Hermans S W, Engelmann B, Reinhardt U, Bartholomeus-Van Nooij I G, De Pont J J, Willems P H
Department of Biochemistry, University of Nijmegen, The Netherlands.
Eur J Biochem. 1996 Jan 15;235(1-2):73-81. doi: 10.1111/j.1432-1033.1996.00073.x.
The aim of the present study was to assess the origin of the 1,2-diradylglycerols produced during prolonged hormonal stimulation of rabbit pancreatic acini by comparison of their relative molecular species composition with that of the major acinar phospholipids. Both phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) consisted of 1,2-diacyl as well as 1-alk-1-2-acyl species. In contrast, phosphatidylinositol (PtdIns), phosphatidylserine and phosphatidic acid existed only in the 1,2-diacyl form. Acinar cells did not contain detectable amounts of 1-alkyl-2-acyl phospholipids. Similarly, the acinar 1,2-diradylglycerol fraction consisted of 1,2-diacylglycerols and 1-alk-1-enyl-2-acylglycerols. Mass 1,2-diradylglycerol measurements revealed that prolonged stimulation with cholecystokinin resulted in a marked and sustained increase in acinar 1,2-diradylglycerol content. Based on the relative amounts of the 1,2-diacyl species present in both the 1,2-diradylglycerol fraction and the individual phospholipids, it is calculated that under control conditions 60% of the 1,2-diacylglycerols originate from PtdCho and 40% from PtdIns, whereas under stimulatory conditions 53% is calculated to be derived from PtdCho, 46% from PtdIns and 1% from PtdEtn. Likewise, it is calculated that in control as well as stimulated acini 100% of the 1-alk-l-enyl-2-acylglycerols originate from plasmenylcholine. Further evidence in favour of the idea that at least a considerable part of the 1,2-diacylglycerols produced during prolonged hormonal stimulation originate from inositolphospholipids is provided by the observation that labeling of phosphatidylinositol 4,5-bisphosphate with inorganic phosphate reached isotopic equilibrium markedly faster under stimulatory conditions as compared to the control situation, which is in agreement with an elevated turnover rate. The data presented support the idea that PtdCho and inositolphospholipids are the major precursors in basal and stimulated 1,2-diradylglycerol production in rabbit pancreatic acini.
本研究的目的是通过比较兔胰腺腺泡在长时间激素刺激过程中产生的1,2 - 二酰基甘油的相对分子种类组成与主要腺泡磷脂的相对分子种类组成，来评估其来源。磷脂酰胆碱（PtdCho）和磷脂酰乙醇胺（PtdEtn）均由1,2 - 二酰基以及1 - 烷基 - 1 - 烯基 - 2 - 酰基种类组成。相比之下，磷脂酰肌醇（PtdIns）、磷脂酰丝氨酸和磷脂酸仅以1,2 - 二酰基形式存在。腺泡细胞中未检测到可检测量的1 - 烷基 - 2 - 酰基磷脂。同样，腺泡1,2 - 二酰基甘油部分由1,2 - 二酰基甘油和1 - 烷基 - 1 - 烯基 - 2 - 酰基甘油组成。1,2 - 二酰基甘油的质量测量显示，用胆囊收缩素进行长时间刺激会导致腺泡1,2 - 二酰基甘油含量显著且持续增加。根据1,2 - 二酰基甘油部分和各个磷脂中存在的1,2 - 二酰基种类的相对量计算得出，在对照条件下，60%的1,2 - 二酰基甘油源自PtdCho，40%源自PtdIns，而在刺激条件下，计算得出53%源自PtdCho，46%源自PtdIns，1%源自PtdEtn。同样，计算得出在对照和刺激的腺泡中，100%的1 - 烷基 - 1 - 烯基 - 2 - 酰基甘油源自缩醛磷脂酰胆碱。与对照情况相比，在刺激条件下用无机磷酸盐标记磷脂酰肌醇4,5 - 二磷酸达到同位素平衡的速度明显更快，这一观察结果为长时间激素刺激过程中产生的至少相当一部分1,2 - 二酰基甘油源自肌醇磷脂这一观点提供了进一步的证据，这与周转率升高一致。所呈现的数据支持了PtdCho和肌醇磷脂是兔胰腺腺泡基础和刺激状态下1,2 - 二酰基甘油产生的主要前体这一观点。
