Three activators of protein kinase C, bryostatins, dioleins, and phorbol esters, show differing specificities of action on GH4 pituitary cells.
Three activators of protein kinase C, bryostatins, dioleins, and phorbol esters, show differing specificities of action on GH4 pituitary cells.
复制标题
DOI：
10.1016/s0021-9258(19)76001-3
复制
发表时间：
1986-12
期刊：
影响因子：
--
通讯作者：
J. Ramsdell;G. Pettit;A. Tashjian
中科院分区：
文献类型：
--
作者：
J. Ramsdell;G. Pettit;A. Tashjian
佛波酯类肿瘤促进剂如12-O-十四酰佛波酯(TPA)可激活钙和磷脂依赖的蛋白激酶C，增强GH4C5大鼠垂体细胞的三种生物学反应(催乳素释放、催乳素合成和细胞伸展)。我们研究了从海洋苔藓虫Bugula neritina分离的TPA和另外两类蛋白激酶C激活剂对GH4C5细胞的几种作用，这两种激活剂是人工合成的细胞双脂素和苔藓抑素。在完整细胞中，Bryostatins 1和2(分别为B1和B2)与TPA竞争结合蛋白激酶C复合体的[~3H]佛波醇12，13-二丁酸酯。B1和B2，1-油酰基-2-乙酰甘油(OAG)和1，2-二辛酰甘油(Di8)以及TPA分别激活部分纯化的GH4C5细胞的蛋白激酶C。B1、B2和TPA分别以相似的最大程度促进GH4C5细胞催乳素的急性释放。B1、B2和TPA也促进了催乳素的合成。然而，B1和B2只是部分激动剂，因为它们促进催乳素合成的最大程度低于TPA，并且联合使用时，它们减少了TPA促进的催乳素合成。OAG和Di8刺激催乳素的释放(幅度小于TPA)，但不刺激催乳素的合成。OAG预处理并不减少TPA刺激的催乳素的释放或合成。B2和TPA诱导GH4C5细胞伸展，而B1、OAG和Di8几乎不引起伸展。与TPA联合给药的B1，但不能拮抗TPA诱导的拉伸，但不能减少促甲状腺激素释放激素或表皮生长因子诱导的拉伸。我们得出结论，苔藓他汀类、佛波醇酯和甘油酯结合到蛋白激酶C复合体上的同一位置以激活酶，但它们改变了GH4C5细胞中的三种生物反应，具有不同的选择性和有效性。我们认为，不同的蛋白激酶C激活剂(如苔藓他汀类、甘油酯和佛波酯)可能通过改变底物特异性或激活多种形式的激酶而引起不同的细胞反应。
Phorbol ester tumor promoters such as 12-O-tetradecanoylphorbol acetate (TPA) activate the calcium- and phospholipid-dependent protein kinase C and enhance three biological responses (prolactin release, prolactin synthesis, and cell stretching) in GH4C5 rat pituitary cells. We have examined several actions on GH4C5 cells of TPA and two other classes of protein kinase C activators, synthetic cell permeant dioleins and bryostatins isolated from the marine bryozoan Bugula neritina. Bryostatins 1 and 2 (B1 and B2, respectively) competed for [3H]phorbol 12,13-dibutyrate binding to the protein kinase C complex in intact cells nearly equipotently with TPA. B1 and B2, 1-oleoyl-2-acetylglycerol (OAG) and 1,2-dioctanoylglycerol (Di8) as well as TPA each activated partially purified protein kinase C from GH4C5 cells. B1, B2, and TPA each enhanced the acute release of prolactin from GH4C5 cells to a similar maximal extent. B1, B2, and TPA also enhanced prolactin synthesis. However, B1 and B2 were only partial agonists because they enhanced prolactin synthesis to a lesser maximal extent than did TPA and, given in combination, they reduced TPA-enhanced prolactin synthesis. OAG and Di8 stimulated prolactin release (to a lesser maximal extent than TPA) and did not stimulate prolactin synthesis. Pretreatment with OAG did not reduce TPA-stimulated prolactin release or synthesis. B2 and TPA induced cell stretching in GH4C5 cells, whereas B1, OAG, and Di8 induced little if any stretching. B1, but not B2, given in combination with TPA antagonized TPA-induced stretching but did not reduce thyrotropin-releasing hormone- or epidermal growth factor-induced stretching. We conclude that the bryostatins, phorbol esters, and dioleins bind to the same site on the protein kinase C complex to activate the enzyme, but they alter three biological responses in GH4C5 cells with selectivities and efficacies that differ. We propose that different activators of protein kinase C (such as bryostatins, dioleins, and phorbol esters) may elicit different cellular responses by altering the substrate specificity or activating multiple forms of the kinase.