Arachidonic Acid Incorporation and Redistribution in Human Neuroblastoma (SK‐N‐BE) Cell Phospholipids

Abstract

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.

Selective Effect of a Diet-Induced Decrease in the Arachidonic Acid Membrane-Phospholipid Content on in vitro Phospholipase C and Adenylate Cyclase-Mediated Pituitary Response to Angiotensin II

“…The fatty acid is indeed most strongly decreased in ChoPG, a finding also reported in other tis sues [37], This is consistent with recent data suggesting initial acylation of the 2-lyso-ChoPG molecule by polyun saturated fatty acids. Subsequent transfers of these fatty acids to other phosphoglyceride classes are assumed to result from selective deacylation/reacylation processes [38][39][40][41] On the other hand, preferential conservation of AA InsPG content in AA in spite of the metabolically active nature of InsPG could be related to the importance of AA containing InsPG for transduction processes. It also sug gests preferential PLC-generated DAG rephosphorylation by the DAG kinase and low DAG lipase activity in pitu itary membranes.…”

Muscarinic stimulation of SK-N-BE(2) human neuroblastoma cells elicits phosphoinositide and phosphatidylcholine hydrolysis: relationship to diacylglycerol and phosphatidic acid accumulation

“…Two-dimensional separation of phospholipids was carried out on high-performance t.l.c. plates as described [16]. Neutral lipids and free fatty acids were separated on high-performance t.l.c.…”