Research Articles
Clostridium scindens promotes gallstone formation by inducing intrahepatic neutrophil extracellular traps through CXCL1 produced by colonic epithelial cells
Wenchao Yao1,a, Yuanhang He2,3,a, Zhihong Xie2,3, Qiang Wang2,3, Yang Chen2,4, Jingjing Yu2,3, Xuxu Liu2,3, Dongbo Xue2,3 , Liyi Wang2,3 and Chenjun Hao2,3
Through in vivo and in vitro experiments, we validated the reliability of C. scindens stimulating colonic epithelial cells to produce TLR2, activating the NF-κB signaling pathway, promoting CXCL1 expres-sion, and inducing intrahepatic neutrophil NETosis, which may be associated with gallstone formation.
Integrative Omics reveals changes in the cellular landscape of peroxisome-deficient pex3 yeast cells
Tjasa Kosir1,a, Hirak Das2,a, Marc Pilegaard Pedersen1, Ann-Kathrin Richard2, Marco Anteghini3,4, Vitor Martins dos Santos4,5, Silke Oeljeklaus2, Ida J. van der Klei1 and Bettina Warscheid2
To uncover the consequences of peroxisome deficiency, we compared Saccharomyces cerevisiae wild-type with pex3 cells, which lack peroxisomes, employing quantitative proteomics and transcriptomics technologies.
A complex remodeling of cellular homeostasis distinguishes RSV/SARS-CoV-2 co-infected A549-hACE2 expressing cell lines
Claudia Vanetti1, Irma Saulle1,2, Valentina Artusa1,2, Claudia Moscheni1, Gioia Cappelletti1, Silvia Zecchini1, Sergio Strizzi1, Micaela Garziano1,2, Claudio Fenizia1,2, Antonella Tosoni1, Martina Broggiato1, Pasquale Ogno1, Manuela Nebuloni1, Mario Clerici2,3, Daria Trabattoni1, Fiona Limanaqi1 and Mara Biasin1
Given the common tropism of SARS-CoV-2 and RSV, and the unclear consequences of their mutual influence, we developed an in vitro lung epithelial cell model to study the molecular mechanisms and cellular pathways modulated in viral co-infection.
RidA proteins contribute to fitness of S. enterica and E. coli by reducing 2AA stress and moderating flux to isoleucine biosynthesis
Ronnie L. Fulton, Bryce R. Sawyer and Diana M Downs
This study solidifies the established role of RidA in removing 2AA, while also presenting evidence for a role of RidA in enhancing flux towards isoleucine biosynthesis in E. coli. Overall, these data emphasize that metabolic networks can generate distinct responses to perturbation, even when the individual components are conserved.
Fecal gelatinase does not predict mortality in patients with alcohol-associated hepatitis
Yongqiang Yang1,a, Philipp Hartmann2,3,a and Bernd Schnabl1,4
This study aimed to investigate the significance of fecal gelatinase on clinical outcomes in patients with alcohol-associated hepatitis. In conclusion, in our cohort, fecal gelatinase does not predict mortality and does not indicate higher disease severity in patients with alcohol-associated hepatitis.
Promoter methylation and increased expression of PD-L1 in patients with active tuberculosis
Yen-Han Tseng1,2, Sheng-Wei Pan1,2,3, Jhong-Ru Huang2,4, Chang-Ching Lee1, Jung-Jyh Hung2,5, Po-Kuei Hsu2,5, Nien-Jung Chen6, Wei-Juin Su2,7, Yuh-Min Chen1,2 and Jia-Yih Feng1,2,8
The PD-1/PD-L1 pathway plays a pivotal role in T cell activity and is involved in the pathophysiology of tuberculosis. Here we show that PD-L1 expression is increased in patients with active tuberculosis and is correlated with treatment outcomes.
Quantification methods of Candida albicans are independent irrespective of fungal morphology
Amanda B Soares1, Maria C de Albuquerque1, Leticia M Rosa1, Marlise I Klein 2, Ana C Paravina1, Paula A Barbugli1, Livia N Dovigo3 and Ewerton G de O Mima1
Our study demonstrated that the quantification methods of C. albicans (cells/mL, CFU/mL, and vPCR) did not agree, regardless of the fungal morphology/growth, even though a significant and strong correlation is observed.
