Calcium Signals Within Membrane Nanotubes

膜纳米管内的钙信号

• 批准号: 8450765
• 负责人: Ian F Smith
• 金额: $ 25.97万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8450765
• 关键词: Accounting; Action Potentials; Alzheimer' s Disease; Architecture; Axon; Buffers; Calcium; Calcium Signaling; Caliber; Cell Communication; Cell Surface Extensions; Cells; Cellular Stress; Characteristics; Chemicals; Communication; Communications Media; Cultured Cells; Diabetes Mellitus; Diffuse; Diffusion; Disease; Distant; Endoplasmic Reticulum; Event; Fire - disasters; Gap Junctions; Gene Expression; Goals; ITPR1 gene; Image; Imaging Techniques; Imaging technology; Individual; Inositol; Ions; Lead; Length; Link; Malignant Neoplasms; Mammalian Cell; Maps; Mediating; Membrane; Microscopy; Movement; Nanotubes; Nature; Organelles; Organism; Pathogenesis; Physiological; Physiological Processes; Physiology; Process; Property; Proteins; Role; Route; Shapes; Signal Transduction; Site; Stress; Study models; Synapses; System; Time; Tubular formation; analog; calcium indicator; cell motility; electric impedance; enzyme activity; information processing; insight; intercellular communication; meetings; models and simulation; nanometer; nanoscale; neuronal cell body; novel; receptor; regenerative; response; single molecule; transmission process

DESCRIPTION (provided by applicant): Intercellular communication is an absolute requirement for the coordinated functioning of multi-cellular organisms, and cells have long been known to employ gap junctions and synapses to communicate with their neighbors. A new route of cell-to-cell communication has recently been identified via tunneling membrane nanotubes (TNTs). These are dynamic membrane protrusions, a few hundred nanometers in diameter, that physically link cell bodies over distances of tens of microns and allow for the exchange of cytosolic molecules, membrane components and even organelles between neighboring cells. Transmission of Ca2+ signals along TNTs has been proposed as a means of intercellular communication, which may regulate physiological processes as diverse as gene expression, enzyme activity and electrical excitability. Our modeling studies indicate that passive diffusion of Ca2+ ions along TNTs is inadequate to support efficient transmission of Ca2+ signals between cells. Instead, our observations of local spontaneous and inositol trisphosphate-evoked Ca2+ signals generated within the length of TNTs formed between cultured mammalian cells suggest a mechanism for active propagation of intercellular Ca2+ signals along TNTs. We thus hypothesize that clusters of Ca2+- activated Ca2+ release channels function as amplification sites to overcome limitations of passive diffusion in a chemical analog of electrical transmission of action potentials along axons. Our overall goals are to elucidate the mechanisms underlying this novel mechanism of Ca2+ wave propagation along TNTs, and to explore its role in the physiological and pathological cell-cell communication of Ca2+ signals. Our specific aims are; (1) Using fluorescent calcium indicators we will determine the mechanisms and types of Ca2+ channels involved in regenerative local Ca2+ release events within TNTs, and elucidate the sequestration/buffering systems that shape these localized events in time and space. (2) Utilizing novel superresolution imaging techniques we will map individual Ca2+ release channels with nanometer precision along the TNT and, employing single molecule superresolution imaging, we will explore the diffusional motility of IP3Rs and the contiguous nature of the endoplasmic reticulum along its length. (3) We will explore how local calcium release events coordinate with one another to propagate a Ca2+ wave, the requirements for this process to occur efficiently, and investigate the role for TNTs in spreading aberrant Ca2+ signals in response to cellular stress. Our proposal will provide important mechanistic insights into TNT-mediated propagation of Ca2+ signals and will likely lead to significant advances in our understanding of the physiology and pathophysiological processes involved in this novel mechanism of cell-to-cell communication.

描述（由申请人提供）：细胞间通讯是多细胞生物体协调功能的绝对要求，人们早就知道细胞利用间隙连接和突触与邻居进行通讯。最近通过隧道膜纳米管（TNT）发现了一种新的细胞间通讯途径。这些是动态的膜突起，直径为几百纳米，在物理上连接数十微米距离的细胞体，并允许相邻细胞之间交换胞质分子、膜成分甚至细胞器。 Ca2+信号沿着TNT的传输被认为是细胞间通讯的一种手段，它可以调节基因表达、酶活性和电兴奋性等多种生理过程。我们的建模研究表明，Ca2+ 离子沿 TNT 的被动扩散不足以支持细胞间 Ca2+ 信号的有效传输。相反，我们对培养哺乳动物细胞之间形成的 TNT 长度内产生的局部自发和肌醇三磷酸诱发的 Ca2+ 信号的观察表明，细胞间 Ca2+ 信号沿着 TNT 主动传播的机制。因此，我们假设 Ca2+ 激活的 Ca2+ 释放通道簇充当放大位点，以克服沿轴突动作电位电传输的化学模拟中被动扩散的限制。我们的总体目标是阐明这种 Ca2+ 波沿 TNT 传播的新机制，并探索其在 Ca2+ 信号的生理和病理细胞间通讯中的作用。我们的具体目标是； (1) 使用荧光钙指示剂，我们将确定参与 TNT 内再生局部 Ca2+ 释放事件的 Ca2+ 通道的机制和类型，并阐明在时间和空间上塑造这些局部事件的封存/缓冲系统。 (2) 利用新颖的超分辨率成像技术，我们将沿 TNT 以纳米精度绘制单个 Ca2+ 释放通道，并利用单分子超分辨率成像，我们将探索 IP3R 的扩散运动和内质网沿其长度的连续性质。 (3) 我们将探讨局部钙释放事件如何相互协调以传播 Ca2+ 波、这一过程有效发生的要求，并研究 TNT 在传播响应细胞应激的异常 Ca2+ 信号中的作用。我们的提议将为 TNT 介导的 Ca2+ 信号传播提供重要的机制见解，并可能导致我们对这种新的细胞间通讯机制所涉及的生理学和病理生理学过程的理解取得重大进展。