Biology subjects

Gil, C.

Publications and source records attributed to Gil, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Thirty years of fluconazole therapy selects an azole-resistant Candida albicans isolate with a pre-adapted physiological, metabolic and structural state

Azole resistance in Candida albicans is traditionally attributed to alterations in drug targets and efflux mechanisms; however, how long-term antifungal exposure reshapes fungal physiology remains incompletely understood. Here, we characterize a fluconazole-resistant C. albicans clinical isolate (PUJ256) recovered from a patient with chronic mucocutaneous candidiasis after more than 30 years of continuous fluconazole therapy. Compared with the reference strain SC5314, the resistant isolate exhibited a clear fitness trade-off, with reduced filamentation and increased membrane vulnerability under basal conditions, yet enhanced fitness in the presence of fluconazole. Integration of phenotypic analyses with label-free quantitative proteomics revealed extensive metabolic remodelling, including coordinated regulation of central carbon metabolism, ergosterol biosynthesis and redox homeostasis. Notably, mitochondrial membrane potential was preserved in the resistant isolate under fluconazole stress, whereas the susceptible strain exhibited mitochondrial depolarization together with activation of MAPK signalling pathways. In addition, the resistant isolate displayed reduced susceptibility to phagocytosis under antifungal exposure, consistent with an increased capacity for persistence in the context of ongoing treatment. Collectively, our findings indicate that long-term azole resistance in C. albicans PUJ256 is associated with a stable, pre-adapted physiological state characterized by metabolic reprogramming and mitochondrial resilience. The prolonged antifungal exposure of this isolate provides a valuable opportunity to explore adaptative strategies that extend beyond canonical mechanisms, pointing to mitochondrial function and metabolic plasticity as potential targets for therapeutic intervention.

microbiology↗

bioRxiv2026

Proteomics to uncover new actors in the antifungal action of metformin. Impact on virulence traits, oxidative stress, and essential proteins from Candida albicans.

Metformin is one of the most widely prescribed drugs with a proven safety profile, making it an excellent candidate for drug repurposing strategies. Its anti-Candida effect and its synergistic potential with azoles have already been described against C. albicans and C. glabrata, alongside AMPK involvement and its divergent consequences on autophagy. However, metformin has additional effects on C. albicans biology that remain to be explored using differential proteomics. In the present study, C. albicans SC5314 was treated with metformin to identify the proteins involved in its anti-Candida activity. First, we demonstrated that metformin inhibits C. albicans SC5314 growth in a dose-dependent manner, an effect that intensifies under low glucose (0.2%) and filament-inducing conditions. It also reduces virulence traits such as filamentation, biofilm formation, and invasive growth. Furthermore, it induces significant oxidative stress, which is neutralized by antioxidant agents such as N-acetylcysteine and glutathione. Additionally, 50 mM metformin substantially increased fluconazole efficacy under 0.2% glucose. Our label-free proteomic study of C. albicans SC5314 exposed to 50 mM metformin allowed the identification and quantification of 1,899 proteins, with 95 and 47 proteins showing increased and decreased abundance, respectively. Notably, 26 of the down-regulated proteins were encoded by essential genes, demonstrating the drastic effect of metformin on C. albicans viability. GO Term analysis revealed that the most relevant functions affected were ATP binding, inhibition of ATPase activity (with reduced ATP levels), translation inhibition, mitochondrial function, filamentation, and responses to oxidative stress and antifungals. In conclusion, metformin significantly compromises the viability and virulence of C. albicans at high concentrations. Given that high concentrations of metformin have recently been reported in the intestinal tract, and that intestinal Candida is a known source of invasive infections in immunocompromised, under chemotherapy, and post-surgery patients, understanding metformin anti-Candida action becomes increasingly relevant.

microbiology↗

bioRxiv2026

A generalizable normalization framework to decouple protocol and instrument effects: Application to high-sensitivity proteomics multicentric study (PME13)

