A dual-function SNF2 protein drives chromatid resolution and nascent transcripts removal in mitosis.

Mitotic chromatin is largely assumed incompatible with transcription due to changes in the transcription machinery and chromosome architecture. However, the mechanisms of mitotic transcriptional inactivation and their interplay with chromosome assembly remain largely unknown. By monitoring ongoing transcription in Drosophila early embryos, we reveal that eviction of nascent mRNAs from mitotic chromatin occurs after substantial chromosome compaction and is not promoted by condensin I.

Polycomb group (PcG) proteins prevent the assembly of abnormal synaptonemal complex structures during meiosis.

The synaptonemal complex (SC) is a proteinaceous scaffold that is assembled between paired homologous chromosomes during the onset of meiosis. Timely expression of SC coding genes is essential for SC assembly and successful meiosis. However, SC components have an intrinsic tendency to self-organize into abnormal repetitive structures, which are not assembled between the paired homologs and whose formation is potentially deleterious for meiosis and gametogenesis.

NineTeen Complex-subunit Salsa is required for efficient splicing of a subset of introns and dorsal-ventral patterning.

The NineTeen Complex (NTC), also known as pre-mRNA-processing factor 19 (Prp19) complex, regulates distinct spliceosome conformational changes necessary for splicing. During midblastula transition, splicing is particularly sensitive to mutations in NTC-subunit Fandango, which suggests differential requirements of NTC during development. We show that NTC-subunit Salsa, the ortholog of human RNA helicase Aquarius, is rate-limiting for splicing of a subset of small first introns during oogenesis, including the first intron of Germline depletion of Salsa and splice site mutations within first intron impair both adult female fertility and oocyte dorsal-ventral patterning, due to an abnormal expression of Gurken.

Absence of the Spindle Assembly Checkpoint Restores Mitotic Fidelity upon Loss of Sister Chromatid Cohesion.

The fidelity of mitosis depends on cohesive forces that keep sister chromatids together. This is mediated by cohesin that embraces sister chromatid fibers from the time of their replication until the subsequent mitosis [1-3]. Cleavage of cohesin marks anaphase onset, where single chromatids are dragged to the poles by the mitotic spindle [4-6].

N-terminal acetylation modulates Bax targeting to mitochondria.

The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity.

Naa50/San-dependent N-terminal acetylation of Scc1 is potentially important for sister chromatid cohesion.

The gene separation anxiety (san) encodes Naa50/San, a N-terminal acetyltransferase required for chromosome segregation during mitosis. Although highly conserved among higher eukaryotes, the mitotic function of this enzyme is still poorly understood. Naa50/San was originally proposed to be required for centromeric sister chromatid cohesion in Drosophila and human cells, yet, more recently, it was also suggested to be a negative regulator of microtubule polymerization through internal acetylation of beta Tubulin.

Developmental roles of protein N-terminal acetylation.

Discovered more than 50 years ago, N-terminal acetylation (N-Ac) is one of the most common protein modifications. Catalyzed by different N-terminal acetyltransferases (NATs), N-Ac was originally believed to mostly promote protein stability. However, several functional consequences at substrate level were recently described that yielded important new insights about the distinct molecular functions for this modification.

Flow cytometry as a novel tool for structural and functional characterization of isolated yeast vacuoles.

The yeast vacuole is functionally analogous to the mammalian lysosome. Both play important roles in fundamental cellular processes such as protein degradation, detoxification, osmoregulation, autophagy and apoptosis which, when deregulated in humans, can lead to several diseases. Some of these vacuolar roles are difficult to study in a cellular context, and therefore the use of a cell-free system is an important approach to gain further insight into the different molecular mechanisms required for vacuolar function.

Yeast as a powerful model system for the study of apoptosis regulation by protein kinase C isoforms.

Protein kinase C (PKC) is a family of serine/threonine kinases involved in the transduction of signals that control different cellular processes, such as cell death and proliferation. This family comprises at least 10 isoforms that regulate apoptosis in an isoformspecific manner. However, controversial data about the role of individual PKC isoforms in apoptosis regulation are frequently reported.

The importance of humanized yeast to better understand the role of bcl-2 family in apoptosis: finding of novel therapeutic opportunities.

The Bcl-2 protein family plays a central role in mitochondrial membrane permeabilization. This event and the ensuing release of cytochrome c are decisive in the apoptotic cascade. Therefore, a better knowledge of these processes and their regulation will probably lead to the development of novel therapeutic strategies for treatment of apoptosis-related diseases.

Modulation of Bax mitochondrial insertion and induced cell death in yeast by mammalian protein kinase Cα.

Protein kinase Cα (PKCα) is a classical PKC isoform whose involvement in cell death is not completely understood. Bax, a major member of the Bcl-2 family, is required for apoptotic cell death and regulation of Bax translocation and insertion into the outer mitochondrial membrane is crucial for regulation of the apoptotic process. Here we show that PKCα increases the translocation and insertion of Bax c-myc (an active form of Bax) into the outer membrane of yeast mitochondria.

The impact of acetate metabolism on yeast fermentative performance and wine quality: reduction of volatile acidity of grape musts and wines.

Acetic acid is the main component of the volatile acidity of grape musts and wines. It can be formed as a by-product of alcoholic fermentation or as a product of the metabolism of acetic and lactic acid bacteria, which can metabolize residual sugars to increase volatile acidity. Acetic acid has a negative impact on yeast fermentative performance and affects the quality of certain types of wine when present above a given concentration.

Isc1p plays a key role in hydrogen peroxide resistance and chronological lifespan through modulation of iron levels and apoptosis.

The inositolphosphosphingolipid phospholipase C (Isc1p) of Saccharomyces cerevisiae belongs to the family of neutral sphingomyelinases that generates the bioactive sphingolipid ceramide. In this work the role of Isc1p in oxidative stress resistance and chronological lifespan was investigated. Loss of Isc1p resulted in a higher sensitivity to hydrogen peroxide that was associated with an increase in oxidative stress markers, namely intracellular oxidation, protein carbonylation, and lipid peroxidation.

Specific modulation of apoptosis and Bcl-xL phosphorylation in yeast by distinct mammalian protein kinase C isoforms.

Mammalian protein kinase C (PKC) isoforms have been subject of particular attention because of their ability to modulate apoptotic proteins. However, the roles played by each PKC isoform in apoptosis are still unclear. Here, expression of individual mammalian PKC isoforms in Saccharomyces cerevisiae is used as a new approach to study the role of each isoform in apoptosis.

Hyperosmotic stress induces metacaspase- and mitochondria-dependent apoptosis in Saccharomyces cerevisiae.

During the last years, several reports described an apoptosis-like programmed cell death process in yeast in response to different environmental aggressions. Here, evidence is presented that hyperosmotic stress caused by high glucose or sorbitol concentrations in culture medium induces in Saccharomyces cerevisiae a cell death process accompanied by morphological and biochemical indicators of apoptotic programmed cell death, namely chromatin condensation along the nuclear envelope, mitochondrial swelling and reduction of cristae number, production of reactive oxygen species and DNA strand breaks, with maintenance of plasma membrane integrity. Disruption of AIF1 had no effect on cell survival, but lack of Yca1p drastically reduced metacaspase activation and decreased cell death indicating that this death process was associated to activation of this protease.