THE CYTOLOGICAL AND PHYSIOLOGICAL MODE OF AP4A ACTION

AP4A 作用的细胞学和生理模式

• 批准号: 3178121
• 负责人: ELIEZER RAPAPORT
• 金额: $ 12.36万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-04-01 至 1988-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3178121
• 关键词: Escherichia coli; Kupffer's cell; acute phase protein; adenosine triphosphate; aminoacyl tRNA; cell bank /registry; cell growth regulation; cell nucleus; metastasis; molecular weight; monoclonal antibody; mutant; nucleotide metabolism; platelet aggregation; stress; thrombocytopenia; tissue /cell culture

Diadenosine 5' ,5'''-P1,P4-tetraphosphate (Ap4A), a nucleotide formed in the back reaction of the aminoacid activation step, is ubiquitously present in bacterial and animal cells. The enzyme-catalyzed synthesis of Ap4A from ATP and certain aminoacyladenylates is enhanced by the presence of Zn2+. Several lines of evidence point to possible involvement of Ap4A in aspects of cellular proliferation, DNA replication, heat shock response and cell oxidation. An Ap4A binding protein, which is associated with the high molecular weight form of DNA polymerase alpha of calf thymus and HeLa cell and which binds Ap4A noncovalently with high affinity and great substrate specificity, has been isolated and characterized. Relatively high levels of Ap4A are present in blood platelets and these Ap4A pools are quantitatively released when platelets are induced to aggregate. Our working hypothesis is that Ap4A may be a signal for the induction of the heat shock or stress response in bacterial and animal cells as well as a possible signal for the induction of the host acute phase responses to a variety of infections, injury, and other physical insults in live animals. The physiological response of live animals could be mediated by increases in plasma Ap4A levels produced by platelets' aggregation, which is induced by the above-mentioned trauma. The heat shock or acute phase response is manifested by induction of the synthesis of groups of proteins (different proteins for each of these two phenomena) which presumably enable the individual cells or the whole animal to adapt to external conditions which affect cellular growth or survival. The proposed project is designed to: (1) elucidate the mechanism of cellular Ap4A synthesis in bacterial and animal cells; (2) study the mechanism of Ap4A interaction with the DNA replicative machinery in mammalian cells; (3) establish the physiological response of animals (rats, mice) to increase in serum Ap4A levels which may be produced by thrombocytopenia; and, (4) identify the role of Ap4A in tumor metastasis in light of the recently identified correlations between cellular Ap4A metabolism and the metastatic propensity of cells, and the well-established relationship between platelets' aggregation and tumor metastases in vivo. The long term objectives of these studies are the understanding of Ap4A action at the cellular and physiological levels. The significance of the proposed project is in establishing the mode and mechanism of action of a potential intracellular mediator which signals the cellular response to external conditions affecting growth or survival. (G)

二腺苷5'，5“"-P1，P4- 四磷酸（Ap4A），形成的核苷酸 在氨基酸活化步骤的逆反应中， 存在于细菌和动物细胞中。 酶催化合成 AP4A从ATP和某些氨酰腺苷酸是增强的存在 的Zn2个以上. 有几条证据表明， AP4A在细胞增殖、DNA复制、热休克等方面 反应和细胞氧化。 的Ap4一种结合蛋白 与高分子量形式的DNA聚合酶α相关， 牛胸腺和HeLa细胞，并结合Ap4非共价地与高 亲和性和很大的底物特异性，已被分离， 表征了 相对较高的Ap水平4A存在于血液中 血小板和这些Ap4当血小板聚集时， 被诱导聚集。 我们的工作假设是，4A可以是 诱导细菌热休克或应激反应的信号 和动物细胞以及诱导宿主的可能信号 对各种感染、损伤和其他疾病的急性期反应 对活体动物的身体侮辱。 肝脏的生理反应 动物可通过血浆Ap升高介导4A级由 血小板聚集，这是由上述创伤引起的。 热休克或急性期反应是通过诱导 蛋白质组的合成（这两种蛋白质中的每一种都是不同的蛋白质） 这些现象可能使单个细胞或整个动物 以适应影响细胞生长或存活的外部条件。 本项目的目的是：（1）阐明 蜂窝Ap4在细菌和动物细胞中合成;（2）研究 Ap机制4与DNA复制机制的相互作用 哺乳动物细胞;（3）建立动物（大鼠， 小鼠）血清Ap增加4A级可能产生的 血小板减少症;（4）确定Ap的作用4A在肿瘤转移中的作用 根据最近发现的细胞Ap4一 细胞的代谢和转移倾向，以及公认的 血小板聚集与肿瘤转移的关系 这些研究的长期目标是了解Ap4一 在细胞和生理水平上的作用。 的意义 拟议的项目是建立一个行动模式和机制， 潜在的细胞内介质，其发出细胞响应的信号， 影响生长或生存的外部条件。 （G）