Research, Research Articles
The lysosomotropic drug LeuLeu-OMe induces lysosome disruption and autophagy-independent cell death in Trypanosoma brucei
Hazel Xinyu Koh1,2, Htay Mon Aye1, Kevin S. W. Tan2 and Cynthia Y. He1
Trypanosoma brucei is a blood-borne, protozoan parasite that causes African sleeping sickness in humans and nagana in animals. The current chemotherapy relies on only a handful of drugs that display undesirable toxicity, poor efficacy and drug-resistance. In this study, we explored the use of lysosomotropic drugs to induce bloodstream form T. brucei cell death via lysosome destabilization. We measured drug concentrations that inhibit cell proliferation by 50% (IC50) for several compounds, chosen based on their lysosomotropic effects previously reported in Plasmodium falciparum. The lysosomal effects and cell death induced by L-leucyl-L-leucyl methyl ester (LeuLeu-OMe) were further analyzed by flow cytometry and immunofluorescence analyses of different lysosomal markers...
In Entamoeba histolytica, a BspA family protein is required for chemotaxis toward tumour necrosis factor
Anne Silvestre1, 2, 3, 4, Aurélie Plaze1, 2, Patricia Berthon3, 4, Roman Thibeaux1, 2, Nancy Guillen1, 2 and Elisabeth Labruyère1, 2
Background: Entamoeba histolytica cell migration is essential for the development of human amoebiasis (an infectious disease characterized by tissue invasion and destruction). The tissue inflammation associated with tumour necrosis factor (TNF) secretion by host cells is a well-documented feature of amoebiasis. Tumour necrosis factor is a chemoattractant for E. histolytica, and the parasite may have a TNF receptor at its cell surface. Methods: confocal microscopy, RNA Sequencing, bioinformatics, RNA antisense techniques and histological analysis of human colon explants were used to characterize the interplay between TNF and E. histolytica. Results: an antibody against human TNF receptor 1 (TNFR1) stained the E. histolytica trophozoite...
Human Thyroid Cancer-1 (TC-1) is a vertebrate specific oncogenic protein that protects against copper and pro-apoptotic genes in yeast
Natalie K. Jones1,2,4,#, Nagla T.T. Arab1,3,#, Rawan Eid1,3,#, Nada Gharib1,5, Sara Sheibani1,2,6, Hojatollah Vali2, Chamel Khoury1, Alistair Murray1,2, Eric Boucher2, Craig A. Mandato2, Paul G. Young3 and Michael T. Greenwood1
The human Thyroid Cancer-1 (hTC-1) protein, also known as C8orf4 was initially identified as a gene that was up-regulated in human thyroid cancer. This article reports that hTC-1 is a peptide that prevents the effects of over-expressing Bax in yeast. In sum, the results indicate that hTC-1 is a pro-survival protein that retains its function when heterologously expressed in yeast. Thus yeast is a useful model to characterize the potential roles in cell death and survival of cancer related genes.
Polyamines directly promote antizyme-mediated degradation of ornithine decarboxylase by the proteasome
R. Roshini Beenukumar1,#, Daniela Gödderz1,2,#, R. Palanimurugan1,3, and R. Jürgen Dohmen1
Ornithine decarboxylase (ODC), a ubiquitin-independent substrate of the proteasome, is a homodimeric protein with a rate-limiting function in polyamine biosynthesis. Polyamines regulate ODC levels by a feedback mechanism mediated by ODC antizyme (OAZ). Higher cellular polyamine levels trigger the synthesis of OAZ and also inhibit its ubiquitin-dependent proteasomal degradation. OAZ binds ODC monomers and targets them to the proteasome. Here, we report that polyamines, aside from their role in the control of OAZ synthesis and stability, directly enhance OAZ-mediated ODC degradation by the proteasome. Using a stable mutant of OAZ, we show that polyamines promote ODC degradation in Saccharomyces cerevisiae cells even when OAZ levels are not changed. Furthermore, polyamines stimulated the in vitro degradation of ODC by the...
Toxoplasma gondii inhibits cytochrome c-induced caspase activation in its host cell by interference with holo-apoptosome assembly
Kristin Graumann1,3,#, Frieder Schaumburg1,4,#, Thomas F. Reubold2, Diana Hippe1, Susanne Eschenburg2 and Carsten G. K. Lüder1
Inhibition of programmed cell death pathways of mammalian cells often facilitates the sustained survival of intracellular microorganisms. The apicomplexan parasite Toxoplasma gondii is a master regulator of host cell apoptotic pathways. Here, we have characterized a novel anti-apoptotic activity of T. gondii. Using a cell-free cytosolic extract model, we show that T. gondii interferes with the activities of caspase 9 and caspase 3/7 which have been induced by exogenous cytochrome c and dATP. Proteolytic cleavage of caspases 9 and 3 is also diminished suggesting inhibition of holo-apoptosome function. Parasite infection of Jurkat T cells and subsequent triggering of apoptosome formation by exogenous cytochrome c in vitro and in vivo indicated that...
Exogenous folates stimulate growth and budding of Candida glabrata
Afsaneh Porzoor and Ian G. Macreadie
Folate, vitamin B9, is well recognized as being essential for cell growth. The utilization of folate is common to all cells, but the source of it may be quite different. This article reports a novel response of yeast to folates that may increase the utility of yeast as a model to study folate transport and signaling.
