Ceramides modulate protein kinase C activity and perturb the structure of phosphatidylcholine/phosphatidylserine bilayers
Ceramides modulate protein kinase C activity and perturb the structure of phosphatidylcholine/phosphatidylserine bilayers
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DOI：
10.1016/s0006-3495(99)76996-1
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发表时间：
1999-09-01
影响因子：
3.4
通讯作者：
Zidovetzki, R
中科院分区：
文献类型：
--
作者：
Huang, HW;Goldberg, EM;Zidovetzki, R
在7.5 mol %二油碱（DO）不存在或不存在的情况下，采用H-2-NMR和特异性酶法研究了天然神经酰胺和一系列不同酰基链长的神经酰胺类似物对大鼠脑蛋白激酶C （PKC）活性和牛肝磷脂酰胆碱(BLPC)/二棕榈酰磷脂酰胆碱(DPPC)/二棕榈酰磷脂酰丝氨酸（DPPS）（3:1:1摩尔比）双层结构的影响。在加入短链神经酰胺类似物（C-2-、C-6-或c -8神经酰胺）后，PKC仅被轻微激活；天然神经酰胺或c -16神经酰胺没有效果。在7.5 mol % DO的存在下，天然神经酰胺和c -16神经酰胺类似物轻微减弱DO增强的PKC活性。H-2-NMR结果表明，天然神经酰胺和c -16-神经酰胺诱导了双分子层中凝胶和液晶畴的侧向相分离；然而，这种类型的膜扰动对PKC活性没有直接影响。短链神经酰胺类似物和DO的加入对PKC具有协同激活作用，当c -6-神经酰胺和DO分别为20 mol %和15 mol %时，活性最大。c -6神经酰胺和/或DO浓度的进一步增加导致PKC活性降低。详细的H-2-NMR研究了c -6-神经酰胺和DO对脂质双分子层结构的联合作用，发现这两种试剂的协同作用增加了膜采用非双分子层结构的倾向，导致在超过20 mol %神经酰胺和15 mol % DO的样品中实际存在这种结构。因此，形成非双层脂相的趋势增加与PKC活性增加相关，而这些相的实际存在降低了酶的活性。此外，研究结果表明，被广泛用于神经酰胺细胞效应研究的短链神经酰胺类似物具有天然神经酰胺所不具备的生物学效应。
We studied the effects of natural ceramide and a series of ceramide analogs with different acyl chain lengths on the activity of rat brain protein kinase C (PKC) and on the structure of bovine liver phosphatidylcholine (BLPC)/dipalmitoylphosphatidylcholine (DPPC)/dipalmitoylphosphatidylserine (DPPS) (3:1:1 molar ratio) bilayers using H-2-NMR and specific enzymatic assays in the absence or presence of 7.5 mol % diolein (DO). Only a slight activation of PKC was observed upon addition of the short-chain ceramide analogs (C-2-, C-6-, or C-8-ceramide); natural ceramide or C-16-ceramide had no effect. In the presence of 7.5 mol % DO, natural ceramide and C-16-ceramide analog slightly attenuated DO-enhanced PKC activity. H-2-NMR results demonstrated that natural ceramide and C-16-ceramide induced lateral phase separation of gel-like and liquid crystalline domains in the bilayers; however, this type of membrane perturbation has no direct effect on PKC activity. The addition of both short-chain ceramide analogs and DO had a synergistic effect in activating PKC, with maximum activity observed with 20 mol % C-6-ceramide and 15 mot % DO. Further increases in C-6-ceramide and/or DO concentrations led to decreased PKC activity. A detailed H-2-NMR investigation of the combined effects of C-6-ceramide and DO on lipid bilayer structure showed a synergistic effect of these two reagents to increase membrane tendency to adopt nonbilayer structures, resulting in the actual presence of such structures in samples exceeding 20 mol % ceramide and 15 mol % DO. Thus, the increased tendency to form nonbilayer lipid phases correlates with increased PKC activity, whereas the actual presence of such phases reduced the activity of the enzyme. Moreover, the results show that short-chain ceramide analogs, widely used to study cellular effects of ceramide, have biological effects that are not exhibited by natural ceramide.