In S. cerevisiae, sphingolipids are mainly located in the plasma membrane, being more concentrated along the sphingolipid-sterol rich domains [24], commonly named rafts. These domains play fundamental roles in connecting the plasma membrane to the cytoskeleton, ER and Golgi, and therefore in the correct protein Tanespimycin cost sorting and trafficking through exocytosis/endocytosis [25]. Moreover, rafts harbour signalling molecules besides sphingolipids, like kinases, PI2P (phosphatidylinositol-3,4-diphosphate), and GPI (glycosylphosphatidylinositol)-anchored proteins [25, 26]. The latter, are proteins attached to the plasma membrane via a lipid anchor that contains

either a ceramide or diacylglycerol [27]. Gup1p is a membrane-bound O-acyltransferase [28, 29] involved in lipid metabolism, rafts integrity and assembly [30] and GPI anchor remodelling [31]. This protein was primarily identified associated with phenotypes on glycerol metabolism and transport [32], but has further been implicated in a vast number of distinct processes, namely cell wall structure, composition and biogenesis [33], plasma membrane assembly and composition [30, 34], cytoskeleton polarization and bud site selection [35], and telomere length [36], all of which directly or indirectly associated with apoptosis. This work

presents evidence that cells lacking GUP1 are not able of undergoing apoptosis, as revealed by the analysis of several apoptotic markers (mainly lack of membrane integrity and of phosphatidylserine externalization). Instead STI571 datasheet the mutant appears to be experiencing a necrotic cell death process, upon both CH5183284 molecular weight chronological aging and acetic acid induction. This result adds to the

growing view that as in higher eukaryotes, lipids are involved in Morin Hydrate signalling PCD in yeast. Results GUP1 is involved in a wide range of cellular processes, some of which are associated directly or indirectly with apoptosis, such as rafts integrity and lipids metabolism [17, 18, 21, 30, 31, 34], cytoskeleton polarization [35, 37], and telomere length [36, 38]. In the present work, we assess apoptotic markers for gup1∆ mutant strain and compare them with Wt, under two different conditions documented to induce apoptosis in yeast: chronological aging and acetic acid [8, 39]. gup1∆ mutant cells exhibit a reduction in chronological lifespan Yeast chronological lifespan is described as the length of time a population remains viable in the non-dividing/stationary phase [40, 41]. Chronologically aged yeast cells die exhibiting specific markers of apoptosis [6, 40]. We checked the survival of gup1∆ chronologically aged cells in comparison to Wt, continuously for 30 days throughout stationary phase until complete death of the culture. The growth curve (Figure 1 insert) showed an apparent similar growth rate for both strains during exponential phase, as well as an almost coincident transition to diauxic and stationary phases.