RELATIONSHIP OF BILE-SALT STIMULATION OF COLONIC EPITHELIAL PHOSPHOLIPID TURNOVER AND PROLIFERATIVE ACTIVITY - ROLE OF ACTIVATION OF PROTEIN-KINASE-C
RELATIONSHIP OF BILE-SALT STIMULATION OF COLONIC EPITHELIAL PHOSPHOLIPID TURNOVER AND PROLIFERATIVE ACTIVITY - ROLE OF ACTIVATION OF PROTEIN-KINASE-C
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DOI：
10.1016/0091-7435(87)90074-0
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发表时间：
1987-07-01
影响因子：
5.1
通讯作者：
CRAVEN, PA
中科院分区：
文献类型：
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作者：
DERUBERTIS, FR;CRAVEN, PA
胆汁盐刺激结肠上皮增殖活性的机制尚不清楚。某些增强结肠上皮增殖活性的胆汁盐（例如脱氧胆酸盐（DOC）和鹅脱氧胆酸盐）的显着细胞作用之一是快速刺激膜磷脂周转。膜磷酸肌醇周转增加可能导致二酰基甘油 (DAG) 的释放。后者是钙磷脂依赖性酶蛋白激酶 C (PKC) 的内源性激活剂，其刺激与多种细胞系统的增殖增强相关。在本研究中，我们在体外和体内检查了 DOC 对结肠上皮 PKC 的影响。当直接在体外添加到从大鼠结肠分离的隐窝中提取的磷脂、钙依赖性 PKC 的部分纯化可溶性制剂中时，DOC 抑制了 20% 的活性，这可能是由于钙复合物的形成。相比之下，肿瘤促进剂12-O-十四烷酰佛波醇-13-乙酸酯(TPA)和DAG衍生物1-油酰基-2-乙酰甘油(OAG)在体外使可溶性PKC增加两倍。非肿瘤启动子佛波醇和4α-佛波醇-12,13-二癸酸酯（4αPDD）没有效果。然而，在用花生四烯酸预标记的完整结肠上皮隐窝细胞中，DOC 导致 DAG 快速释放，并显着增加与颗粒细胞分数相关的 PKC 分数，这是 PKC 激活的指数。 TPA 和 OAG 引起 PKC 亚细胞分布的类似变化，但不刺激 DAG 释放，而佛波醇和 4αPDD 对任何参数都没有影响。 DOC、OAG 或 TPA 体内结肠内滴注均诱导可溶性 PKC 向结肠粘膜刮屑的颗粒部分转移。后者体内 PKC 的变化与结肠粘膜鸟氨酸脱羧酶活性的增加和 [3H]dThd 掺入 DNA 相关。佛波醇和 4αPDD 未能在体内改变任何这些参数。结果支持 PKC 激活在胆盐刺激结肠上皮增殖活性中的作用。
The mechanism by which bile salts stimulate the proliferative activity of colonic epithelium is uncertain. One of the striking cellular actions of certain bile salts that enhance the proliferative activity of colonic epithelium, such as deoxycholate (DOC) and chenodeoxycholate, is the rapid stimulation of membrane phospholipid turnover. Increased membrane phosphoinositol turnover may lead to release of diacylglycerol (DAG). The latter is an endogenous activator of the calcium phospholipid-dependent enzyme protein kinase C (PKC) whose stimulation has been correlated with enhanced proliferation in several cell systems. In the present study, we examined the effects of DOC on PKC of colonic epitheliumin vitroandin vivo. When added directlyin vitroto partially purified soluble preparations of phospholipid, calcium-dependent PKC from crypts isolated from rat colon, DOC suppressed activity by 20%, presumably due to calcium complex formation. By contrast, the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), and the DAG derivative, 1-oleoyl-2-acetylglycerol (OAG), increased soluble PKCin vitrotwofold. The nontumor promoters phorbol and 4α-phorbol-12,13-didecanoate (4αPDD) were without effect. However, in intact colonic epithelial crypt cells prelabeled with arachidonate, DOC caused rapid release of DAG and markedly increased the fraction of PKC associated with the particulate cell fraction, an index of PKC activation. TPA and OAG caused similar shifts in the subcellular distribution of PKC but did not stimulate DAG release, whereas phorbol and 4αPDD were without effect on any parameter.In vivointracolonic instillation of DOC, OAG, or TPA each induced a shift of soluble PKC to the particulate fraction of colonic mucosal scrapings. The latterin vivochanges in PKC were associated with increases in colonic mucosal ornithine decarboxylase activity and [3H]dThd incorporation into DNA. Phorbol and 4αPDD failed to alter any of these parametersin vivo. The results support a role for activation of PKC in bile salt stimulation of colonic epithelial proliferative activity.