Multicenter studies are essential for benchmarking analytical workflows, yet their interpretation is often confounded by the combined effects of experimental protocols and instrumentation. To address this challenge, we introduce a simple normalization-based analytical framework, the recovery metric ({rho}), designed to decouple protocol driven effects from instrument dependent variability. We applied this framework to the 13th Proteomics Multicentric Experiment (PME13), a large multicentric proteomics dataset generated across 27 laboratories using high sensitivity workflows and varying sample preparation protocols. By leveraging a common digested reference sample, {rho} enables direct cross-comparison of all datasets on a unified scale, effectively minimizing instrument-related biases. Using this approach, we demonstrate that apparent instrument dependent trends are largely removed when evaluated through {rho}, revealing consistent protocol driven effects across laboratories. Statistical modeling identified key variables influencing {rho}, including sample input amount, reduction and alkylation, and the use of n-dodecyl-{beta}-D-maltoside (DDM). While DDM was associated with improved {rho}, reduction and alkylation and additional handling steps led to reduced performance, particularly at low input levels. We further highlight practical considerations for the application of ratio based normalization, including the occurrence of values exceeding theoretical bounds, which reflect deviations from underlying assumptions and require appropriate filtering. Overall, this work establishes a generalizable analytical strategy for disentangling confounding factors in multicentric datasets and provides practical guidelines for optimizing high sensitivity proteomics (HSP) workflows. The proposed framework is broadly applicable to other analytical fields where cross laboratory comparability is required.

bioinformatics↗

bioRxiv2025

YAP/TAZ create a physical niche for the maintenance of adult neural stem cell quiescence

Adult stem cells inhabit specialized niches where local and systemic cues regulate their behavior. In the mouse ventricular-subventricular zone (V-SVZ), neural stem cells (NSCs) dynamically transition between quiescence and activation and reside amidst unique deposits of extracellular matrix (ECM) known as fractones. We show that NSCs that enter quiescence in response to BMP4 secrete a complex ECM that, on its own, is capable of inducing NSC quiescence. This specific ECM triggers the nuclear translocation of Yes-associated protein (YAP), to induce further ECM remodeling and adhesion. Together, the BMP-ECM-YAP pathway creates a two-step mechanism where a soluble and transient quiescence-inducing signal leads to the formation of a physical niche to maintain the quiescent state. In the intact niche, YAP and its paralog TAZ (Transcriptional coactivator with PDZ-binding motif) essentially sustain quiescence by preserving fractones and the characteristic structural organization. Moreover, our findings reveal a previously unrecognized role for YAP/TAZ in quiescence.

neuroscience↗

bioRxiv2025

iPSC-derived hepatocytes accurately recapitulate population diversity in alpha-1-antitrypsin deficiency and offer a novel in vitro model for large-scale drug efficacy screening studies.

BackgroundAlpha-1 antitrypsin deficiency (A1ATD) is a hereditary recessive disorder caused by mutations in the SERPINA1 gene. It is a clinically under-recognised disease characterised by low circulating A1AT levels and intracellular accumulation of misfolded A1AT in hepatocytes. Deposition of excessive abnormal A1AT in the liver leads to liver failure, yet no specific treatments are available due to the lack of physiologically relevant disease modelling platforms. MethodsWe have hypothesised that human induced pluripotent stem cell (iPSC)-derived hepatocytes can provide an efficient platform to study A1ATD. Using CRISPR/Cas9, we have generated wild-type and A1ATD iPSC-derived hepatocytes (Opti-HEP) from healthy and A1ATD donors and developed a bioassay that mimics the accumulation of misfolded A1AT in the liver. Responses to the reference drug carbamazepine (CBZ), known to reduce intracellular misfolded A1AT levels, and RNA-based therapeutics were subsequently investigated. ResultsAll lines successfully differentiated into hepatocytes as measured by comparable key hepatic and disease markers to those seen in primary human hepatocytes. The diseased lines displayed increased intracellular accumulation of misfolded A1AT compared to isogenic controls. Diseased cell lines showed significant decreases in intracellular accumulation of polymeric A1AT following transfection with RNA-based therapeutics, but a differential response upon treatment with CBZ. ConclusionWe have developed a specific and robust in vitro model of A1ATD that recapitulates disease pathophysiology and responds to small molecule-based treatments and advanced therapeutic strategies. These data demonstrate the suitability of this model for large-scale efficacy screening studies for the treatment of A1ATD and help pave the way towards the development of novel therapies.

