Signalling Processes in Dictyostelium

盘基网柄菌的信号传导过程

• 批准号: 8261828
• 负责人: RICHARD A FIRTEL
• 金额: $ 52.66万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-07-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8261828
• 关键词: Adenylate Cyclase; Bacterial Infections; Behavior; Binding; Biochemical; Biological; Biological Process; Cell surface; Cells; Chemicals; Chemotactic Factors; Chemotaxis; Complex; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cytoskeleton; Development; Dictyostelium; Eukaryota; Event; F-Actin; Family; Feedback; Food; Future; G-Protein-Coupled Receptors; Genetic; Glycogen Synthase Kinase 3; Goals; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Human; Individual; Infection; LRRK2 gene; Lateral; Leukocytes; Light; Link; Mammalian Cell; Mammary Neoplasms; Mediating; Molecular; Morphogenesis; Motor; Movement; Myosin Type II; Natural Immunity; Neoplasm Metastasis; Null Lymphocytes; Parkinson Disease; Pathway interactions; Phosphotransferases; Play; Population; Process; Protein Kinase; Proteins; Receptor Protein-Tyrosine Kinases; Regulation; Regulatory Pathway; Research; Role; Series; Side; Signal Pathway; Signal Transduction; Sirolimus; Site; Source; System; Time; Work; Wound Healing; autocrine; base; cancer cell; cell motility; cell type; computerized data processing; crosslink; extracellular; filamin; human disease; in vivo; insight; link protein; macrophage; member; migration; neoplastic cell; neutrophil; novel; paracrine; polarized cell; polymerization; protein crosslink; response; social; tissue repair; tool

DESCRIPTION (provided by applicant): Chemotaxis, or directional movement of cells up a chemical gradient, plays important roles in a wide range of cellular behaviors. Naive, randomly moving cells, such as leukocytes and Dictyostelium cells must be able to directionally sense extremely shallow extracellular chemoattractant gradients and respond by establishing a polarized cytoskeleton with an F-actin-based protruding pseudopod or lamellipod at the leading edge and a contractile trailing edge. This polarization is achieved through the spatially restricted amplification of the external gradient through the localized activation of pathways at the site of the cortex closest to the chemoattractant source. While significant advancements have been made in identifying many components that control chemotaxis, we do not yet understand how cells sense the direction of the gradient and restrict responses to the leading edge, how newly polymerized F-actin networks are stabilized to form pseudopod, or what regulates the timing of these events. Furthermore, chemotaxing cells are able to communicate, within the cell population, to organize more global social responses, such as the autocrine aggregation response in Dictyostelium cells in which cells respond to and then secrete the chemoattractant cAMP leading to the coordinate aggregation of ~105 cells (signal relay) or the paracrine response system used by macrophages and mammary tumor cells, resulting in interdependent migration of the two cell types during metastasis. As many of the pathways are evolutionarily conserved, we will use Dictyostelium to achieve three important goals: 1) We have demonstrated that TORC2, through the activation of PKB and PKBR1, integrates multiple inputs to regulate chemotaxis by controlling directional sensing and F-actin polymerization, and to control signal relay through the regulation of adenylyl cyclase. Furthermore, we have found that cAMP, through the activation of PKA, acts as an important feedback loop to negatively regulate the TORC2/PKB:PKBR1 pathway. We will investigate the molecular basis of this key feedback loop. 2) We have found that GSK-3 is an important regulator of chemotaxis and by comparing the phosphoproteomes of wild-type and GSK-3 null cells have identified putative GSK-3 substrates, including known components of the Ras/Rap1/F-actin pathways that control chemotaxis. Our goal is to define key GSK- 3 substrates and understand how GSK-3 functions to control chemotaxis. 3) We have identified a novel regulatory pathway that plays a central role in forming and stabilizing the pseudopod during chemotaxis. We have shown that Rab1A binds to and is required to activate Roco2, a member of the Roco family of GTPase-containing protein kinases. Roco2 acts upstream of the F-actin cross- linking protein filamin and both are required for pseudopod extension. We will examine the mechanism by which this pathway is regulated and how it controls chemotaxis. PUBLIC HEALTH RELEVANCE: The research will focus on understanding the basic mechanisms by which cells are able to directionally move in response to a chemical gradient or chemotaxis, a process that is used by cells during wound repair, bacterial infection, and metastasis of cancer cells. The findings illuminated by the proposed work will shed light on the molecular basis of human disease and may help, in the future, identify new targets for treatment.

描述（由申请人提供）：趋化性，或细胞沿化学梯度的定向运动，在广泛的细胞行为中发挥着重要作用。幼稚的、随机移动的细胞，如白细胞和盘基网柄菌细胞，必须能够定向感知极浅的细胞外趋化剂梯度，并通过建立极化细胞骨架做出反应，该骨架的前缘具有基于 F-肌动蛋白的突出伪足或片状足，后缘具有收缩性。这种极化是通过在最靠近化学引诱剂源的皮层部位局部激活外部梯度的空间受限放大来实现的。 虽然在识别许多控制趋化性的成分方面已经取得了重大进展，但我们还不了解细胞如何感知梯度方向并限制对前缘的反应，新聚合的 F-肌动蛋白网络如何稳定形成伪足，或者是什么调节这些事件的时间。此外，趋化细胞能够在细胞群内进行交流，组织更多的全局社会反应，例如盘基网柄菌细胞中的自分泌聚集反应，其中细胞响应并分泌趋化剂 cAMP，导致约 105 个细胞的协调聚集（信号中继）或巨噬细胞和乳腺肿瘤细胞使用的旁分泌反应系统，导致两种细胞类型在 转移。由于许多途径在进化上是保守的，我们将使用盘基网柄菌来实现三个重要目标：1）我们已经证明TORC2通过激活PKB和PKBR1，整合多个输入来通过控制定向传感和F-肌动蛋白聚合来调节趋化性，并通过调节腺苷酸环化酶来控制信号传递。此外，我们发现cAMP通过激活PKA，作为重要的反馈环路负向调节TORC2/PKB:PKBR1通路。我们将研究这个关键反馈回路的分子基础。 2)我们发现GSK-3是趋化性的重要调节剂，通过比较野生型和GSK-3无效细胞的磷酸化蛋白质组，已经鉴定出推定的GSK-3底物，包括控制趋化性的Ras/Rap1/F-肌动蛋白途径的已知成分。我们的目标是定义关键的 GSK-3 底物并了解 GSK-3 如何发挥控制趋化性的作用。 3）我们已经确定了一种新的调控途径，它在趋化过程中伪足的形成和稳定中发挥着核心作用。我们已经证明，Rab1A 与 Roco2 结合，并且是激活 Roco2 所必需的，Roco2 是含有 GTPase 的蛋白激酶 Roco 家族的成员。 Roco2 作用于 F-肌动蛋白交联蛋白丝蛋白的上游，两者都是伪足延伸所必需的。我们将研究该途径的调节机制以及它如何控制趋化性。 公共健康相关性：该研究将重点了解细胞能够响应化学梯度或趋化性而定向移动的基本机制，这是细胞在伤口修复、细菌感染和癌细胞转移过程中使用的过程。拟议工作所阐明的发现将揭示人类疾病的分子基础，并可能有助于在未来确定新的治疗目标。