An atypical active cell death process underlies the fungicidal activity of ciclopirox olamine against the yeast Saccharomyces cerevisiae

Financial Inclusion Paradigm Shift in the Postpandemic Period. Digital-Divide and Gender Gap

Financial inclusion is strongly differentiated by age groups and countries and the pandemic has highlighted the increased gaps and inequalities but also the weaknesses of the system, in terms of flexibility, access and facilities of the customer-bank relationship and also from the perspective of the financial education of young generations and vulnerable people, active in the labor market. Based on the available data provided by the Global Findex database, and some findings after more than one year of COVID-19 crisis we outlined the main aspects of financial digitization, by categories of people and countries. At the same time, we identified the challenges and problems during the pandemic that significantly adjusted the consumption pattern of citizens and increased the need for on-line access for financial transactions. Starting from the analysis of the inequality of access to financial instruments in the last years, from the informational asymmetry in financial education and the challenges of the pandemic period, we underlined the main coordinates of changing the model of sustainable financial inclusion-based on five pillars-access, education, support tools, CSR and resilience. The research results highlight the need for convergence in providing opportunities to consider financial inclusion as a public good and an active tool to increase consumers' satisfaction and the quality of life of individuals.

Mitophagy Improves Ethanol Tolerance in Yeast: Regulation by Mitochondrial Reactive Oxygen Species in Saccharomyces cerevisiae

Ethanol often accumulates during the process of wine fermentation, and mitophagy has critical role in ethanol output. However, the relationship between mitophagy and ethanol stress is still unclear. In this study, the expression of ATG11 and ATG32 genes exposed to ethanol stress was accessed by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The result indicated that ethanol stress induced expression of the ATG11 and ATG32 genes. The colony sizes and the alcohol yield of atg11 and atg32 were also smaller and lower than those of wild type strain under ethanol whereas the mortality of mutants is higher. Furthermore, compared with wild type, the membrane integrity and the mitochondrial membrane potential of atg11 and atg32 exhibited greater damage following ethanol stress. In addition, a greater proportion of mutant cells were arrested at the G1/G0 cell cycle. There was more aggregation of peroxide hydrogen (H₂O₂) and superoxide anion (O₂^•-) in mutants. These changes in H₂O₂ and O₂^•- in yeasts were altered by reductants or inhibitors of scavenging enzyme by means of regulating the expression of ATG11 and ATG32 genes. Inhibitors of the mitochondrial electron transport chain (mtETC) also increased production of H₂O₂ and O₂^•- by enhancing expression of the ATG11 and ATG32 genes. Further results showed that activator or inhibitor of autophagy also activated or inhibited mitophagy by altering production of H₂O₂ and O₂^•. Therefore, ethanol stress induces mitophagy which improves yeast the tolerance to ethanol and the level of mitophagy during ethanol stress is regulated by ROS derived from mtETC.

Cellular apoptosis: An alternative mechanism of action for caspofungin against Candida glabrata

Background and Purpose:

Although the mechanism of action for echinocandins is known, the physiological mechanisms by which these antifungal agents cause cell death via the classical apoptotic pathways are not well-defined yet. Regarding this, the present study aimed to evaluate the mechanisms of caspofungin-induced Candida glabrata cell death.

Materials and Methods:

For the purpose of the study, the minimum inhibitory concentration (MIC) of caspofungin against C. glabrata (ATCC 90030) was determined using the broth microdilution reference method (CLSI M27-A2 and M27-S4). The annexin V and propidium iodide staining was performed to determine the way through which caspofungin acts against C. glabrata (i.e., through the induction of apoptosis and/or necrosis). Additionally, the possible effect of caspofungin on inducing the expression of two apoptotic genes, namely MCA1 and NUC, was studied using the real-time polymerase chain reaction assay.

Results:

According to the obtained MIC value (0.5 µg/mL), C. glabrata, exposed to 0.25, 0.5, and 1 µg/mL of caspofungin, exhibited the features of late apoptosis/necrosis after 18 h of incubation. Furthermore, the use of 0.25, 0.5, and 1 µg/ml caspofungin induced apoptosis (early/late) in 14.67%, 17.04%, and 15.89% of the cells, respectively. The results showed a significant difference between the percentages of early-apoptotic cells at the three concentrations (P<0.05). In addition, the rate of necrosis was significantly greater than that of apoptosis in response to caspofungin. Accordingly, necrosis occurred in 71.26%, 71.26%, and 61.26% of the cells at the caspofungin concentrations of 0.25, 0.5, and 1 µg/mL, respectively (P<0.05). The analysis of the data in the REST software demonstrated a significant increase in the expression of MCA1 and NUC1 genes (P<0.05).

