CAAX Processing and Cell Signaling in Dictyostelium

盘基网柄菌中的 CAAX 处理和细胞信号传导

• 批准号: 7364385
• 负责人: Edward C COX
• 金额: $ 31.96万
• 依托单位: PRINCETON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7364385
• 关键词: Address; Amino Acid Motifs; Amino Acids; Animal Model; Antineoplastic Agents; Behavior; Biological Assay; Biological Models; Carbon; Cell Polarity; Cell Signaling Process; Cells; Cellular Morphology; Chemotaxis; Clinical Trials; Condition; Cyclic AMP; Cysteine; Development; Dictyostelium; Dimethylallyltranstransferase; Disease; Embryo; Endopeptidases; Essential Amino Acids; Family; Figs - dietary; G Protein-Coupled Receptor Genes; GTP-Binding Proteins; Genes; Genetic; Genome; Goals; Lead; Ligands; Lipids; Measures; Methylation; Methyltransferase; Molecular; Monomeric GTP-Binding Proteins; Mus; Mutation; Organism; Pathway interactions; Peptide Hydrolases; Pharmacotherapy; Phenotype; Play; Process; Proteins; Range; Research; Role; S-Adenosylmethionine; Signal Transduction; Signaling Protein; Specific qualifier value; System; Technology; Time; Tissues; Transferase; acetaminophen cysteine; base; cancer cell; cell growth; demethylation; design; drug development; extracellular; genetic analysis; inhibitor/antagonist; member; mutant; prenyl; prenylation; research study; response; rho; thioether; tool; tumor; tumorigenic

DESCRIPTION (provided by applicant): A central issue in healthy and diseased cells is how cells sense signals from the outside, and how these signals are used to organize cellular responses. The small GTPase families Ras and Rho are intimately involved in these processes, and mutations in them often lead to the disease state. Thus it has been known for many years that activating mutations in Ras are common in cancer cells, and it is widely believed that Ras mutations are essential for the genesis of mammalian tumors. Most small GTPases carry a CAAX amino acid motif at their C terminus, where C is cysteine, AA are usually two aliphatic amino acids, and X specifies whether the protein will be modified with the 15 carbon farnesyl lipid or the 20 carbon geranylgeranyl lipid. Ras function in the cell requires the CAAX sequence, and for activated Ras to be tumorigenic, the CAAX sequence must be modified by a prenylation pathway. For this reason the pathway is a potential target for anticancer drug therapy. Recent drug development efforts have validated this assumption, with several promising new inhibitors of the pathway now in clinical trials. Much remains to be known about many the prenylation pathway: which of the small G proteins must be methylated for them to be modulated, how methylation levels are controlled by extra- and intracellular signals, how the three partners in the prenylation pathway are regulated if they are, the consequences for cell morphology and response to signals when various of the prenylation steps are reduced or absent, and the role that methylation plays in the very earliest steps of G-coupled response to ligand, are some of the outstanding questions addressed in this proposal. The aim of this research is to use Dictyostelium as a model system to understand these important questions. Preliminary experiments reveal that deletions in the methylation gene block early signaling and response to cAMP, but not cell growth. Various signaling proteins are mislocalized in this deletion, chemotaxis and cAMP responses are disrupted, and the ability of cells to develop into a coherent tissue is blocked. These observations will be extended using assays that will correlate cellular behavior with molecular changes, and by developing a panel of mutants deficient in each step in the prenylation pathway.

描述(申请人提供)：健康和患病细胞的一个中心问题是细胞如何感知来自外部的信号，以及这些信号如何被用来组织细胞反应。小的GTP酶家族RAS和RHO与这些过程密切相关，它们的突变通常会导致疾病状态。因此，多年来人们已经知道RAS的激活突变在癌细胞中很常见，人们普遍认为RAS突变在哺乳动物肿瘤的发生中是必不可少的。大多数小的GTP酶在其C末端带有一个CAAX氨基酸基序，其中C是半胱氨酸，AA通常是两个脂肪族氨基酸，X指定蛋白质是用15碳的法尼基类脂还是20碳的香叶基类脂修饰。RAS在细胞中的功能需要CAAX序列，而为了使激活的RAS具有致瘤性，CAAX序列必须通过预烯基化途径进行修饰。因此，该通路是抗癌药物治疗的潜在靶点。最近的药物开发工作证实了这一假设，目前有几种前景看好的该途径的新抑制剂正在进行临床试验。对于许多预烯基化途径仍有许多未知之处：哪些小G蛋白必须甲基化才能被调控，甲基化水平是如何由细胞外和细胞内信号控制的，如果甲基化途径中的三个伙伴是如何调控的，当各种预烯基化步骤减少或缺失时，对细胞形态和信号反应的影响，以及甲基化在G偶联对配体的反应的最早步骤中所起的作用，是本提案中解决的一些悬而未决的问题。本研究的目的是以网柄网柄菌为模型系统来理解这些重要问题。初步实验表明，甲基化基因的缺失阻止了早期信号和对cAMP的反应，但不会阻止细胞生长。在这种缺失中，各种信号蛋白被错误定位，趋化性和cAMP反应被扰乱，细胞发育成连贯组织的能力被阻断。这些观察将通过将细胞行为与分子变化相关联的分析来扩展，并通过开发一组在预烯基化途径的每一步中都有缺陷的突变体来扩展。