The Role of Phospholipid Synthesis in Lipid‐mediated Signaling and Regulation in Yeast

Rapid genome‐wide changes in the transcription of hundreds of genes in yeast cells occur in response to changes in lipid metabolism that accompany the provision of inositol, the immediate precursor to phosphatidylinositol (1, 2). Changes in the synthesis and turnover of lipids that accompany these transcriptional responses include decreases in phosphatidic acid and CDP‐diacylglycerol and an increase in the rate of phosphatidylinositol synthesis and phosphatidylcholine turnover (3, 4). These changes in the patterns of synthesis or turnover of these lipids influence several major signaling pathways and transcriptional networks. Moreover, the Protein Kinase C pathway is involved in maintaining lipid homeostasis in cells deprived of inositol when choline is present. A screen of viable gene deletion mutants for phenotypes associated with misregulation of lipid metabolism identified many mutants defective in several major stress response pathways. We will discuss the roles of these signaling pathways in cellular homeostasis under conditions of changing lipid metabolism.This work is supported by NIH grant GM‐19629.