Conclusion:

As the findings of the present study indicated, caspofungin promoted both necrosis and apoptosis of C. glabrata cells at concentrations higher than or equal to the MIC value.

Guidelines and recommendations on yeast cell death nomenclature

Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cel-lular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the defi-nition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differ-ential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death rou-tines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the au-thors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the pro-gress of this vibrant field of research.

Glabridin triggers over-expression of MCA1 and NUC1 genes in Candida glabrata: Is it an apoptosis inducer?

The growing trends of emergence of antifungal-resistant Candida strains has recently been inspired the researchers to design new antifungal agents with novel mechanisms of action. Glabridin is an originally natural substrate with multiple biological activities which propose it as a novel anticancer, antimicrobial and antifungal agent. In the present study, the antifungal effect of glabridin against Candida glabrata isolates and its possible mechanism of action were investigated. The minimum inhibitory concentrations (MIC) for glabridin against fluconazole-resistant and fluconazole-SDD strains of C. glabrata were investigated using the Clinical and laboratory standards institute document M27-A3 and M27-S4 as a guideline. Possible alternations in the expression of two critical genes involved in yeast apoptosis, MCA1 and NUC1, were assayed by real-time PCR. DNA damage and chromatin condensation was investigated using DAPI staining. Although glabridin led to a significant decrease in MICs against fluconazole-resistant C. glabrata (MIC₅₀: 8μg/mL), no significant decreased was shown for fluconazole-SDD strains. Therefore, a distinct azole-independent mechanism could be responsible for the inhibitory activity of glabridin. Overexpression of MCA1 and NUC1 genes in addition to DNA damage and chromatin condensation suggesting the involvement of apoptosis signaling in C. glabrata stains exposed to glabridin. This study suggests that glabridin might be considered as a novel naturally originated agent to fight against fluconazole-resistance C. glabrata strains.

Drug-Based Lead Discovery: The Novel Ablative Antiretroviral Profile of Deferiprone in HIV-1-Infected Cells and in HIV-Infected Treatment-Naive Subjects of a Double-Blind, Placebo-Controlled, Randomized Exploratory Trial

Antiretrovirals suppress HIV-1 production yet spare the sites of HIV-1 production, the HIV-1 DNA-harboring cells that evade immune detection and enable viral resistance on-drug and viral rebound off-drug. Therapeutic ablation of pathogenic cells markedly improves the outcome of many diseases. We extend this strategy to HIV-1 infection. Using drug-based lead discovery, we report the concentration threshold-dependent antiretroviral action of the medicinal chelator deferiprone and validate preclinical findings by a proof-of-concept double-blind trial. In isolate-infected primary cultures, supra-threshold concentrations during deferiprone monotherapy caused decline of HIV-1 RNA and HIV-1 DNA; did not allow viral breakthrough for up to 35 days on-drug, indicating resiliency against viral resistance; and prevented, for at least 87 days off-drug, viral rebound. Displaying a steep dose-effect curve, deferiprone produced infection-independent deficiency of hydroxylated hypusyl-eIF5A. However, unhydroxylated deoxyhypusyl-eIF5A accumulated particularly in HIV-infected cells; they preferentially underwent apoptotic DNA fragmentation. Since the threshold, ascertained at about 150 μM, is achievable in deferiprone-treated patients, we proceeded from cell culture directly to an exploratory trial. HIV-1 RNA was measured after 7 days on-drug and after 28 and 56 days off-drug. Subjects who attained supra-threshold concentrations in serum and completed the protocol of 17 oral doses, experienced a zidovudine-like decline of HIV-1 RNA on-drug that was maintained off-drug without statistically significant rebound for 8 weeks, over 670 times the drug's half-life and thus clearance from circulation. The uniform deferiprone threshold is in agreement with mapping of, and crystallographic 3D-data on, the active site of deoxyhypusyl hydroxylase (DOHH), the eIF5A-hydroxylating enzyme. We propose that deficiency of hypusine-containing eIF5A impedes the translation of mRNAs encoding proline cluster ('polyproline')-containing proteins, exemplified by Gag/p24, and facilitated by the excess of deoxyhypusine-containing eIF5A, releases the innate apoptotic defense of HIV-infected cells from viral blockade, thus depleting the cellular reservoir of HIV-1 DNA that drives breakthrough and rebound.

