SLC26A5）的机电活性。在这项研究中，我们报告了gmetland prestin的温度和张力依赖性的比较。虽然我们发现每个温度和张力都有显著的依赖性，但存在实质性的差异，表明它们的独立身份。以下数据支持这一结论：(1)当prestin的非线性电容（NLC）函数被温度或膜张力移位时，gmetl的电压依赖性不遵循prestin的非线性电容（NLC）函数；(2)与天然OHCs的NLC可被细胞外Cl−内流调节不同，预抑素转染的中国仓鼠卵巢（CHO）细胞没有表现出这种现象；(3)在CHO细胞中转染prestin后，未发现拉伸敏感的单通道电流；(4) prestin表达水平（通过NLC测量）与通过gmetl的跨膜电流之间没有相关性。因此，gmetl一定是由OHC侧膜内另一种分子的活性产生的。其特性的一个线索是电导的非线性温度依赖性，而不是prestin和其他热液电导的线性依赖性。热盐中K+电导呈现均匀的q10，接近1.2，而gmetl呈现双峰q10，在34℃以下aq10为1.5，aq10大于4及以上。SLC26A5 （prestin）和gmetl的解离在理论上通过OHC侧膜内这些相互作用伙伴之间的空间分离程度提供了可修改的阴离子反馈给prestin。
Recently, we identified an outer hair cell (OHC) lateral membrane conductance,GmetL, that colocalizes with prestin and passes Cl−, thereby influencing prestin’s (SLC26A5) electromechanical activity. In this study, we report on a comparison of the temperature and tension dependence ofGmetLand prestin. Though we find significant temperature and tension dependence of each, substantial differences exist which indicate their independent identity. The following data support this conclusion: (1) The voltage dependence ofGmetLdoes not follow that of prestin’s nonlinear capacitance (NLC) function when the latter is shifted by either temperature or membrane tension; (2) Unlike native OHCs whose NLC can be modulated by influx of extracellular Cl−, prestin-transfected Chinese hamster ovary (CHO) cells do not show this phenomenon; (3) Stretch-sensitive, single channel currents are not evidenced after prestin transfection in CHO cells; and (4) There is no correlation between prestin expression level (gauged via NLC) and transmembrane current throughGmetL. Thus,GmetLmust result from the activity of another molecular species within the lateral membrane of the OHC. A clue to its identity is the conductance’s nonlinear temperature dependence in contrast to prestin and other OHC conductances’ linear dependence. Whereas K+conductances in OHCs present a uniformQ10close to 1.2,GmetLshows a bimodalQ10, with aQ10of 1.5 below 34°C and aQ10of greater than 4 and above. The dissociation of SLC26A5 (prestin) andGmetLtheoretically provides for a modifiable anionic feedback to prestin via the degree of spatial separation between these interacting partners within the OHC lateral membrane.