Sphingoid bases and the serine catabolic enzyme CHA1 define a novel feedforward/feedback mechanism in the response to serine availability.

Targets of bioactive sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that sphingolipids may mediate the induction of Cha1 in response to serine availability.

Sphingolipids mediate formation of mRNA processing bodies during the heat-stress response of Saccharomyces cerevisiae.

Recent work, especially in the yeast Saccharomyces cerevisiae, has demonstrated that mRNA movement from active translation to cytoplasmic granules, termed mRNA'p-bodies' (processing bodies), occurs in concert with the regulation of translation during cell stress. However, the signals regulating p-body formation are poorly defined. Recent results have demonstrated a function for sphingolipids in regulating translation during heat stress, which led to the current hypothesis that p-bodies may form during heat stress in a sphingolipid-dependent manner.

ISC1-dependent metabolic adaptation reveals an indispensable role for mitochondria in induction of nuclear genes during the diauxic shift in Saccharomyces cerevisiae.

Growth of Saccharomyces cerevisiae following glucose depletion (the diauxic shift) depends on a profound metabolic adaptation accompanied by a global reprogramming of gene expression. In this study, we provide evidence for a heretofore unsuspected role for Isc1p in mediating this reprogramming. Initial studies revealed that yeast cells deleted in ISC1, the gene encoding inositol sphingolipid phospholipase C, which resides in mitochondria in the post-diauxic phase, showed defective aerobic respiration in the post-diauxic phase but retained normal intrinsic mitochondrial functions, including intact mitochondrial DNA, normal oxygen consumption, and normal mitochondrial polarization.

Roles for sphingolipid biosynthesis in mediation of specific programs of the heat stress response determined through gene expression profiling.

Previous studies have demonstrated roles for de novo production of sphingolipids in Saccharomyces cerevisiae in the regulation of the transient cell cycle arrest and nutrient permease degradation associated with the heat stress response, suggesting multiple functions for yeast sphingolipids in this response. We, therefore, sought to determine the generalized involvement of sphingolipids in the heat stress response by using microarray hybridization of RNA isolated from heat-stressed cultures of the mutant strain lcb1-100, which is unable to produce sphingolipids in response to heat. Approximately 70 genes showed differential regulation during the first 15 min of heat stress in the lcb1-100 strain compared with the wild type strain, indicating a requirement for de novo sphingolipid biosynthesis for proper regulation of these genes during heat stress.