TRIAL REGISTRATION

ClinicalTrial.gov NCT02191657.

New Insights Regarding Yeast Survival following Exposure to Liposomal Amphotericin B

In vitro resistance to amphotericin B is an extremely rare event among pathogenic yeasts. However, in vivo response is sometimes reduced, resulting in an unfavorable outcome. Such adverse outcomes might be related to subfungicidal plasma concentrations. We aimed to clarify the mechanisms of liposomal amphotericin B (AMB-L; AmBisome)-induced lesions and the mechanisms responsible for yeast cell recovery following exposure at plasma concentrations. The physiological statuses developing following exposure to AMB-L at simulated plasma concentrations (20 to 0.1 mg/liter) and at a constant concentration (3 mg/liter) were assessed in a 24-h time course assay. Time-kill experiments also were carried out under the same AMB-L treatment conditions. Our results suggest that yeast cells develop compensatory responses related to membrane polarization, metabolic activity, and reactive oxygen species (ROS) production after exposure to high plasma concentrations (20 to 5 mg/liter) during the first 6 h; in the remaining 18 h, when exposed to lower concentrations, cells reveal almost full recovery with no evidence of fungicidal activity. In contrast, whenever cells are exposed to a constant concentration above the MIC, despite initially exhibiting compensatory stress responses, soon afterwards they exhibit membrane depolarization, a decrease of metabolic activity, increasing ROS production, and lastly, programmed cell death and necrosis, resulting in succumbing to AMB-L fungicidal effects. This study may represent a step forward in the support of AMB-L use for clinical treatment of invasive fungal infections, since it demonstrates the importance of maintaining levels of AMB-L above the MIC in plasma and tissues to ensure it produces its fungicidal effects.

Response of Saccharomyces cerevisiae to the stimulation of lipopolysaccharide

Lipopolysaccharide, known as endotoxin, can stimulate potent host immune responses through the complex of Toll-like-receptor 4 and myeloid differentiation protein 2; but its influence on Saccharomyces cerevisiae, a model organism for studying eukaryotes, is not clear. In this study, we found that lipopolysaccharide-treated S. cerevisiae cells could be stained by methylene blue, but did not die. Transcriptional profiling of the lipopolysaccharide-treated S. cerevisiae cells showed that 5745 genes were modulated: 2491 genes up-regulated and 3254 genes down-regulated. Significantly regulated genes (460 up-regulated genes and 135 down-regulated genes) in lipopolysaccharide-treated S. cerevisiae cells were analyzed on Gene Ontology, and used to establish physical protein-protein interaction network and protein phosphorylation network. Based on these analyses, most of the regulated genes in lipopolysaccharide-treated S. cerevisiae cells were related to cell wall, membrane, peroxisome and mitochondrion. Further experiments demonstrated that lipopolysaccharide stimulation caused the exposure of phosphatidylserine and the increase of mitochondrial membrane potential in S. cerevisiae cells, but levels of intracellular reactive oxygen species and metacaspase activation were not increased. This study demonstrated that lipopolysaccharide stimulation causes significant changes in S. cerevisiae cells, and the results would contribute to understand the response of eukaryotic cells to lipopolysaccharide stimulation.

Exploitation of genomics in fungicide research: current status and future perspectives

Every year, fungicide use to control plant disease caused by pathogenic fungi increases. The global fungicide market is now worth more than £5.3 billion, second only to the herbicide market in importance. In the UK, over 5500 tonnes of fungicide were applied to crops in 2010 (The Food and Environment Research Agency, Pesticide Usage Statistics), with 95.5% of the wheat-growing area receiving three fungicide sprays. Although dependence on fungicides to produce food securely, reliably and cheaply may be moderated in the future by further developments in crop biotechnology, modern crop protection will continue to require a diversity of solutions, including effective and safe chemical control. Therefore, investment in exploiting the increasingly available genome sequences of the most devastating fungal and oomycete phytopathogenic species should bring an array of new opportunities for chemical intervention. To date, the impact of whole genome research on the development, introduction and stewardship of fungicides has been limited, but ongoing improvements in computational analysis, molecular biology, chemical genetics, genome sequencing and transcriptomics will facilitate the development and registration of the future suite of crop protection chemicals.

