Cox L R, Murphy S K, Ramos K
Department of Pharmacology, Philadelphia College of Pharmacy and Science, Pennsylvania 19104.
Exp Mol Pathol. 1990 Aug;53(1):52-63. doi: 10.1016/0014-4800(90)90023-7.
Aortic smooth muscle cells (SMC) modulate from a contractile to a proliferative phenotype upon subchronic exposure to allylamine. The present studies were designed to determine if this phenotypic modulation is associated with alterations in the metabolism of membrane phosphoinositides. 32P incorporation into phosphatidylinositol 4-phosphate (PIP), phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidic acid (PA) was lower by 31, 35, and 22%, respectively, in SMC from allylamine-treated animals relative to controls. In contrast, incorporation of [3H]myoinositol into inositol phosphates did not differ in allylamine cells relative to control cells. Exposure to dibutyryl (db) cAMP (0.2 mM) and theophylline (0.1 mM) reduced 32P incorporation into PIP and PIP2 in SMC from both experimental groups. Under these conditions, a decrease in [3H]myoinositol incorporation into inositol 1-phosphate was only observed in allylamine cells. The effects of db cAMP and theophylline in allylamine and control SMC correlated with a marked decrease in cellular proliferation. These results suggest that alterations in phosphoinositide synthesis and/or degradation contribute to the enhanced proliferation of SMC induced by allylamine. To further examine this concept, the effects of agents which modulate protein kinase C (PKC) activity were evaluated. Sphingosine (125-500 ng/ml), a PKC inhibitor, decreased SMC proliferation in allylamine, but not control cells. 12-O-Tetradecanoylphorbol-13-acetate (1-100 ng/ml), a PKC agonist, stimulated proliferation in control cells, but inhibited proliferation in cells from allylamine-treated animals. We conclude that allylamine-induced phenotypic modulation of SMC is associated with alterations in phosphoinositide metabolism.
在亚慢性暴露于烯丙胺后，主动脉平滑肌细胞（SMC）会从收缩表型转变为增殖表型。本研究旨在确定这种表型调节是否与膜磷酸肌醇代谢的改变有关。与对照组相比，来自烯丙胺处理动物的SMC中，32P掺入磷脂酰肌醇4-磷酸（PIP）、磷脂酰肌醇4,5-二磷酸（PIP2）和磷脂酸（PA）的量分别降低了31%、35%和22%。相比之下，烯丙胺处理的细胞与对照细胞相比，[3H]肌醇掺入肌醇磷酸的量没有差异。暴露于二丁酰（db）cAMP（0.2 mM）和茶碱（0.1 mM）会降低两个实验组SMC中32P掺入PIP和PIP2的量。在这些条件下，仅在烯丙胺处理的细胞中观察到[3H]肌醇掺入肌醇1-磷酸的量减少。db cAMP和茶碱对烯丙胺处理和对照SMC的影响与细胞增殖的显著降低相关。这些结果表明，磷酸肌醇合成和/或降解的改变促成了烯丙胺诱导的SMC增殖增强。为了进一步研究这一概念，评估了调节蛋白激酶C（PKC）活性的药物的作用。PKC抑制剂鞘氨醇（125 - 500 ng/ml）可降低烯丙胺处理细胞而非对照细胞中的SMC增殖。PKC激动剂12-O-十四酰佛波醇-13-乙酸酯（1 - 100 ng/ml）可刺激对照细胞的增殖，但抑制烯丙胺处理动物细胞的增殖。我们得出结论，烯丙胺诱导的SMC表型调节与磷酸肌醇代谢的改变有关。
