Spinedi A, Pacini L, Piacentini M, Melino G, Luly P
Department of Biology, University of Rome Tor Vergata, Italy.
J Neurochem. 1990 Mar;54(3):778-82. doi: 10.1111/j.1471-4159.1990.tb02318.x.
The incorporation and redistribution of [1-14C]arachidonic acid in SK-N-BE human neuroblastoma cell phospholipids were investigated. By continuous labelling in serum-enriched medium, a rapid radioactivity incorporation into phosphatidylcholine (PtdCho), phosphatidylinositol, and phosphatidylserine was observed; initially, phosphatidylethanolamine (PtdEtn) was poorly labelled, but at later stages it displayed the highest level of arachidonic acid incorporation, in comparison with other phospholipid classes. Labelling of triacylglycerols was also observed. When cells were pulse-labelled with [1-14C]arachidonic acid and then reincubated in label-free medium, a decrease of the radioactivity in triacylglycerols was observed initially, paralleled by an increase of phospholipid labelling; thereafter, arachidonic acid redistribution was consistent with a net decrease of the radioactivity associated with PtdCho acid-stable forms (i.e., diacyl plus alkylacyl forms), concomitantly with a net labelling increase of both acid-stable PtdEtn and alkenylacyl-PtdEtn. Data indicate the following: (a) neuroblastoma cells incorporate arachidonic acid into phospholipids through complex kinetics involving transfer of the fatty acid from acid-stable PtdCho to both alkenylacyl-PtdEtn and acid-stable PtdEtn; and (b) triacylglycerols act as storage molecules for arachidonic acid which is subsequently incorporated into phospholipids. The possibility that arachidonic acid transfer to PtdEtn subclasses is driven by distinct mechanisms is discussed.
研究了[1-14C]花生四烯酸在SK-N-BE人神经母细胞瘤细胞磷脂中的掺入和重新分布情况。通过在富含血清的培养基中连续标记，观察到放射性迅速掺入磷脂酰胆碱（PtdCho）、磷脂酰肌醇和磷脂酰丝氨酸中；最初，磷脂酰乙醇胺（PtdEtn）标记较差，但在后期，与其他磷脂类别相比，它显示出最高水平的花生四烯酸掺入。还观察到三酰甘油的标记。当用[1-14C]花生四烯酸对细胞进行脉冲标记，然后在无标记培养基中再孵育时，最初观察到三酰甘油中的放射性降低，同时磷脂标记增加；此后，花生四烯酸的重新分布与与PtdCho酸稳定形式（即二酰基加烷基酰基形式）相关的放射性净减少一致，同时酸稳定的PtdEtn和烯基酰基-PtdEtn的净标记增加。数据表明：（a）神经母细胞瘤细胞通过复杂的动力学将花生四烯酸掺入磷脂中，该动力学涉及脂肪酸从酸稳定的PtdCho转移到烯基酰基-PtdEtn和酸稳定的PtdEtn；（b）三酰甘油作为花生四烯酸的储存分子，随后被掺入磷脂中。讨论了花生四烯酸转移到PtdEtn亚类是由不同机制驱动的可能性。
