PHOTORECEPTOR CELL DEVELOPMENT AND SIGNAL TRANSDUCTION

感光细胞发育和信号传导

• 批准号: 2019871
• 负责人: Richard W. CARTHEW
• 金额: $ 20.29万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2019871
• 关键词: Drosophilidae; SDS polyacrylamide gel electrophoresis; biological signal transduction; cell differentiation; cytogenetics; gel filtration chromatography; gene expression; genetic promoter element; genetic regulatory element; growth factor receptors; immunoprecipitation; molecular cloning; northern blottings; phenotype; protein structure function; protein tyrosine kinase; radionuclides; site directed mutagenesis; southern blotting; transcription factor; visual photoreceptor; western blottings

Receptor tyrosine kinases are important regulatory proteins that control many aspects of cellular metabolism, growth, and differentiation. Many extracellular signaling molecules are known to exert their effects on cell regulation by binding to these receptors. The ultimate objective of the proposed research is to understand the molecular mechanisms that receptor tyrosine kinases use to regulate cellular behavior. This could provide important insights into how these cellular processes are regulated and coordinated, and how inappropriate activation of receptor tyrosine kinases can lead to neoplastic transformation of cells. In order to address this question, we study the differentiation of a photoreceptor cell in the Drosophila eye that is regulated by a receptor tyrosine kinase, the product of the seven less gene. Activation of the seven less receptor results in a single cell to develop as a R7 photoreceptor rather than a non-neuronal cell. The activation of Sevenless serves as a switch that induces expression of the phyllopod gene in the presumptive R7 cell. phyllopod encodes a nuclear protein required for fate determination of the R7 photoreceptor. In previous work, we studied the seven in absentia (sina) gene and found that it also plays a central role in the decision process that is regulated by Sevenless. sina encodes a nuclear protein that is expressed ubiquitously in the eye. Our studies have demonstrated that the Sina and Phyllopod proteins specifically associate to form a complex in vitro. This suggests that both proteins directly interact in presumptive R7 cells, and that the complex is active in regulating R7-specific gene expression. We have conducted a genetic screen for mutations that attenuate sina activity and identified 33 genes. We have characterized one of these genes in detail. The prospero gene becomes transcriptionally activated at a low level in all Sevenless-competent cells prior to Sevenless signaling. This requires activation of the EGF receptor tyrosine kinase. Restriction of high-level prospero transcription to R7 cells appears as a subsequent event, which requires Sevenless activation. Our results suggest that both transcriptional responses are linked to activation of the Ras signal transduction pathway that operates downstream of both receptor tyrosine kinases. The aims of the proposed research are to: (l) biochemically characterize Sina and Phyllopod proteins; (2) conduct molecular characterization of two more genes; (3) uncover the molecular mechanism by which receptor activation of Ras 1 results in two distinct transcriptional responses by the prospero gene.

受体酪氨酸激酶是重要的调节蛋白，控制 细胞代谢、生长和分化的许多方面。许多 已知细胞外信号分子对细胞发挥作用 通过与这些受体结合进行调节。该项目的最终目标是 拟议的研究是为了了解受体的分子机制 酪氨酸激酶用于调节细胞行为。这可以提供 关于这些细胞过程如何调节和的重要见解 受体酪氨酸激酶的不适当激活如何协调 可导致细胞的肿瘤性转化。 为了解决这个问题，我们研究一下 果蝇眼睛中受受体调节的感光细胞 酪氨酸激酶，七少基因的产物。激活 减少 7 个受体导致单个细胞发育为 R7 感光细胞而不是非神经元细胞。七少的激活 作为诱导叶足基因表达的开关 假定的 R7 细胞。叶足类编码命运所需的核蛋白 R7光感受器的测定。在之前的工作中，我们研究了 七缺席（新浪）基因，发现它也起着核心作用 在由 Sevenless 监管的决策过程中。新浪编码a 眼睛中普遍表达的核蛋白。我们的研究有 证明 Sina 和 Phyllopod 蛋白特异性结合 在体外形成复合物。这表明这两种蛋白质直接 在假定的 R7 细胞中相互作用，并且该复合物在 调节 R7 特异性基因表达。 我们对削弱 sina 的突变进行了基因筛查 活性并鉴定出 33 个基因。我们已经表征了这些基因之一 详细。 prospero 基因在低水平下转录激活 在 Sevenless 信号传导之前，所有 Sevenless 感受态细胞中的水平。这 需要激活 EGF 受体酪氨酸激酶。限制 R7 细胞的高水平 prospero 转录出现为后续 事件，需要激活七人。我们的结果表明，两者 转录反应与 Ras 信号的激活有关 在两个受体酪氨酸下游起作用的转导途径 激酶。 拟议研究的目的是：（l）生化表征 新浪和叶足蛋白； (2) 进行两种分子表征 更多基因； (3)揭示受体的分子机制 Ras 1 的激活导致两种不同的转录反应 繁荣基因。