MECHANISM OF PHORBOL ESTER-INDUCED LIPID METABOLISM

拟议的研究涉及定义近端细胞内事件 参与促进肿瘤的佛波酯的作用。具体来说， 花生四烯酸释放和释放的生化机制 用GH3大鼠脑垂体研究磷脂酰胆碱代谢 细胞。尽管有人提出，磷脂酶的刺激 A2和磷脂酶C分别是这些事件的起因， 目前还缺乏确凿的证据。这些活动之所以重要，是因为 来自多种细胞类型的累积证据表明：1)花生四烯酸 和/或代谢产物可能介导促肿瘤和2)卵磷脂 新陈代谢似乎特别与佛波酯的作用有关。 GH3细胞为这些研究提供了一个很好的模型，因为1)它们是 允许明确分配变化的同质细胞群 一种特定的细胞类型和2)对蛋白激酶C的广泛研究， 推测佛波酯受体已在这些细胞中执行。 关于完整细胞研究中涉及的酶反应的建议 将在亚细胞部分得到确认。无论是蛋白激酶C还是 佛波醇酯的另一个细胞受体将调节这些事件 直接在粗膜和纯化膜中进行研究。的影响 二酰甘油将与花生四烯酸上的佛波酯进行比较。 释放和磷脂酰胆碱代谢、细胞增殖和蛋白质 磷酸化。花生四烯酸在细胞内的潜在作用 将评估佛波醇酯和/或甘油二酯的中介物作用。 这些研究应该会加深我们对生物化学的理解。 佛波酯诱导花生四烯酸释放及其机制 磷脂酰胆碱代谢。此外，也是重要的是，这些 对佛波酯作用中近端细胞内事件的研究可能会有所帮助 阐明某些肿瘤发生发展的过程。

The proposed research involves defining proximal intracellular events involved in the action of tumor-promoting phorbol esters. Specifically, the biochemical mechanisms of arachidonic acid release and phosphatidylcholine metabolism will be investigated using GH3 rat pituitary cells. Although it has been suggested that stimulation of a phospholipase A2 and phospholipase C, respectively are causative in these events, conclusive evidence is lacking. These events are important because accumulated evidence from many cell types suggests 1) that arachidonic acid and/or metabolites may mediate tumor promotion and 2) phosphatidylcholine metabolism appears specifically related to phorbol ester action. GH3 cells provide an excellent model for these studies because 1) they are a homogeneous cell population permitting unambiguous assignment of changes to a specific cell type and 2) extensive research into protein kinase C, the putative phorbol ester receptor has been performed in these cells. Suggestions as to the enzymic reactions involved from intact cell studies will be confirmed in subcellular fractions. Whether protein kinase C or another cellular acceptor for phorbol esters mediates these events will be studied directly in crude and purified membranes. The effects of diacylglycerols will be compared to phorbol esters on arachidonic acid release and phosphatidylcholine metabolism, cell proliferation, and protein phosphorylation. A potential role for arachidonic acid as an intracellular mediator of phorbol ester and/or diacylglycerol action will be assessed. These studies should further our understanding of the biochemical mechanisms involved in phorbol ester-induced arachidonic acid release and phosphatidylcholine metabolism. Furthermore, and importantly, these studies into proximal intracellular events in phorbol ester action may help elucidate processes involved in the development of some neoplasias.