FEEDBACK REGULATION OF POLYAMINE SYNTHESIS AND TRANSPORT

多胺合成和运输的反馈调节

• 批准号: 3283935
• 负责人: JOHN L A MITCHELL
• 金额: $ 16.06万
• 依托单位: NORTHERN ILLINOIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3283935
• 关键词: Xenopus; biological transport; cell growth regulation; clone cells; enzyme activity; enzyme biosynthesis; enzyme feedback; enzyme inhibitors; laboratory rabbit; metabolism; ornithine decarboxylase; polyamines; protein biosynthesis; tissue /cell culture

The polyamines, spermidine and spermine, and their diamine precursor, putrescine, are found in all mammalian cells and are essential for cell growth and viability. Mammalian cells obtain the requisite polyamines by biosynthesis or, if available, by uptake from their environment. In normal cells, intracellular levels of the polyamines are carefully managed, whereas cancer cells and virally transformed cells frequently exhibit abnormal elevations of these compounds. Because of this correlation, there is intense current interest in the development of inhibitors of polyamine synthesis for use as anti-neoplastic, and even anti-carcinogenic, agents. Cancer cells also are noted to incorporate exogenous polyamines more readily than normal cells. Investigators are attempting to exploit this attribute to facilitate the selective incorporation of potentially cytotoxic polyamine analogs into tumor cells. Both these approaches have proven somewhat disappointing so far, in large part because we do not understand the normal control mechanisms utilized by a cell in maintaining polyamine levels. For these reasons, the long-term goal of this project is to elucidate, and potentially to control, the complex of mechanisms whereby mammalian cells regulate the intracellular polyamines levels that are essential for normal physiology. Biochemical and molecular techniques, as well as several hamster and rat cell lines, will be used to investigate three different aspects of polyamine maintenance: a) synthesis of the critical biosynthetic enzyme, ornithine decarboxylase; b) turnover of this enzyme; and c) active polyamine transport. All three processes are sensitively regulated by alterations in polyamine levels. Recently, a variant rat cell line was discovered that is simultaneously deficient in all of these polyamine-feedback responses. This observation suggests that some aspect of an essential spermidine-sensitive reaction is common to these three different cell processes, and this shared intermediate or reaction is deficient in the variant cell line. In the proposed investigation, the mechanism of polyamine feedback that is deficient in the variant cell line will be determined, thereby establishing a common link between the feedback control of ornithine decarboxylase stability, of which something is known, and those of ornithine decarboxylase synthesis and polyamine transport, about which very little is known. This examination of three different control points in the maintenance of cellular polyamine levels will yield a comprehensive understanding of polyamine homeostasis in normal and cancerous mammalian cells, and will guide future efforts to alter abnormal growth by manipulating cellular polyamines.

多胺、亚精胺和精胺及其二胺前体， 腐胺存在于所有哺乳动物细胞中，对于细胞的形成至关重要 生长和生存能力。 哺乳动物细胞通过以下方式获得必需的多胺 生物合成，或者如果有的话，通过从环境中摄取。 在 正常细胞，细胞内多胺的水平被仔细检测 控制，而癌细胞和病毒转化细胞经常 这些化合物表现出异常升高。 因为这 相关性，目前人们对开发的兴趣浓厚 多胺合成抑制剂，用于抗肿瘤，甚至 抗癌、剂。 癌细胞还被注意到整合 与正常细胞相比，更容易吸收外源性多胺。 调查人员正在 试图利用这个属性来促进选择性 将具有潜在细胞毒性的多胺类似物掺入肿瘤中 细胞。 到目前为止，这两种方法都被证明有些令人失望， 很大程度上是因为我们不了解正常的控制机制 被细胞用来维持多胺水平。 由于这些原因， 该项目的长期目标是阐明并可能 控制，哺乳动物细胞调节的复杂机制 细胞内多胺水平对于正常生理至关重要。 生化和分子技术，以及几种仓鼠和大鼠 细胞系，将用于研究三个不同方面 多胺维持：a) 关键生物合成酶的合成， 鸟氨酸脱羧酶； b) 该酶的周转率； c) 主动 多胺运输。 所有三个过程均受到敏感调节 多胺水平的变化。 最近，一种变异的大鼠细胞系被 发现同时缺乏所有这些 多胺反馈反应。 这一观察结果表明，某些方面 基本的亚精胺敏感反应对于这三种物质来说是共同的 不同的细胞过程，并且这个共享的中间体或反应是 变异细胞系缺陷。 在拟议的调查中， 变异细胞中缺乏的多胺反馈机制 线路将被确定，从而在 鸟氨酸脱羧酶稳定性的反馈控制，其中一些 已知，以及鸟氨酸脱羧酶合成和多胺的那些 运输，人们对此知之甚少。 本次考试共三 维持细胞多胺水平的不同控制点 将全面了解多胺稳态 正常和癌性哺乳动物细胞，并将指导未来的努力 通过操纵细胞多胺来改变异常生长。