Study of the permeability of cellular membranes using proteoliposomes

渗透性是指化合物通过生物屏障，如皮肤、肺上皮或胃肠道。除了这些外部障碍外，还存在内部障碍，限制了化合物在血液、中枢神经系统和器官等身体不同部分之间的转移。这些屏障是生物体抵御化学威胁的天然屏障，但同时它们也不能完全不渗透，因为营养、呼吸和排泄是基本的生理功能。渗透性在营养、药物吸收和分配以及毒理学等多个科学领域都有影响。 在细胞水平上，化合物的渗透性受两种机制的调节。第一种机制是化合物在细胞膜中的被动扩散。这一机制取决于化合物的物理化学性质。利用简单的人工膜可以很容易地研究被动扩散。第二种机制称为主动传输。膜运输蛋白可以从膜的一侧提取特定的化合物，并将它们携带到另一侧。要在实验室中研究这一过程，通常需要细胞模型或活细胞。事实上，主动运输需要部分细胞机械才能工作。简单的人造膜不能模拟主动运输。 我们建议使用新型人工囊泡，即蛋白质脂质体来研究主动扩散和被动扩散。蛋白脂质体是一种人造的非细胞囊泡，类似于活细胞。特定的蛋白质可以包含在它们的膜上，以实现主动运输。这类工具将有助于使用非细胞模型研究渗透性，包括主动传输和被动扩散。 这项研究的挑战包括在保持膜转运蛋白活性的同时提取和纯化膜转运蛋白，以及设计功能蛋白脂质体文库。这些挑战存在于自然科学和工程领域。在这项应用覆盖的五年后，在转运膜蛋白和蛋白脂质体方面获得的知识可以转化为额外的项目，如集成微流控设备的概念，甚至设计多药耐药癌症的非细胞模型。

Permeability is the passage of a chemical compound through a biological barrier such as the skin, the pulmonary epithelium or the gastrointestinal tract. In addition to these external barriers, internal barriers also exist limiting the transfer of compounds between the different compartments of the body like the blood, the central nervous system and the organs. These barriers are the natural defenses of the organism against chemical threats, but at the same time they cannot be completely impermeable as nutrition, breathing and excretion are essential physiological functions. Permeability has a impact in multiple fields of science like nutrition, drug absorption and distribution as well as toxicology. At the cellular level, permeability of a compound is regulated by two mechanisms. The first mechanism is passive diffusion of the compound through the cellular membrane. This mechanism depends on the physicochemical properties of the compound. It is easy to study passive diffusion using simple artificial membranes. The second mechanism is named active transport. Membrane transport proteins can extract specific compounds from one side of the membrane and carry them to the other side. To study this process in the laboratory, cellular models or living cells are typically required. Indeed, active transport requires part of the cellular machinery to work. Simple artificial membranes cannot model active transport. We propose to study active and passive diffusion using novel artificial vesicles, namely proteoliposomes. Proteoliposomes are artificial and non-cellular vesicles resembling living cells. Specific proteins can be included in their membrane to enable active transport. Such tools will facilitate the study of permeability including active transport and passive diffusion using non-cellular models. The challenges of this research includes the extraction and purification of membrane transport proteins while maintaining their activity as well as the design of a library functional proteoliposomes. These challenges lie in the field of natural science and engineering. After the five years covered by this application, the knowledge achieved on transport membrane proteins and proteoliposomes could be translated into additional projects such as the conception of integrated microfluidic devices or even the design of non-cellular models of multidrug resistant cancers.