Arginine vasopressin stimulates phospholipid methylation in cultured rat mesangial cells: possible role for PGE 2 production

Abstract

Incorporation of [ 3H-methyl] groups into phospholipids and prostaglandin E 2 (PGE 2) production in cultured rat mesangial cells were examined in the presence and absence of arginine vasopressin (AVP). In cells stimulated with AVP, a rapid increase in the incorporation of [ 3H-methyl] group into phospholipids was observed within 1 min after stimulation. The [ 3H-methyl] group present in the phospholipids began to decline 2.5 min after stimulation. The production of PGE 2 increased with AVP treatment, and the decline in methylated phospholipids paralleled the release of PGE 2 in AVP-stimulated cells. The inhibition of phospholipid methylation by treatment with adenosyl-S-isobutyl mercaptan (SIBA) resulted in a marked decrease in AVP-stimulated PGE 2 production. In order to determine the identity of the methylated phospholipids, [ 3H-methyl] incorporation into phosphatidylethanolamine derivatives was examined. In AVP-stimulated cells, an increase of [ 3H-methyl] labeled phosphatidylcholine and lysophosphatidylcholine was observed after stimulation with AVP, followed by an apparent increase of [ 3H-methyl] labeled lysophosphatidylcholine. These findings indicate that AVP stimulates phospholipid methylation in cultured rat mesangial cells and phosphatidylcholine, synthesized by a transmethylation pathway, may be a source for PGE 2 production.