Molecular architecture of claudin-based tight junction strands and paracellular ion channels

基于紧密连接蛋白的紧密连接链和细胞旁离子通道的分子结构

• 批准号: 289412825
• 负责人: Privatdozent Dr. Jörg Piontek
• 金额: --
• 依托单位: Medizinische Klinik für Gastroenterologie, Infektiologie und Rheumatologie (CBF)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/289412825?language=en
• 关键词: Molecular; architecture; claudin; based; tight

Tight junctions (TJ) regulate the paracellular permeability for solutes and water across epithelial and endothelial tissue barriers. The key structural determinants for this function are the tetra-helical transmembrane proteins of the claudin (CLDN) family. They form the backbone of intramembrane TJ strands and depending on the subtype either barriers or paracellular channels for small cations, anions or water. Progress in crystallization, structure prediction, MD simulations and functional analysis of claudins strongly advanced the understanding of TJ structure and function. However, the molecular architecture of TJ strands and paracellular channels is still under debate. Although claudin sequence determinants influencing assembly and function have been identified, the 3D-structural differences leading to the functional diversity of TJs (channels for cation, cation & water or anions or ion barriers) are unclear. Main goal of the project is to elucidate the detailed molecular architecture of TJ strands and paracellular channels including claudin subtype-dependent diversity. Previously, we established and successfully applied methods (a) to dissect the multistep process of TJ strand assembly that includes homo- and heterophilic, cis- and trans-interactions between claudins (b) to investigate the transport physiology of TJs and (c) to model and simulate the molecular dynamics of claudin oligomers in a membrane environment. Crucially for the TJ field, convergence of cell-physiological, nanoscopic and structural/simulation data on TJ strands is still largely missing. The general aim of this funding period is to achieve this convergence for claudins expressed in the gastrointestinal tract and/or the kidney. The specific aims are elucidation of the structural and mechanistic basis for (i) selectivity of CLDN10b/CLDN15-like cation channels and that of CLDN10a- and CLDN17 anion channels, (ii) barrier (CLDN1, -3, -5) versus channel formation, (iii) claudin intermixing and segregation into functionally distinct segments along TJ strands and (iv) disturbance of channel or barrier function of claudins by pathogenic mutations. The proposal bundles cell-physiological and structural bioinformatics expertises on classic claudins. Since TJ function is essential for all organs and disturbed in a multitude of barrier- and transport-related diseases affecting the intestine, kidney, glands or the brain, the project will provide key insights in the molecular physiology and pathophysiology of tissues barriers in general.

紧密连接（TJ）调节溶质和水穿过上皮和内皮组织屏障的细胞旁渗透性。这种功能的关键结构决定因素是紧密连接蛋白（CLDN）家族的四螺旋跨膜蛋白。它们形成膜内TJ链的骨架，并取决于小阳离子、阴离子或水的屏障或细胞旁通道的亚型。claudins的结晶、结构预测、分子动力学模拟和功能分析等方面的进展极大地促进了对TJ结构和功能的理解。然而，TJ链和细胞旁通道的分子结构仍在争论中。虽然已经确定了影响组装和功能的claudin序列决定因素，但导致TJ功能多样性的3D结构差异（阳离子通道，阳离子和水或阴离子或离子屏障）尚不清楚。该项目的主要目标是阐明TJ链和细胞旁通道的详细分子结构，包括claudin亚型依赖的多样性。以前，我们建立并成功地应用了方法（a）解剖TJ链组装的多步骤过程，包括同源和异源，cis-和trans-interactions之间的封闭蛋白（B），研究运输生理学的TJ和（c）建模和模拟封闭蛋白寡聚体在膜环境中的分子动力学。对于TJ领域至关重要的是，TJ链上的细胞生理学、纳米级和结构/模拟数据的收敛在很大程度上仍然缺失。本资助期的总体目标是实现胃肠道和/或肾脏中表达的claudins的这种趋同。具体目的是阐明（i）CLDN 10 b/CLDN 15样阳离子通道的选择性以及CLDN 10 a和CLDN 17阴离子通道的选择性，（ii）屏障通道的结构和机制基础。（CLDN 1，-3，-5）与通道形成，（iii）密蛋白沿着TJ链混合和分离成功能不同的片段，和（iv）致病性突变引起的封闭蛋白通道或屏障功能紊乱。该提案将细胞生理学和结构生物信息学的专业知识结合在经典的claudins上。由于TJ功能对所有器官都是必不可少的，并且在影响肠道，肾脏，腺体或大脑的多种屏障和运输相关疾病中受到干扰，该项目将为组织屏障的分子生理学和病理生理学提供关键见解。