Induction of stearoyl-CoA desaturase 2 gene expression correlates with fatty acid changes in phosphatidylcholine

Chronic exposure of BW5147 cells to arachidonic acid results in a complete inhibition of stearoyl-CoA desaturase 2 gene expression. Following removal of the fatty acid, gene transcription increased with a kinetic profile similar to the observed increases in both stearoyl-CoA desaturase 2 mRNA and unsaturated fatty acid synthesis. During the time period when stearoyl-CoA desaturase 2 transcription and unsaturated fatty acid synthesis increased (6-12 h), there was only a minimal depletion (approximately 2%) of the total phospholipid arachidonic acid-content. By contrast, during the same period there was a specific depletion of arachidonic acid from phosphatidylcholine, but the proportion of arachidonic acid in other phospholipid species did not change. Thus, changes in the fatty acid content of phosphatidylcholine may be of particular importance in the genetic regulation of endogenous lipid synthesis.