Dual Functional Characteristic of Human Aquaporin 10 for Solute Transport
Dual Functional Characteristic of Human Aquaporin 10 for Solute Transport
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DOI：
10.1159/000330083
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发表时间：
2011-01-01
影响因子：
--
通讯作者：
Yuasa, Hiroaki
中科院分区：
文献类型：
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作者：
Ishii, Megumi;Ohta, Kinya;Yuasa, Hiroaki
背景/目的：虽然人们普遍认为水通道蛋白对甘油和水的作用是通道模式，具有不饱和性质，但我们最近发现，人类水通道蛋白9 （hAQP9）对甘油的作用是载体介导的模式，具有饱和性质。基于这一发现，我们假设这一特性可能与其他的水甘油oporin共享，并研究了hAQP10的功能特征，hAQP10是一种肠道特异性的水甘油oporin。方法：用表达hAQP10的非洲爪蟾卵母细胞进行转运实验。结果：hAQP10对甘油的转运具有高度饱和性，Michaelis常数为10.4 μ M，并被几种甘油类似物（如单乙酰素）特异性抑制。此外，当在表达haqp10的卵母细胞中预加载甘油时，其外排受到细胞外甘油的反式刺激。这些结果表明hAQP10参与了载体介导的甘油运输机制。有趣的是，一个通道机制也被发现部分参与haqp10介导的甘油运输。结论：本研究揭示了hAQP10作为溶质转运载体/通道的独特双重功能特征，为其运作机制提供了新的认识，有助于进一步阐明其生理作用。巴塞尔S. Karger股份有限公司版权所有
Background/Aims: Although aquaglyceroporins have been generally believed to operate in a channel mode, which is of nonsaturable nature, for glycerol as well as for water, we recently found that human aquaporin 9 (hAQP9) operates in a carrier-mediated mode, which is of saturable nature, for glycerol. Based on the finding, we assumed that such a characteristic might be shared by the other aquaglyceroporins and examined the functional characteristics of hAQP10, which is an intestine-specific aquaglyceroporin. Methods: Transport assays were conducted using Xenopus laevis oocytes expressing hAQP10 derived from the microinjected cRNA. Results: The transport of glycerol by hAQP10 was found to be highly saturable with a Michaelis constant of 10.4 mu M and specifically inhibited by several glycerol analogs such as monoacetin. Furthermore, when glycerol was preloaded in hAQP10-expressing oocytes, its efflux was trans-stimulated by extracellular glycerol. These results indicate the involvement of a carrier-mediated mechanism in glycerol transport by hAQP10. Interestingly, a channel mechanism was also found to be involved in part in hAQP10-mediated glycerol transport. Conclusion: The present study unveiled the uniquely dual functional characteristic of hAQP10 as a carrier/channel for solute transport, providing a novel insight into its operation mechanism, which would help further elucidate its physiological role. Copyright (C) 2011 S. Karger AG, Basel