Pannexin-1 channels as facilitators of anandamide membrane transport

Pannexin-1 通道作为 anandamide 膜转运的促进剂

• 批准号: RGPIN-2018-04775
• 负责人: Thompson, Roger
• 金额: $ 3.64万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713213
• 关键词: Pannexin; channels; facilitators; anandamide; membrane

The regulated movement of ions and small signaling molecules across the plasma membrane occurring through facilitated transport (channels and transporters) is a fundamental basis of cellular physiology. The close regulation of Ca2+ influx, for example, can determine the difference between normal and detrimental signaling. For several decades, my research program has been investigating mechanisms of facilitated transport and we having made several seminal discoveries. As an NSERC funded postdoc, I challenged the concept that ATP transport into the Golgi complex was mediated by a classical transporter. Rather I showed it was an ATP permeable anion channel. Since starting my own lab (in 2008), our research program has discovered that the ionotropic receptor for glutamate, the N-Methyl-D-Aspartate receptor (NMDAR) has a metabotropic signaling role in addition to its canonical ionotropic function. Thus, we continue to question the concept that channels are only channels, transporters are only transporters and that there is a clear distinction between ionotropic and metabotropic receptors. This Discovery grant proposal is focused on understanding the biophysics and neurophysiology of a novel facilitated transport role of the pannexin-1 (Panx1) channel. Panx1 is a non-selective ion and metabolite channel belonging to the gap junction superfamily. Importantly, it does not form intracellular gap junctions, rather it functions in plasma membranes as a bona fide channel, joining the intra- and extracellular spaces. Panx1 is best characterized as an ATP permeable channel that contributes to, and is regulated by, purinergic signaling pathways. Our previous NSERC grant focused on understanding the roles of Panx1 in purinergic signaling and immune responses. During this funding period we had several critical insights that have shaped the present proposal. For example, the mechanisms that regulate the opening of Panx1 channels are poorly characterized. Our understanding of the scope of the types of ions and molecules that can permeate the channels is limited, which restricts characterization of the likely diverse physiological roles of Panx1. In this regard, we made the important discovery that Panx1 can facilitate the transport of the signaling lipid, N-arachidonoylethanolamine (andandamide; AEA), a critical ligand in the endocannabinoid system. This Discovery grant will test the general hypothesis that Panx1 facilitates the transport of AEA to regulate endocannabinoid signaling in the brain. Our approach is unique and innovative, providing exciting opportunities for the training and development of highly qualified personnel. The work here will dramatically increase our understanding of the diverse biological roles of Panx1 through identifying a new and unique transport mechanism for anandamide and determining how this modulates neuronal function and circuit output.

通过易化转运（通道和转运蛋白）发生的离子和小信号分子跨质膜的调节运动是细胞生理学的基本基础。 例如，Ca 2+内流的密切调节可以决定正常和有害信号之间的差异。几十年来，我的研究项目一直在研究促进运输的机制，我们已经取得了一些开创性的发现。 作为NSERC资助的博士后，我挑战了ATP转运到高尔基复合体是由经典转运蛋白介导的概念。相反，我展示了它是一个ATP渗透性阴离子通道。自从我自己的实验室成立以来（2008年），我们的研究计划发现谷氨酸的离子型受体，N-甲基-D-天冬氨酸受体（NMDAR）除了其典型的离子型功能外，还具有代谢信号作用。 因此，我们继续质疑这样的概念，即通道只是通道，转运蛋白只是转运蛋白，离子型和代谢型受体之间有明显的区别。 这项发现资助计划的重点是了解泛连接蛋白-1（Panx 1）通道的新型易化转运作用的生物物理学和神经生理学。 Panx 1是属于差距连接超家族的非选择性离子和代谢物通道。重要的是，它不形成细胞内间隙连接，而是在质膜中作为真正的通道发挥作用，连接细胞内和细胞外空间。Panx 1最好的特点是作为一个ATP渗透通道，有助于，并受嘌呤信号通路。 我们之前的NSERC资助专注于了解Panx 1在嘌呤能信号传导和免疫反应中的作用。 在这一供资期间，我们有几个重要的见解，形成了目前的建议。例如，调节Panx 1通道开放的机制的特征很差。 我们对可以渗透通道的离子和分子类型的范围的理解是有限的，这限制了Panx 1可能的多种生理作用的表征。 在这方面，我们做出了重要的发现，Panx 1可以促进信号脂质N-花生四烯酸乙醇胺（andandamide; AEA）的转运，这是内源性大麻素系统中的关键配体。 这项发现资助将测试Panx 1促进AEA的运输以调节大脑中内源性大麻素信号的一般假设。 我们的方法是独特和创新的，为高素质人才的培训和发展提供了令人兴奋的机会。 这项工作将通过确定anandamide的一种新的独特的转运机制，并确定它如何调节神经元功能和电路输出，大大增加我们对Panx 1的多种生物学作用的理解。