Molecular physiology and pharmacology of TRESK K2P K+ channels

TRESK钾离子通道属于多方面的双孔结构域钾（K2 P）通道家族，是细胞兴奋性的重要调节剂，其参与从激素分泌和化学感受到麻醉、神经保护和疼痛的许多生理和病理生理过程。TRESK通道在背根神经节以及三叉神经节神经元中高度表达，并参与疼痛感觉，例如偏头痛，构成有希望的药理学靶标。TRESK电流通过钙调磷酸酶和几种磷酸激酶（例如MAPK、PKA和PKC）（靶向TRESK通道特有的大胞质结构域）的磷酸化（去）而受到强烈调节。此外，重要的细胞脂质，包括DAG，花生四烯酸，花生四烯酸和2-AG被发现抑制TRESK活性，但其生理相关性是未探索的。此外，许多小的药物分子通过知之甚少的机制抑制该通道。最后，TRESK通道最近已显示与TREK-1和TREK-2形成异聚体，并且这些异聚体涉及某些偏头痛病症。因此，尽管其在疼痛病症的治疗中有希望的意义，但该通道的特征仍然很差，并且TRESK功能在机制上没有被理解。在这里，我们建议应用系统扫描诱变、半胱氨酸修饰、同源性建模和膜片钳电生理学来（1）鉴定小分子和脂质结合位点，（2）深入了解由例如磷酸化调节的内在TRESK门的性质，和（3）探索通过释放脂质信使影响TRESK通道的受体途径和（4）表征TREK/TRESK异源聚体与这里收集的关于同源TRESK通道的知识。因此，该项目旨在促进对TRESK通道的分子生理学和药理学知之甚少的机制洞察。

The TRESK potassium ion channel belongs to the multifaceted Two-Pore-Domain Potassium (K2P) channel family, important regulators of cellular excitability, which participate in many physiological and pathophysiological processes from hormone secretion and chemosensation to anaesthesia, neuroprotection and pain. TRESK channels are highly expressed in dorsal root ganglia as well as trigeminal ganglia neurons and involved in pain sensation such as migraine constituting promising pharmacological targets. TRESK currents are strongly regulated by (de)phosphorylation via Calcineurin and several Phosphokinases (e.g. MAPK, PKA and PKC) that target a large cytoplasmic domain unique to the TRESK channel. Furthermore, important cellular lipids including DAG, arachidonic acid, anandamide and 2-AG were found to inhibit TRESK activity but its physiological relevance is unexplored. In addition, many small drug molecules inhibit this channel by a poorly understood mechanism. Finally, TRESK channels have been recently shown to form heteromers with TREK-1 and TREK-2 and these heteromers are involved in certain conditions of migraine. Thus, despite its promising implication in the treatment of pain conditions, the channel is still poorly characterized and TRESK function is not understood mechanistically. Here we propose to apply systematic scanning mutagenesis, cysteine modification, homology modeling and patch-clamp electrophysiology to (1) identify the small molecule and lipid binding sites, (2) gain insight into the nature of the intrinsic TRESK gate regulated by e.g. phosphorylation, and (3) explore the receptor pathways that affect TRESK channels via the release of lipid messengers and (4) characterize TREK/TRESK heteromers with respect to the knowledge gathered here on homomeric TRESK channels. This project therefore aims to promote mechanistic insight into the poorly understood molecular physiology and pharmacology of TRESK channels.