Modeling human Coenzyme A synthase mutation in yeast reveals altered mitochondrial function, lipid content and iron metabolism
Camilla Ceccatelli Berti1, Cristina Dallabona1, Mirca Lazzaretti1, Sabrina Dusi2, Elena Tosi1, Valeria Tiranti2, Paola Goffrini1
Mutations in nuclear genes associated with defective coenzyme A biosynthesis have been identified as responsible for some forms of neurodegeneration with brain iron accumulation (NBIA), namely PKAN and CoPAN. Yeast expressing a pathogenic mutation exhibited a temperature-sensitive growth defect in the absence of pantothenate and a reduced CoA content. Additional characterization revealed decreased oxygen consumption, reduced activities of mitochondrial respiratory complexes, higher iron content, increased sensitivity to oxidative stress and reduced amount of lipid droplets, thus partially recapitulating the phenotypes found in patients and establishing yeast as a potential model to clarify the pathogenesis underlying PKAN and CoPAN diseases.
Prokaryotic ancestry and gene fusion of a dual localized peroxiredoxin in malaria parasites
Carine F. Djuika1, Jaime Huerta-Cepas2, Jude M. Przyborski3, Sophia Deil1, Cecilia P. Sanchez1, Tobias Doerks2, Peer Bork2, Michael Lanzer1 and Marcel Deponte1
Horizontal gene transfer has emerged as a crucial driving force for the evolution of eukaryotes. This also includes Plasmodium falciparum and related economically and clinically relevant apicomplexan parasites, whose rather small genomes have been shaped not only by natural selection in different host populations but also by horizontal gene transfer following endosymbiosis. However, there is rather little reliable data on horizontal gene transfer between animal hosts or bacteria and apicomplexan parasites. Here we show that apicomplexan homologues of peroxiredoxin 5 (Prx5) have a prokaryotic ancestry and therefore represent a special subclass of Prx5 isoforms in eukaryotes. Using two different immunobiochemical approaches, we found that...
Non-canonical regulation of glutathione and trehalose biosynthesis characterizes non-Saccharomyces wine yeasts with poor performance in active dry yeast production
January 26, 2018
Several yeast species, belonging to Saccharomyces and non-Saccharomyces genera, play fundamental roles during spontaneous must grape fermentation, and recent studies have shown that mixed fermentations, co-inoculated with S. cerevisiae and non-Saccharomyces strains, can improve wine organoleptic properties. Here, Gamero-Sandemetrio et al. present findings that non-canonical regulation of glutathione and trehalose biosynthesis could cause poor fermentative performance after active dry yeast (ADY) production, as it corroborates the corrective effect of antioxidant treatments, during biomass propagation, with both pure chemicals and food-grade argan oil.
Molecular signature of the imprintosome complex at the mating-type locus in fission yeast
January 16, 2018
Genetic and molecular studies have indicated that an epigenetic imprint at mat1, the sexual locus of fission yeast, initiates mating type switching. Here, Raimondi et al. characterized the recruitment of early players of mating type switching at the mat1 region and suggest a nucleoprotein protective structure defined as imprintosome.
A novel system to monitor mitochondrial translation in yeast
January 13, 2018
In this study Suhm et al. present a novel system to monitor mitochondrial translation by detection of mitochondrial GFP-translation through fluorescence microscopy and flow cytometry in functional mitochondria. This novel tool allows the investigation of the function and regulation of mitochondrial translation during stress signaling, aging and mitochondrial biogenesis.
Fat storage-inducing transmembrane (FIT or FITM) proteins are related to lipid phosphatase/phosphotransferase enzymes
December 28, 2017
Fat storage-inducing transmembrane (FIT or FITM) proteins have been implicated in the partitioning of triacylglycerol to lipid droplets and the budding of lipid droplets from the ER. Saccharomyces cerevisiae has two FITM homologues and the presented results suggest that Scs3p and Yft2p as well as FITMs in general are lipid phosphatase/phosphotransferase (LPT) enzymes involved in an as yet unknown critical step in phospholipid metabolism.
Yeast quiescence exit swiftness is influenced by cell volume and chronological age
December 6, 2017
Quiescence exit swiftness is crucial not only for micro-organisms in competition for an environmental niche, such as yeast, but also for the maintenance of tissue homeostasis in multicellular species. Here, Laporte et al. explore the effect of replicative and chronological age on Saccharomyces cerevisiae quiescence exit efficiency. Overall, their data illustrate that the quiescent state is a continuum evolving with time, early and deep quiescence being distinguishable by the cell’s proficiency to re-enter the proliferation cycle.
A versatile plasmid system for reconstitution and analysis of mammalian ubiquitination cascades in yeast
December 5, 2017
In this article Avagliano Trezza et al. describe a versatile vector system that allows the reconstitution of specific ubiquitination cascades in the model eukaryote Saccharomyces cerevisae (baker’s yeast) that provides a versatile tool to study complex post-translational modifications in a cellular setting.
Alcohols enhance the rate of acetic acid diffusion in S. cerevisiae : biophysical mechanisms and implications for acetic acid tolerance
December 1, 2017
Microbial cell factories with the ability to maintain high productivity in the presence of weak organic acids, such as acetic acid, are required in many industrial processes. This study demonstrates that the rate of acetic acid diffusion can be strongly affected by compounds that partition into the cell membrane, and highlights the need for considering interaction effects between compounds in the design of microbial processes.
A genome-wide screen for FTY720-sensitive mutants reveals genes required for ROS homeostasis
November 27, 2017
Fingolimod hydrochloride (FTY720) is an immune modulator for multiple sclerosis that also induces cancer cell apoptosis through reactive oxygen species generation, with a new study using fission yeast uncovering a gene network related to ROS homeostasis as a possible mechanism of FTY720's toxicity.