Coupling of organic anion transport to the glutamate gradient by OATs and OATPs

OAT 和 OATP 耦合有机阴离子转运至谷氨酸梯度

• 批准号: BB/L020823/1
• 负责人: Rohan Lewis
• 金额: $ 44.63万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL020823%2F1
• 关键词: Coupling; organic; anion; transport; glutamate

The organic anion transporter (OAT) and functionally related organic anion transporting peptide (OATP) families transport a wide range of biologically and pharmacologically important molecules into and out of cells. They transport hormones, metabolites, waste products and many drugs including aspirin, antibiotics, anticancer, cholesterol and blood pressure lowering drugs. They mediate the intestinal absorption of drugs into the body, the transport these drugs into target cells and finally the removal of these drugs from the body via the kidneys and liver. For example, the reason that some medications cannot be taken with grapefruit juice is that it inhibits specific OATPs. This project will investigate how these transporters obtain the energy they require from chemical gradients to undertake their essential biological and pharmacological roles.OAT and OATPs can transport substances both into and out of cells. If you want to pump a drug into a cell, transporting in both directions is inefficient (as what comes in can go straight out again). However, by coupling transporter activity to a second substrate it is possible to mediate transfer of the drug in one direction (as the substance of interest is taken up but cannot get out again because the second substrate is using the transporter). For this to work the second substrate must have a higher concentration within the cell than the substance in question. Glutamate concentrations within the cell are 50-100 x higher than in plasma and we have found that OAT4 and OATP2B1 transport glutamate. Thus the glutamate gradient could drive uptake of drugs and other molecules transported by OAT4 and OATP2B1. In an analogous manner to the release of water stored behind a dam, when the glutamate is released from the cell the potential energy stored in the gradient can be captured and used to drive the uptake of drugs.There are multiple OAT and OATP transporters many of which transport the same molecules. If some of these transporters are coupled to the glutamate gradient, and some are not, then even though they transport the same substrates they will act in different ways and play different roles in the body. Those being coupled to the glutamate gradient (e.g. OAT4) would mediate uptake of drugs and hormones while those which are not would be more likely to mediate efflux. The first aim of this project will be to determine which other members of the OAT and OATP families transport glutamate. The fact that OAT4, OATP2B1 or any other OAT/OATP, transports glutamate does not necessarily mean that its activity will be coupled to the glutamate gradient; this will depend on the kinetics of glutamate transfer, the presence of other substrates and the subcellular localisation of glutamate. The second aim of this project will be to determine when a specific substrate is taken up, then what intracellular molecules is it exchanged for in human cells. It can become difficult to predict how a transporter will function if its activity depends on the concentrations of multiple different substrates on two sides of a biological membrane. It is even more complicated when there are different transporters for the same substrates in the same membrane or in apical and basal membranes of an epithelial barrier. The third aim of this project is to develop a physiologically based mathematical model of how these transporters work. This will allow us to predict how they will function together and how this will affect the transport of their endogenous substrates and of therapeutic agents. The OAT and OATP families play essential biological roles and are important for our understanding of normal cellular function and drug pharmacology. This project explores the extent to which glutamate, which has a large trans-membrane gradient compared to other OAT/OATP substrates, drives the activity of these transporters and provide mathematical models which will help us explain and predict their function throughout the body.

