A EUKARYOTIC TISSUE DENSITY SENSOR

真核组织密度传感器

• 批准号: 3301284
• 负责人: Richard H Gomer
• 金额: $ 10.1万
• 依托单位: RICE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-07-01 至 1993-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3301284
• 关键词: Dictyostelium; biological signal transduction; biosensor device; cell population study; chemotaxis; cyclic AMP; cytogenetics; eukaryote; extracellular matrix; gene expression; high performance liquid chromatography; isotope dilution method; molecular cloning; molecular genetics; nucleic acid probes; nucleic acid sequence; protein structure function; regeneration; secretion; tissue /cell culture; wound healing

This proposal concerns eucaryotic mass effectors: extracellular molecules that allow individual cells within a tissue to sense the mass of the entire tissue. Such molecules would be centrally involved in the regulation of growth during development wound healing and tissue regeneration. Disruption of the masssensing mechanism could lead to tumor formation. As a model system, we will use the conditioned medium factor (CMF) secreted by developing Dictyostelium discoideum cells. In submerged monolayer culture, Dictyostelium cells differentiate at high cell densities but not at low densities; cells at low densities will however differentiate in medium in which a high density of cells was previously starved (a conditioned medium). An explanation this phenomenon is that during development, Dictyostelium cells need to be able to sense whether they are far from an aggregation center and thus need to continue expressing aggregation specific genes, or whether they are at or near an aggregation center and thus need to be continue expressing aggregation specific genes, or whether they are at or near an aggregation center and thus can begin expressing differentiation- specific genes. Since developing Dictyostelium cells do not divide, CMF is a mass effector rather than a mitogen or growth factor. In higher eucaryotes, one could envision similar mechanisms with different effectors and receptors so that liver cell could sense the number of other liver cells, pancreas the number of other pancreas cells, etc. Fractionation of the conditioned medium shows that the activity that allows low density cells to differentiate copurifies with a 70 kD protein as well as with a ~5 kD molecule; interestingly, the two molecules both have the same activity and do not need to be combined to allow differentiation. The 5 kD CMF's and whether they are related and/or if one is derived from the other. The gene encoding the 70 kD CMF will be isolated and sequenced for comparison with other known proteins. If the 5 kD CMF is a polypeptide, its gene will similarly be characterized. The physiological role of CMF will be examined by characterizing the temporal regulation of its secretion, which cell types secrete it, possible factors that might regulate its secretion and the extent of its interaction with the Dictyostelium cAMP mediated chemotaxis mechanism. The long term goal is to understand on a molecular basis the entire transduction mechanism whereby cells sense whether they are in the presence of a large mass of other cells.

该建议涉及桉树质量效应：细胞外 允许组织中单个细胞感知的分子 整个组织的质量。 这样的分子将是集中的 参与发育伤口期间增长的调节 愈合和组织再生。 群众的破坏 机制可能导致肿瘤形成。 作为模型系统，我们 将使用开发的条件中等因素（CMF） dictyostelium discoideum细胞。 在淹没的单层文化中， dictyostelium细胞在高细胞密度下分化，但没有 在低密度下；但是，低密度的细胞将有区别 在先前饥饿的高密度的培养基中 （条件培养基）。 这种现象的解释是 在开发过程中，dictyostelium细胞需要能够感知 它们是否远离聚合中心，因此需要 继续表达汇总特定基因，或者它们是否是 在聚合中心或附近，因此需要继续 表达汇总特定基因，或它们是否处于或 在聚合中心附近，因此可以开始表达 分化特异性基因。 自开发柱状固有 细胞不划分，CMF是质量效应器，而不是有丝分裂的 或生长因子。 在较高的桉树中，可以设想类似 具有不同效应子和受体的机制，使肝脏 细胞可以感觉到其他肝细胞的数量，胰腺 其他胰腺细胞等数量。 条件培养基表明，允许低密度的活动 细胞以70 kD蛋白以及 用约5 kD分子；有趣的是，两个分子都有 相同的活动，不需要合并以允许 分化。 5 kd CMF以及它们是否相关 和/或一个是从另一个派生的。 编码70的基因 KD CMF将被隔离并测序以与其他 已知蛋白质。 如果5 kD CMF是多肽，则其基因将 类似地被描述。 CMF的生理作用将是 通过表征其时间调节的检查 分泌细胞类型分泌的分泌，可能的因素可能 调节其分泌物以及其与 dictyostelium CAMP介导的趋化性机制。 长期 目标是从分子理解整个转导 细胞感知它们是否存在的机制 大量其他细胞。