cell biology↗

bioRxiv2024

Candida albicans a comprehensive view of the proteome

We describe a new release of the Candida albicans PeptideAtlas proteomics spectral resource (build 2024-03), providing a sequence coverage of 79.5% at the canonical protein level, matched mass spectrometry spectra, and experimental evidence identifying 3382 and 536 phosphorylated serine and threonine sites with false localization rates of 1% and 5.3%, respectively. We provide a tutorial on how to use the PeptideAtlas and associated tools to access this information. The C. albicans PeptideAtlas summary web page provides "Build overview", "PTM coverage", "Experiment contribution", and "Dataset contribution" information. The protein and peptide information can also be accessed via the Candida Genome Database via hyperlinks on each protein page. This allows users to peruse identified peptides, protein coverage, post-translational modifications (PTMs), and experiments identifying each protein. Given the value of understanding the PTM landscape in the sequence of each protein, a more detailed explanation of how to interpret and analyse PTM results is provided in the PeptideAtlas of this important pathogen. Candida albicans PeptideAtlas web page: https://db.systemsbiology.net/sbeams/cgi/PeptideAtlas/buildDetails?atlas_build_id=578

microbiology↗

bioRxiv2024

From high protection to lethal effect: diverse outcomes of immunization against invasive candidiasis with different Candida albicans extracellular vesicles

Extracellular vesicles (EVs) from Candida albicans can elicit immune responses, positioning them as promising acellular vaccine candidates. We characterized EVs from an avirulent C. albicans cell wall mutant (ecm33{Delta}) and evaluated their protective potential against invasive candidiasis. EVs from the yeast (YEVs) and hyphal (HEVs) forms of the SC5314 wild-type strain were also tested, yielding high survival rates with SC5314 YEVs (91%) and ecm33 YEVs immunization (64%). Surprisingly, HEV immunization showed a dual effect, resulting in 36% protection but also causing premature death in some mice. Proteomic analyses revealed distinct profiles among the top 100 proteins in the different EVs which may explain these effects: a shared core of 50 immunogenic proteins such as Pgk1, Cdc19, and Fba1; unique, relevant immunogenic proteins in SC5314 YEVs, and proteins linked to pathogenesis, like Ece1 in SC5314 HEVs. Sera from SC5314 YEVs-immunized mice showed the highest IgG2a titers and moderate IL-17, IFN-{gamma}, and TNF- levels, indicating the importance of both humoral and cellular responses for protection. These findings highlight the distinct immunogenic properties of C. albicans EVs, suggesting their potential in acellular vaccine development while emphasizing the need to carefully evaluate pathogenic risks associated with certain EVs.

microbiology↗

bioRxiv2024

Development of optimised human iPSC-derived hepatocytes with improved liver function for in vitro metabolic disease modelling and toxicity studies

Background & AimsLiver disease is a rising cause of mortality worldwide. Primary human hepatocytes (PHH) and hepatocellular cancer cells are currently used in drug development, however, they come with limitations, including limited supply, rapid loss of function, and tumorigenic origin. In addition, current iPSC differentiation protocols lead to the generation of hepatocyte-like cells with compromised liver-related features. We hypothesised that optimisation of iPSC differentiation protocols can lead to the generation of hepatocyte-like cells with improved metabolic functionality for disease modelling and toxicity screening studies. MethodsHealthy human iPSCs were differentiated to hepatocyte-like cells (Opti-HEP) using a novel 3-step differentiation protocol. Hepatocyte functionality was assessed, including liver maturity marker expression, urea synthesis, de novo gluconeogenesis, and CYP450 expression, activity, and induction. Suitability of Opti-HEP to predict drug-induced liver injury (DILI) was evaluated by cell viability assays. CRISPR/Cas9 gene editing was employed to generate in vitro inherited metabolic disease models. ResultsOpti-HEP expressed similar liver maturity marker levels to those seen in primary human hepatocytes (PHH), in addition to functional urea and gluconeogenesis pathways. CYP450 expression and activity were comparable between Opti-HEP and PHH, with both cell types showing similar levels of CYP3A4 induction upon 1,25-hydroxy-vitamin D3 treatment. Opti-HEP accurately predicted DILI, following treatment with 7 drugs of known DILI liability. CRISPR-derived Opti-HEP harbouring mutations for inherited metabolic disorders (Ornithine Transcarbamylase Deficiency, Progressive Familial Intrahepatic Cholestasis Type 2, Citrullinemia Type 1) recapitulated key pathophysiological disease features, including reduced protein expression, impaired urea secretion, and bile acid transport. ConclusionsWe demonstrate the generation of optimised iPSC-derived hepatocytes with enhanced liver functionality that is comparable to PHH. These data alongside the expansion capacity and amenability of these cells highlight the opportunities this model can offer in the space of disease modelling and large-scale drug efficacy and hepatotoxicity screening.

