Phosphatidate accumulation in hormone-treated hepatocytes via a phospholipase D mechanism.
Phosphatidate accumulation in hormone-treated hepatocytes via a phospholipase D mechanism.
复制标题
DOI：
10.1016/s0021-9258(18)48176-8
复制
发表时间：
1987-11
期刊：
影响因子：
--
通讯作者：
S. Bocckino;P. Blackmore;P. Wilson;J. Exton
中科院分区：
文献类型：
--
作者：
S. Bocckino;P. Blackmore;P. Wilson;J. Exton
离体大鼠肝细胞响应各种钙动员剂（血管加压素，血管紧张素II，肾上腺素，表皮生长因子，ATP和ADP）与磷脂质量的快速增加，作为一个敏感的新方法测量。当肝细胞与加压素（10（-8）M）孵育时，磷脂酸水平在2分钟内增加2-3倍，但此时甘油二酯没有显著增加。磷脂酸的脂肪酸组成的变化也先于那些在二酰基甘油。从头合成的磷脂酸从[3 H]甘油不受加压素在短期孵育。孵育洗涤大鼠肝质膜与GTP γ S引起的磷脂酸的时间依赖性增加。当膜与GTP γ S和[γ-32 P]ATP孵育时，未观察到32 P掺入磷脂酸。这排除了磷脂酶C-二酰甘油激酶途径，并表明磷脂酶D活性产生的磷脂酸。在次最大浓度的GTP γ S，ATP和ADP刺激膜磷脂酸的形成，大概是通过P2-嘌呤能受体的作用。在主要磷脂中，只有磷脂酰胆碱在膜中响应GTP γ S而减少。在肝细胞中对血管加压素产生的磷脂酸的脂肪酸组成也表明磷脂酰胆碱可能是神经诱导的磷脂酸的来源。我们的结论是，钙动员激素主要增加肝细胞中的磷脂酸水平的机制，不涉及磷酸化的甘油二酯或从头合成，但涉及鸟嘌呤核苷酸结合蛋白耦合磷脂酶D。
Isolated rat hepatocytes responded to a variety of Ca2+-mobilizing agents (vasopressin, angiotensin II, epinephrine, epidermal growth factor, ATP, and ADP) with a rapid increase in phosphatidate mass, as measured by a sensitive new method. When hepatocytes were incubated with vasopressin (10(-8) M), phosphatidate levels increased 2-3-fold in 2 min, but there was no significant increase in diacylglycerol at this time. Changes in the fatty acid composition of phosphatidate also preceded those in diacylglycerol. De novo synthesis of phosphatidate from [3H]glycerol was unaffected by vasopressin in short-term incubation. Incubation of washed rat liver plasma membranes with GTP gamma S caused a time-dependent increase in phosphatidate. When membranes were incubated with GTP gamma S and [gamma-32P]ATP, no incorporation of 32P into phosphatidate was observed. This excludes the phospholipase C-diacylglycerol kinase pathway and suggests that a phospholipase D activity produced the phosphatidate. At submaximal concentrations of GTP gamma S, ATP and ADP stimulated membrane phosphatidate formation, presumably by acting through P2-purinergic receptors. Only phosphatidylcholine, among the major phospholipids, decreased in the membranes in response to GTP gamma S. The fatty acid composition of the phosphatidate produced in response to vasopressin in hepatocytes also suggests that phosphatidylcholine may be the source of hormonally elicited phosphatidate. We conclude that Ca2+-mobilizing hormones mainly increase phosphatidate levels in hepatocytes by a mechanism that does not involve phosphorylation of diacylglycerol or de novo synthesis but involves a guanine nucleotide-binding protein coupled to phospholipase D.