Caspofungin kills Candida albicans by causing both cellular apoptosis and necrosis

Caspofungin exerts candidacidal activity by inhibiting cell wall (1,3)-β-d-glucan synthesis. We investigated the physiologic mechanisms of caspofungin-induced Candida albicans cell death. Apoptosis (programmed cell death) and necrosis were studied after C. albicans SC5314 cells were exposed to caspofungin at 0.06, 0.125, and 0.5 μg/ml (0.5×, 1×, and 4× the MIC, respectively) for 3 h. Caspofungin at 0.125 and 0.5 μg/ml reduced cellular viability by >50%, as measured by colony counts and methylene blue exclusion. Apoptosis and necrosis were demonstrated by annexin V and propidium iodide staining for phosphatidylserine externalization and loss of membrane integrity, respectively. At all concentrations of caspofungin, 20 to 25% and 5 to 7% of C. albicans cells exhibited early apoptosis and late apoptosis/necrosis, respectively (P value was not significant [NS]). Necrosis, on the other hand, was significantly greater at 0.125 (43%) and 0.5 (48%) μg/ml than at 0.06 μg/ml (26%) (P values of 0.003 and 0.003, respectively). The induction of apoptosis at concentrations less than or equal to the MIC was corroborated by dihydrorhodamine 123 (DHR-123) and dihydroethidium (DHE) staining (reactive oxygen species production), JC-1 staining (mitochondrial membrane potential dissipation), and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) staining (DNA damage and nuclear fragmentation). Moreover, electron microscopy of cells exposed to 0.125 μg/ml of caspofungin showed hallmark apoptotic features like chromatin margination and condensation and nuclear blebs. Apoptosis was associated with metacaspase 1 activation, as demonstrated by D2R staining. Caspofungin exerts activity against C. albicans by directly killing cells (resulting in necrosis) and causing others to undergo programmed cell death (apoptosis). Apoptosis is initiated at subinhibitory concentrations, suggesting that strategies to target this process may augment the benefits of antifungal agents.

The antitumor activity of the fungicide ciclopirox

Ciclopirox olamine (CPX) is a synthetic antifungal agent clinically used to treat mycoses of the skin and nails. Here, we show that CPX inhibited tumor growth in human breast cancer MDA-MB-231 xenografts. To unveil the underlying mechanism, we further studied the antitumor activity of CPX in cell culture. The results indicate that CPX inhibited cell proliferation and induced apoptosis in human rhabdomyosarcoma (Rh30), breast carcinoma (MDA-MB231) and colon adenocarcinoma (HT-29) cells in a concentration-dependent manner. By cell cycle analysis, CPX induced accumulation of cells in G(1)/G(0) phase of the cell cycle. Concurrently, CPX downregulated cellular protein expression of cyclins (A, B1, D1 and E) and cyclin-dependent kinases (CDK2 and CDK4) and upregulated expression of the CDK inhibitor p21(Cip1), leading to hypophosphorylation of retinoblastoma protein. CPX also downregulated protein expression of Bcl-xL and survivin and enhanced cleavages of Bcl-2. Z-VAD-FMK, a pan-caspase inhibitor, partially prevented CPX-induced cell death, suggesting that CPX-induced apoptosis of cancer cells is mediated at least in part through caspase-dependent mechanism. The results indicate that CPX is a potential antitumor agent.

Accumulation of non-superoxide anion reactive oxygen species mediates nitrogen-limited alcoholic fermentation by Saccharomyces cerevisiae

Throughout alcoholic fermentation, nitrogen depletion is one of the most important environmental stresses that can negatively affect the yeast metabolic activity and ultimately leads to fermentation arrest. Thus, the identification of the underlying effects and biomarkers of nitrogen limitation is valuable for controlling, and therefore optimizing, alcoholic fermentation. In this study, reactive oxygen species (ROS), plasma membrane integrity, and cell cycle were evaluated in a wine strain of Saccharomyces cerevisiae during alcoholic fermentation in nitrogen-limiting medium under anaerobic conditions. The results indicated that nitrogen limitation leads to an increase in ROS and that the superoxide anion is a minor component of the ROS, but there is increased activity of both Sod2p and Cta1p. Associated with these effects was a decrease in plasma membrane integrity and a persistent cell cycle arrest at G(0)/G(1) phases. Moreover, under these conditions it appears that autophagy, evaluated by ATG8 expression, is induced, suggesting that this mechanism is essential for cell survival but does not prevent the cell cycle arrest observed in slow fermentation. Conversely, nitrogen refeeding allowed cells to reenter cell cycle by decreasing ROS generation and autophagy. Altogether, the results provide new insights on the understanding of wine fermentations under nitrogen-limiting conditions and further indicate that ROS accumulation, evaluated by the MitoTracker Red dye CM-H(2)XRos, and plasma membrane integrity could be useful as predictive markers of fermentation problems.

