Structure and function of inositol triphosphate receptors

肌醇三磷酸受体的结构和功能

• 批准号: 10645116
• 负责人: ERKAN KARAKAS
• 金额: $ 32.78万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-10 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10645116
• 关键词: Affinity; Agonist; Apoptosis; Architecture; Autoimmune Diseases; Binding; Binding Sites; Biochemical; Biological Assay; Biophysics; Calcium; Calcium Signaling; Cell division; Coupled; Cryoelectron Microscopy; Cytoplasm; Data; Development; Disease; Distant; Electrophysiology (science); Endoplasmic Reticulum; Fluorescence; Gene Expression; Goals; Growth Factor; Hormones; Human; ITPR1 gene; Image; Inositol; Ion Channel Gating; Learning; Ligands; Liposomes; Malignant Neoplasms; Mediating; Membrane; Memory; Metabolic; Metabolic Diseases; Mitochondria; Molecular; Molecular Conformation; Neurodegenerative Disorders; Neurotransmitters; Pathogenesis; Pathologic; Peptides; Physiological; Physiological Processes; Positioning Attribute; Property; Publishing; Receptor Inhibition; Regulation; Research; Resolution; Role; Signal Transduction; Site; Structure; Synaptic Transmission; Testing; Therapeutic Agents; X-Ray Crystallography; cell motility; cell type; desensitization; insight; mutant; novel; novel therapeutic intervention; novel therapeutics; patch clamp; pharmacologic; positive allosteric modulator; programs; protein aminoacid sequence; receptor; release of sequestered calcium ion into cytoplasm; small molecule; structural determinants; tool; trafficking; tripolyphosphate

PROJECT SUMMARY Inositol 1,4,5-triphosphate receptors (IP3Rs) integrate diverse signals generated by hormones, growth factors, neurotransmitters, and changes in metabolic state to modulate downstream signaling in all cell types. IP3Rs are ligand-gated ion channels that are further regulated by allosteric and covalent mechanisms, mediating Ca2+ release from the endoplasmic reticulum (ER). The resulting increases of cytoplasmic and mitochondrial Ca2+ concentrations regulate many physiological processes (e.g., learning, memory, membrane trafficking, synaptic transmission, secretion, motility, membrane excitability, gene expression, cell division, and apoptosis). Furthermore, pathological dysregulation of IP3Rs and calcium signaling is implicated in cancer, neurodegenerative, autoimmune, and metabolic diseases, making IP3Rs promising targets for treatment of these diseases. Despite recent advances in structural studies, fundamental questions regarding the mechanisms of ligand interactions and channel gating remain mostly unanswered, in part because of the large size and complexity of IP3Rs and the limited availability of specific pharmacological tools. In this proposal, we will (Aim 1) combine cryo-electron microscopy (cryo-EM) and X-ray crystallography in conjunction with functional IP3R assays based on fluorescence-based calcium imaging to elucidate the general themes of IP3R gating cycle and molecular basis for receptor inhibition by small molecules. Our recently published data revealed that the IP3 binding site is occupied by a loop that we have termed the self-binding peptide (SBP), which is located distantly in the primary sequence. We hypothesize that the SBP is a novel regulatory site in IP3Rs that can modulate the apparent affinity for IP3, and thereby Ca2+ channel activity, and that the divergence of SBP sequences between IP3R subtypes contributes to their distinct regulatory properties. We will perform (Aim 2) functional and structural studies on IP3R subtypes and SBP mutants to test this hypothesis and identify the structural determinants of this interaction. Completion of these aims will yield unparalleled mechanistic insight into IP3R gating and regulation, potentially leading to the development of novel and specific pharmacological modulators of IP3Rs. In addition to being used as a long-sought research tools to study IP3Rs, these compounds will serve as a starting point for development of novel therapeutic approaches to treat diseases associated with aberrant IP3R activity.

项目概要 肌醇 1,4,5-三磷酸受体 (IP3R) 整合激素、生长产生的多种信号 因子、神经递质和代谢状态的变化来调节所有细胞类型的下游信号传导。 IP3R 是配体门控离子通道，进一步受变构和共价机制调节， 介导内质网 (ER) 中 Ca2+ 的释放。由此产生的细胞质和 线粒体 Ca2+ 浓度调节许多生理过程（例如学习、记忆、膜 运输、突触传递、分泌、运动、膜兴奋性、基因表达、细胞分裂和 细胞凋亡）。此外，IP3R 和钙信号传导的病理失调与癌症有关， 神经退行性疾病、自身免疫性疾病和代谢性疾病，使 IP3R 成为治疗以下疾病的有希望的靶标 这些疾病。尽管结构研究最近取得了进展，但有关结构的基本问题 配体相互作用和通道门控的机制大多仍未得到解答，部分原因是大量的 IP3R 的大小和复杂性以及特定药理学工具的可用性有限。 在本提案中，我们将（目标 1）结合冷冻电子显微镜 (cryo-EM) 和 X 射线晶体学 结合基于荧光钙成像的功能性 IP3R 测定来阐明 IP3R 门控循环的一般主题和小分子受体抑制的分子基础。 我们最近发布的数据显示，IP3 结合位点被一个我们称之为“环”的区域占据。 自结合肽（SBP），位于一级序列中较远的位置。我们假设 SBP 是 IP3R 中的一个新型调节位点，可以调节与 IP3 的表观亲和力，从而调节 Ca2+ 通道活动，并且 IP3R 亚型之间 SBP 序列的差异导致了它们的不同 监管属性。我们将对 IP3R 亚型和 SBP 进行（目标 2）功能和结构研究 突变体来检验这一假设并确定这种相互作用的结构决定因素。 完成这些目标将为 IP3R 门控和监管带来无与伦比的机械洞察力， 潜在地导致 IP3R 的新颖且特定的药理调节剂的开发。此外 为了被用作研究 IP3R 的长期研究工具，这些化合物将作为起点 开发新的治疗方法来治疗与异常 IP3R 活性相关的疾病。