TheDPL1Gene Is Involved in Mediating the Response to Nutrient Deprivation inSaccharomyces cerevisiae

Sphingosine-1-phosphate is a sphingolipid metabolite involved in the regulation of cell proliferation in mammalian cells. The major route of sphingosine-1-phosphate degradation is through cleavage at the C_2–3bond by sphingosine phosphate lyase. The recent identification of the first dihydrosphingosine/sphingosine phosphate lyase gene inSaccharomyces cerevisiaeestablishes that phosphorylated sphingoid base metabolism is conserved throughout evolution. Thedpl1Δ deletion mutant, which accumulates endogenous phosphorylated sphingoid bases, exhibits unregulated proliferation upon approach to stationary phase. The increased proliferation rate during respiratory growth was associated with failure to appropriately recruit cells into the G₁phase of the cell cycle. Several genes were found to be overexpressed or prematurely expressed during nutrient deprivation in thedpl1Δ strain, including glucose-repressible genes and G₁cyclins. These studies implicate a role forDPL1and phosphorylated sphingoid bases in the regulation of global responses to nutrient deprivation in yeast.