Formic acid induces Yca1p-independent apoptosis-like cell death in the yeast Saccharomyces cerevisiae

Formic acid disrupts mitochondrial electron transport and sequentially causes cell death in mammalian ocular cells by an unidentified molecular mechanism. Here, we show that a low concentration of formic acid induces apoptosis-like cell death in the budding yeast Saccharomyces cerevisiae, with several morphological and biochemical changes that are typical of apoptosis, including chromatin condensation, DNA fragmentation, externalization of phosphatidylserine, reactive oxygen species (ROS) production, loss of mitochondrial membrane potential and mitochondrion destruction. This process may not be dependent on the activation of Yca1p, the yeast caspase counterpart. In addition, the cell death induced by formic acid is associated with ROS burst,while intracellular ROS accumulate more rapidly and to a higher level in the YCA1 disruptant than in the wild-type strain during the progression of cell death. Our data indicate that formic acid induces yeast apoptosis via an Yca1p-independent pathway and it could be used as an extrinsic inducer for identifying the regulators downstream of ROS production in yeast.

Drug-induced apoptosis in yeast

In order to alter the impact of diseases on human society, drug development has been one of the most invested research fields. Nowadays, cancer and infectious diseases are leading targets for the design of effective drugs, in which the primary mechanism of action relies on the modulation of programmed cell death (PCD). Due to the high degree of conservation of basic cellular processes between yeast and higher eukaryotes, and to the existence of an ancestral PCD machinery in yeast, yeasts are an attractive tool for the study of affected pathways that give insights into the mode of action of both antitumour and antifungal drugs. Therefore, we covered some of the leading reports on drug-induced apoptosis in yeast, revealing that in common with mammalian cells, antitumour drugs induce apoptosis through reactive oxygen species (ROS) generation and altered mitochondrial functions. The evidence presented suggests that yeasts may be a powerful model for the screening/development of PCD-directed drugs, overcoming the problem of cellular specificity in the design of antitumour drugs, but also enabling the design of efficient antifungal drugs, targeted to fungal-specific apoptotic regulators that do not have major consequences for human cells.

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. Microarray analysis showed that Isc1p deficiency up-regulated the iron regulon leading to increased levels of iron, which is known to catalyze the production of the highly reactive hydroxyl radicals via the Fenton reaction. In agreement, iron chelation suppressed hydrogen peroxide sensitivity of isc1Delta mutants. Cells lacking Isc1p also displayed a shortened chronological lifespan associated with oxidative stress markers and aging of parental cells was correlated with a decrease in Isc1p activity. The analysis of DNA fragmentation and caspase-like activity showed that Isc1p deficiency increased apoptotic cell death associated with oxidative stress and aging. Furthermore, deletion of Yca1p metacaspase suppressed the oxidative stress sensitivity and premature aging phenotypes of isc1Delta mutants. These results indicate that Isc1p plays an important role in the regulation of cellular redox homeostasis, through modulation of iron levels, and of apoptosis.

Nitric oxide signaling is disrupted in the yeast model for Batten disease

The juvenile form of neuronal ceroid lipofuscinoses (JNCLs), or Batten disease, results from mutations in the CLN3 gene, and it is characterized by the accumulation of lipopigments in the lysosomes of several cell types and by extensive neuronal death. We report that the yeast model for JNCL (btn1-Delta) that lacks BTN1, the homologue to human CLN3, has increased resistance to menadione-generated oxidative stress. Expression of human CLN3 complemented the btn1-Delta phenotype, and equivalent Btn1p/Cln3 mutations correlated with JNCL severity. We show that the previously reported decreased levels of L-arginine in btn1-Delta limit the synthesis of nitric oxide (.NO) in both physiological and oxidative stress conditions. This defect in .NO synthesis seems to suppress the signaling required for yeast menadione-induced apoptosis, thus explaining btn1-Delta phenotype of increased resistance. We propose that in JNCL, a limited capacity to synthesize .NO directly caused by the absence of Cln3 function may contribute to the pathology of the disease.