The protein factor-arrest 11 (Far11) is essential for the toxicity of human caspase-10 in yeast and participates in the regulation of autophagy and the DNA damage signaling.

The heterologous expression of human caspase-10 in Saccharomyces cerevisiae induces a lethal phenotype, which includes some hallmarks of apoptosis and autophagy, alterations in the intra-S checkpoint, and cell death. To determine the cellular processes and pathways that are responsible of the caspase-10-induced cell death we have designed a loss-of-function screening system to identify genes that are essential for the lethal phenotype. We observed that the ER-Golgi-localized family of proteins Far, MAPK signaling, the autophagy machinery, and several kinases and phosphatases are essential for caspase-10 toxicity. We also found that the expression of caspase-10 elicits a simultaneous activation of the MAP kinases Fus3, Kss1, and Slt2. Furthermore, the protein Far11, which is a target of MAP kinases, is essential for the dephosphorylation of Atg13 and, consequently, for the induction of autophagy. In addition, Far11 participates in the regulation of the DNA damage response through the dephosphorylation of Rad53. Finally, we have also demonstrated that Far11 is able to physically interact with the phosphatases Pph21, Pph22, and Pph3. Overall, our results indicate that the expression of human caspase-10 in S. cerevisiae activates an intracellular death signal that depends on the Far protein complex and that Far11 may function as a regulator subunit of phosphatases in different processes, thus representing a mechanistic link between them.

Human initiator caspases trigger apoptotic and autophagic phenotypes in Saccharomyces cerevisiae.

Caspases are a family of proteases that participate in the progression and execution of the apoptotic program. However, regulation of the caspase activation and their substrates has not yet been fully elucidated. Here we explore the effect of the ectopic expression of the human initiator caspases-8 and -10 in Saccharomyces cerevisiae. Our results showed that the expression of human CASP10 and CASP8 triggers certain apoptotic markers such as a massive production of reactive oxygen species (ROS), chromatin condensation and phosphatidylserine externalization, finally leading to cell death. In response to hydroxyurea (HU), yeast cells expressing caspase-10 did not reduce the replication of DNA and escaped to the intra-S checkpoint of the cell cycle. In addition, caspase-10 expression induced yeast vacuolization and a vacuole-associated phenotype resembling autophagy. Other intracellular alterations such as disorganization of the actin cytoskeleton, cell wall damage, and aberrations within the endoplasmic reticulum lumen were also associated with caspase-10 expression. Furthermore, caspase-induced cell death was completely dependent on the proteolytic activation of the enzyme but, in contrast, was not dependent on either of the endogenous yeast apoptotic proteins Aif1 and Mca1 or the mitochondria.

The biological activity of the wine anthocyanins delphinidin and petunidin is mediated through Msn2 and Msn4 in Saccharomyces cerevisiae.

Polyphenols are considered to be responsible for some of the health benefits derived from the consumption of red wine. These protective effects might probably be explained in the context of the xenohormesis theory that considers plant metabolites as interspecific chemical signals. However, the complexity of the polyphenolic constituents of different wines makes it difficult to clarify the specific contribution of polyphenols to such effects. In the present work, we fractionated the polyphenols of a red wine and evaluated the effect of each polyphenolic fraction on the growth pattern of the yeast Saccharomyces cerevisiae. We observed a different contribution of the phenolic fractions to the xenohormetic response of S. cerevisiae, the fractions that were enriched with red pigments being the most protective against oxidative insults. Moreover, we found that red wine phenolic fractions exert their biological activity through the activation of the Yap1 and Msn2 stress-responsive regulators. Above all, the anthocyanins delphinidin 3-glucoside and petunidin 3-glucoside were found to improve significantly the growth rate of S. cerevisiae in an Msn2-, Msn4-dependent manner, indicating that the stress regulators Msn2 and Msn4 participate in the xenohormetic activity of the wine polyphenols delphinidin and petunidin.