A EUKARYOTIC TISSUE DENSITY SENSOR

真核组织密度传感器

• 批准号: 3301283
• 负责人: Richard H Gomer
• 金额: $ 9.68万
• 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/3301283
• 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.

该提案涉及真核质量效应器：细胞外 允许组织内的单个细胞感知的分子 整个组织的质量。 这样的分子将集中在 参与发育伤口期间生长的调节 愈合和组织再生。 大众传感的破坏 机制可能导致肿瘤形成。 作为一个模型系统，我们 将使用发育所分泌的条件培养基因子（CMF） 盘基网柄菌细胞。 在单层深层培养中， 盘基网柄菌细胞在高细胞密度下分化，但不分化 低密度；然而，低密度的细胞会分化 在高密度细胞先前处于饥饿状态的培养基中 （条件培养基）。 对这一现象的解释是 在发育过程中，盘基网柄菌细胞需要能够感知 他们是否距离聚合中心较远，因此需要 继续表达聚集特异性基因，或者它们是否 位于聚合中心或附近，因此需要继续 表达聚集特定基因，或者它们是否处于或 靠近聚合中心，因此可以开始表达 分化特异性基因。 自从开发盘基网柄菌以来 细胞不分裂，CMF 是质量效应器而不是有丝分裂原 或生长因子。 在高等真核生物中，人们可以想象类似的 具有不同效应器和受体的机制，使肝脏 细胞可以感知其他肝细胞、胰腺细胞的数量 其他胰腺细胞的数量等。 条件培养基显示允许低密度的活性 细胞分化与 70 kD 蛋白质以及 具有约 5 kD 的分子；有趣的是，这两个分子都具有 相同的活动，不需要组合起来才能允许 差异化。 5 kD CMF 以及它们是否相关 和/或如果一个是从另一个派生的。 编码70的基因 kD CMF 将被分离并测序，以便与其他 已知的蛋白质。 如果 5 kD CMF 是多肽，则其基因将 类似地进行表征。 CMF的生理作用是 通过表征其时间调节来检查 分泌，哪些细胞类型分泌它，可能的因素 调节其分泌及其与 盘基网柄菌 cAMP 介导的趋化机制。 长期来看 目标是在分子基础上了解整个转导 细胞感知是否存在的机制 大量其他细胞。