Cook H W, Ridgway N D, Byers D M
Department of Pediatrics, Atlantic Research Centre, 5849 University Avenue, Dalhousie University, Halifax, NS, Canada
Biochim Biophys Acta. 1998 Feb 5;1390(1):103-17. doi: 10.1016/s0005-2760(97)00162-8.
Hydrolysis of phosphatidylcholine (PtdCho) can provide lipid second messengers involved in sustained signal transduction. Four neural-derived cell lines (C6 rat glioma; N1E-115 mouse and SK-N-MC and SK-N-SH human neuroblastoma) express different protein kinase C (PKC) isoforms and differentially respond to 4beta-12-O-tetradecanoylphorbol-13-acetate (beta-TPA)-stimulation of PtdCho synthesis. We examined involvement of PLD and PKC in the hydrolysis and resynthesis of PtdCho and phosphatidylethanolamine stimulated by beta-TPA, bryostatin (a non-phorbol PKC activator) and oleic acid (18:1n-9) in the four cell lines. beta-TPA or bryostatin produced similar enhancement of [3H]Cho incorporation, loss of stimulated synthesis after down regulation of PKC, and activation of PLD. In C6 cells, staurosporine (STS) and bis-indolylmaleimide (BIM) only partially inhibited basal and beta-TPA-stimulated PLD activity measured as choline or ethanolamine release; phosphatidylbutanol formation after prelabeling with [9,10-3H]18:1n-9, [9,10-3H]myristic acid (14:0), [1-14C]eicosapentaenoic acid (20:5n-3) or 1-O-[alkyl-1', 2-3H]-sn-glyceryl-3-phosphorylcholine gave similar results. STS at >200 nM activated PLD in the presence or absence of beta-TPA. In SK-N-SH cells where PtdCho synthesis was stimulated by beta-TPA or bryostatin, no effect of these agents on PLD was observed. 18:1n-9 stimulated PtdCho synthesis and, to a lesser extent, hydrolysis by PLD both with and without beta-TPA present. Fatty acids had no effect on PKC activities and down regulation of PKC with beta-TPA enhanced fatty acid stimulation of PtdCho synthesis. Thus, activation of PLD hydrolysis preceding resynthesis is involved in the stimulatory effects of beta-TPA on PtdCho synthesis in some but not all of these neural derived cells. Further, PLD hydrolysis of PtdCho and PtdEtn appear to have differing aspects of regulation. Fatty acid regulation of PtdCho synthesis occurs independent of PKC activation. Accordingly, regulation of membrane phospholipid degradation and resynthesis in association with lipid second messenger generation can involve a complex interplay of PLD, PKC, and fatty acids. (c) 1998 Elsevier Science B.V.
磷脂酰胆碱（PtdCho）的水解可产生参与持续信号转导的脂质第二信使。四种神经源性细胞系（C6大鼠胶质瘤细胞；N1E - 115小鼠神经母细胞瘤细胞以及SK - N - MC和SK - N - SH人神经母细胞瘤细胞）表达不同的蛋白激酶C（PKC）亚型，并且对4β - 12 - O - 十四酰佛波醇 - 13 - 乙酸酯（β - TPA）刺激的PtdCho合成有不同反应。我们研究了磷脂酶D（PLD）和PKC在β - TPA、苔藓抑素（一种非佛波醇PKC激活剂）和油酸（18:1n - 9）刺激下，这四种细胞系中PtdCho和磷脂酰乙醇胺的水解及再合成过程中的作用。β - TPA或苔藓抑素对[³H]胆碱掺入有类似的增强作用，PKC下调后刺激合成减少，且PLD被激活。在C6细胞中，星形孢菌素（STS）和双吲哚马来酰胺（BIM）仅部分抑制以胆碱或乙醇胺释放量衡量的基础及β - TPA刺激的PLD活性；用[9,10 - ³H]18:1n - 9、[9,10 - ³H]肉豆蔻酸（14:0）、[1 - ¹⁴C]二十碳五烯酸（20:5n - 3）或1 - O - [烷基 - 1', 2 - ³H] - sn - 甘油 - 3 - 磷酸胆碱预标记后形成磷脂丁醇，结果相似。在存在或不存在β - TPA的情况下，>200 nM的STS激活PLD。在SK - N - SH细胞中，β - TPA或苔藓抑素刺激PtdCho合成，但未观察到这些试剂对PLD有影响。无论有无β - TPA存在，18:1n - 9均刺激PtdCho合成，并在较小程度上刺激PLD水解。脂肪酸对PKC活性无影响，用β - TPA下调PKC可增强脂肪酸对PtdCho合成的刺激作用。因此，在再合成之前激活PLD水解参与了β - TPA对部分但并非所有这些神经源性细胞中PtdCho合成的刺激作用。此外，PLD对PtdCho和PtdEtn的水解似乎具有不同的调节方面。PtdCho合成的脂肪酸调节独立于PKC激活发生。因此，与脂质第二信使生成相关的膜磷脂降解和再合成的调节可能涉及PLD、PKC和脂肪酸之间的复杂相互作用。（c）1998爱思唯尔科学出版社B.V.
