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: 7798229
• 负责人: Edward C COX
• 金额: $ 30.25万
• 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/7798229
• 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; Cyclic AMP; Cysteine; Development; Dictyostelium; Dimethylallyltranstransferase; Disease; Embryo; Essential Amino Acids; Family; Figs - dietary; G Protein-Coupled Receptor Genes; GTP-Binding Proteins; Genes; Genetic; Goals; Lead; Ligands; Lipids; Measures; Methylation; Methyltransferase; Molecular; Monomeric GTP-Binding Proteins; Mus; Mutation; Organism; Pathway interactions; Peptide Hydrolases; Pharmacotherapy; Play; Process; Proteins; 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; genome-wide; inhibitor/antagonist; member; molecular phenotype; 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（由申请人提供）：健康细胞和病变细胞的核心问题是细胞如何感知来自外部的信号，以及这些信号如何用于组织细胞反应。GTPase小家族Ras和Rho与这些过程密切相关，它们的突变经常导致疾病状态。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，并且人们普遍认为Ras突变对哺乳动物肿瘤的发生至关重要。大多数小gtpase在其C端携带CAAX氨基酸基序，其中C是半胱氨酸，AA通常是两个脂肪氨基酸，X指定蛋白质将被15碳的法尼基脂质或20碳的香叶基脂质修饰。Ras在细胞中的功能需要CAAX序列，激活的Ras要具有致瘤性，CAAX序列必须通过前置化途径修饰。因此，该途径是抗癌药物治疗的潜在靶点。最近的药物开发工作已经证实了这一假设，几种有希望的新途径抑制剂正在临床试验中。关于戊酰化途径，我们还有很多需要了解的地方：哪些小G蛋白必须被甲基化才能被调节，甲基化水平是如何被细胞外和细胞内信号控制的，如果是的话，前酰化途径中的三个伙伴是如何被调节的，当各种前酰化步骤减少或缺失时，细胞形态和对信号的反应的后果，甲基化在G偶联配体反应的最早步骤中所起的作用，是本提案中讨论的一些悬而未决的问题。本研究的目的是利用盘基骨柱作为模型系统来理解这些重要问题。初步实验表明，甲基化基因的缺失会阻断早期信号传导和对cAMP的反应，但不会阻断细胞生长。在这种缺失中，各种信号蛋白被错误定位，趋化性和cAMP反应被破坏，细胞发育成连贯组织的能力被阻断。这些观察结果将通过将细胞行为与分子变化联系起来的分析，以及通过开发一组在前置酰化途径的每个步骤中都缺乏的突变体来扩展。