有机阴离子转运蛋白(OAT)和功能相关的有机阴离子转运肽(OATP)家族将多种重要的生物和药理重要分子转运进和出细胞。它们运输激素、代谢物、废物和许多药物，包括阿司匹林、抗生素、抗癌药物、胆固醇和降压药。它们调节肠道对药物的吸收进入体内，将这些药物输送到靶细胞，最后通过肾脏和肝脏将这些药物从体内清除。例如，一些药物不能与西柚汁一起服用的原因是它抑制了特定的OATP。这个项目将研究这些转运蛋白如何从化学梯度中获得所需的能量，以承担其基本的生物和药理作用。燕麦和燕麦转运蛋白可以将物质输送进和运出细胞。如果你想把一种药物注入细胞，双向运输效率很低(因为进来的东西可能会再次径直流出)。然而，通过将转运蛋白活性偶联到第二底物上，有可能在一个方向上调节药物的转移(因为目标物质被摄取，但由于第二底物正在使用转运蛋白而不能再次出来)。要做到这一点，第二种底物在细胞内的浓度必须高于所讨论的物质。细胞内的谷氨酸浓度是血浆中的50-100倍，我们发现OAT4和OATP2B1运输谷氨酸。因此，谷氨酸梯度可以促进药物和其他由OAT4和OATP2B1运输的分子的摄取。类似于水坝后面储存的水的释放，当谷氨酸从细胞中释放出来时，储存在梯度中的势能可以被捕获并用于驱动药物的吸收。有多个燕麦和OATP转运体，其中许多转运体运输相同的分子。如果这些转运蛋白中的一些与谷氨酸梯度偶联，另一些则不是，那么即使它们运输相同的底物，它们也会以不同的方式发挥作用，在体内发挥不同的作用。那些连接到谷氨酸梯度的物质(如燕麦片4)会调节药物和激素的吸收，而那些没有耦合到谷氨酸梯度的物质则更有可能调节外流。该项目的第一个目标将是确定OAT和OATP家族中哪些其他成员运输谷氨酸。事实是，OAT4、OATP2B1或任何其他OAT/OATP运输谷氨酸并不一定意味着其活性将与谷氨酸梯度耦合；这将取决于谷氨酸转移的动力学、其他底物的存在以及谷氨酸的亚细胞定位。该项目的第二个目标将是确定特定底物何时被吸收，然后在人类细胞中它被交换为什么细胞内分子。如果转运蛋白的活性取决于生物膜两侧多个不同底物的浓度，那么很难预测转运蛋白的功能。当相同底物的同一膜或上皮屏障的顶膜和基膜中有不同的转运体时，情况就更复杂了。这个项目的第三个目标是开发一个基于生理的数学模型来研究这些转运蛋白是如何工作的。这将使我们能够预测它们将如何共同发挥作用，以及这将如何影响其内源底物和治疗剂的运输。OAT和OATP家族发挥着重要的生物学作用，对我们理解正常的细胞功能和药物药理学具有重要意义。该项目探索谷氨酸在多大程度上驱动这些转运蛋白的活性，并提供数学模型来帮助我们解释和预测它们在体内的功能。与其他燕麦/OATP底物相比，谷氨酸具有较大的跨膜梯度。

项目成果

Glutamate cycling may drive organic anion transport on the basal membrane of human placental syncytiotrophoblast.

谷氨酸循环可能驱动有机阴离子在人胎盘合成细胞基底膜上的转运。

• DOI: 10.1113/jp270743
• 发表时间: 2015-10-15
• 期刊: The Journal of physiology
• 作者: Lofthouse EM;Brooks S;Cleal JK;Hanson MA;Poore KR;O'Kelly IM;Lewis RM
• 通讯作者: Lewis RM

A systems perspective on placental amino acid transport.

• DOI: 10.1113/jp274883
• 发表时间: 2018-12
• 期刊: The Journal of physiology
• 作者: Cleal JK;Lofthouse EM;Sengers BG;Lewis RM
• 通讯作者: Lewis RM

Estrone sulphate uptake by the microvillous membrane of placental syncytiotrophoblast is coupled to glutamate efflux.

• DOI: 10.1016/j.bbrc.2018.10.074
• 发表时间: 2018-11-17
• 期刊: Biochemical and biophysical research communications
• 影响因子: 3.1
• 作者: Lofthouse EM;Cleal JK;O'Kelly IM;Sengers BG;Lewis RM
• 通讯作者: Lewis RM

Modeling bispecific monoclonal antibody interaction with two cell membrane targets indicates the importance of surface diffusion.

• DOI: 10.1080/19420862.2016.1178437
• 发表时间: 2016-07
• 期刊: mAbs
• 影响因子: 5.3
• 作者: Sengers BG;McGinty S;Nouri FZ;Argungu M;Hawkins E;Hadji A;Weber A;Taylor A;Sepp A
• 通讯作者: Sepp A

N-acetylcysteine, xCT and suppression of Maxi-chloride channel activity in human placenta.

• DOI: 10.1016/j.placenta.2021.05.009
• 发表时间: 2021-06
• 期刊: Placenta
• 影响因子: 3.8
• 作者: E. Lofthouse;A. Manousopoulou;J. Cleal;I. O'kelly;K. Poore;S. Garbis;Rohan M. Lewis