Pathogenic Escherichia coli change the adhesion between neutrophils and endotheliocytes in the experimental bacteremia model
Svetlana N Pleskova1,2,*, Nikolay A Bezrukov1, Sergey Z Bobyk1, Ekaterina N Gorshkova1 and Dimitri V Novikov3
In this work, we have demonstrated that in the model of experimental septicemia there is a disruption of adhesion contacts between neutrophils and endothelial cells, manifested by a decrease in adhesion force and work upon exposure to E. coli.
Arsenite treatment induces Hsp90 aggregates distinct from conventional stress granules in fission yeast
Naofumi Tomimotoa, Teruaki Takasakia and Reiko Sugiura
Given the conserved role of Hsp90 as a molecular chaperone protein, our findings presented in this study may suggest a novel type of arsenite-induced biological condensates, wherein Hsp90 plays a key role in maintaining its integrity.
Oxygen availability strongly affects chronological lifespan and thermotolerance in batch cultures of Saccharomyces cerevisiae
October 22, 2015
Stationary-phase (SP) batch cultures of Saccharomyces cerevisiae, in which growth has been arrested by carbon-source depletion, are widely applied to study chronological lifespan, quiescence and SP-associated robustness. Based on this type of experiments, typically performed under aerobic conditions, several roles of oxygen in aging have been proposed. However, SP in anaerobic yeast cultures has not been investigated in detail. Here, we use the unique capability of S. cerevisiae to grow in the complete absence of oxygen to directly compare SP in aerobic and anaerobic bioreactor cultures. This comparison revealed strong positive effects of oxygen availability on adenylate energy charge, longevity and thermotolerance during SP. A low thermotolerance of...
DNA damage checkpoint adaptation genes are required for division of cells harbouring eroded telomeres
September 21, 2015
In budding yeast, telomerase and the Cdc13p protein are two key players acting to ensure telomere stability. This article shows that while the capping process can be flexible, it takes a very specific genetic setup to allow a change from canonical capping to alternative capping.
The MAPKKKs Ste11 and Bck1 jointly transduce the high oxidative stress signal through the cell wall integrity MAP kinase pathway
September 6, 2015
Oxidative stress stimulates the Rho1 GTPase, which in turn induces the cell wall integrity (CWI) MAP kinase cascade. CWI activation promotes stress-responsive gene expression through activation of transcription factors (Rlm1, SBF) and nuclear release and subsequent destruction of the repressor cyclin C. This study reports that, in response to high hydrogen peroxide exposure, or in the presence of constitutively active Rho1, cyclin C still translocates to the cytoplasm and is degraded in cells lacking Bck1, the MAPKKK of the CWI pathway.
Formyl-methionine as a degradation signal at the N-termini of bacterial proteins
September 6, 2015
Varshavsky and colleagues solve a long-standing mystery in proteolysis! In bacteria, all nascent proteins bear the pretranslationally formed N-terminal formyl-methionine (fMet) residue. The fMet residue is cotranslationally deformylated by a ribosome-associated deformylase. The formylation of N-terminal Met in bacterial proteins is not strictly essential for either translation or cell viability. Moreover, protein synthesis by the cytosolic ribosomes of eukaryotes does not involve the formylation of N-terminal Met. What, then, is the main biological function of this metabolically costly, transient, and not strictly essential modification of N‑terminal Met, and why has Met formylation not been eliminated during bacterial evolution? One possibility is that the similarity of the formyl and acetyl groups, their identical locations in...
A single mutation in the 15S rRNA gene confers non sense suppressor activity and interacts with mRF1 the release factor in yeast mitochondria
August 2, 2015
This article presents the nucleotide sequence of the mim3-1 mitochondrial ribosomal suppressor, acting on ochre mitochondrial mutations and one frameshift mutation in Saccharomyces cerevisiae. A hypothetical mechanism of suppression by "ribosome shifting" is also discussed in view of the nature of mutations suppressed and not suppressed.
The lysosomotropic drug LeuLeu-OMe induces lysosome disruption and autophagy-independent cell death in Trypanosoma brucei
July 30, 2015
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
July 6, 2015
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
June 25, 2015
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
May 20, 2015
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
May 4, 2015
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...