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.

项目摘要 肌醇1,4,5-三磷酸酯受体（IP3RS）整合由激素产生的多种信号，生长 因素，神经递质以及代谢状态的变化以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，由变构和共价机制进一步调节， 从内质网（ER）中介导Ca2+释放。导致的细胞质和 线粒体Ca2+浓度调节许多生理过程（例如，学习，记忆，膜 运输，突触传播，分泌，运动，膜兴奋性，基因表达，细胞分裂和 凋亡）。此外，IP3RS和钙信号传导的病理失调与癌症有关， 神经退行性，自身免疫性和代谢疾病，使IP3RS有望治疗目标 这些疾病。尽管结构研究最近取得了进步，但有关 配体相互作用和通道门控的机制主要是未解决的，部分原因是很大 IP3RS的大小和复杂性以及特定药理工具的可用性有限。 在此提案中，我们将（AIM 1）结合冷冻电子显微镜（Cryo-EM）和X射线晶体学 基于基于荧光的钙成像的功能性IP3R分析，以阐明 小分子抑制受体抑制的IP3R门控循环的一般主题。 我们最近发布的数据显示，IP3绑定站点被我们称为的循环占据 自我结合肽（SBP），位于主要序列中。我们假设 SBP是IP3RS中新型的调节站点，可以调节对IP3的明显亲和力，从而CA2+ 通道活动，以及IP3R子类型之间SBP序列的差异有助于其独特 监管特性。我们将对IP3R亚型和SBP进行（AIM 2）功能和结构研究 突变体检验该假设并确定这种相互作用的结构决定因素。 这些目标的完成将产生无与伦比的机械洞察IP3R门控和调节， 有可能导致IP3RS的新型和特定药理调节剂的发展。此外 为了用作研究IP3RS的长期研究工具，这些化合物将成为起点 用于开发新型治疗方法，以治疗与异常IP3R活性相关的疾病。