cell biology↗

bioRxiv2023

Unravelling the Role of Candida albicans Prn1 in the Oxidative Stress Response Through a Proteomic Approach

Candida albicans Prn1 is a protein that shares similarities with mammalian Pirin but with an unknown function in the yeast. Orthologues of Prn1 have been identified in other pathogenic fungi but not in Saccharomyces cerevisiae, suggesting a relationship with pathogenesis. Prn1 increase in abundance after H2O2 treatment has been shown previously, thus, in the present work, C. albicans prn1{Delta} mutant and the corresponding wild-type strain SN250 have been treated with H2O2 and their response was studied by quantitative differential proteomics. These assays indicated a lower increase of proteins with oxidoreductase activity after treatment in the prn1{Delta} strain compared to the wild type, as well as an increase in proteasome-activating proteins and a decrease in translation-involved proteins. Accordingly, Prn1 absence, under H2O2 treatment, led to a lower survival rate and a higher percentage of apoptosis, together with higher reactive oxygen species levels and higher proteasome activity. Besides, remarkable differences in the abundance of some transcription factors were observed between the two strains. Mnl1, involved in Prn1 expression, Bas1, Tiff33, and orf19.1150 presented an inverse pattern of expression under H2O2 treatment respect to Nrg1, a Mnl1 antagonist. Interestingly, orf19.4850, a protein orthologue to S. cerevisiae Cub1, has shown to be involved in the response to H2O2 presenting a conserved proteasome function. Under basal conditions, the proteomics results indicate a possible involvement of Prn1 in mitochondrial oxidative stress detoxication. Our experiments confirm Prn1 as a relevant actor in the oxidative response. ImportanceCandida albicans is a human opportunistic pathogen included in the WHO fungal priority pathogens list. The increase in resistant strains necessitates the discovery of new targets for antifungal therapies. Our research sheds light on the important role of the previously uncharacterized C. albicans protein Prn1 during the oxidative stress response. Study of the proteome remodelling under oxidative stress unveils the role of Prn1 in the decreased reactive oxygen species levels and the consequences, such as death by apoptosis and necrosis or cell growth delay. A proteomics approach allowed the identification of several proteins potentially involved in Prn1 activity, such as oxidoreductases and transcription factors. The lack of Prn1 orthologues in Saccharomyces cerevisiae but the presence in other Candida and Aspergillus species implicates this protein in pathogenesis and suggests that it may serve as a candidate for new drug targets.

microbiology↗

bioRxiv2023

Lysosomal MLKL is balanced by ESCRT to control cell death

Mixed lineage kinase-like (MLKL) is activated by RHIM-domain containing kinase (RIPK)3 to permeabilize the plasma-membrane and execute necroptosis, a form of regulated necrosis. We found that MLKL is activated in an atypical, RIPK3- and necroptosis-independent manner downstream of Toll-like receptor 3, resulting in its translocation to lysosomes and lysosomal membrane permeabilization. Damaged lysosomes then undergo exocytosis, leading to the integration of lysosomal MLKL into the plasma-membrane to trigger cell death. The ESCRT-machinery can repair damaged lysosomes and counteract cell death by packing lysosomal MLKL into intraluminal vesicles, which are subsequently released as extracellular vesicles. In this way, ESCRT-machinery balances life and death decisions by preventing lysosomal MLKL to reach its killing destination, which is the plasma-membrane.

cell biology↗

bioRxiv2023

Cross-species comparison of pregnancy-induced GDF15

GDF15 (growth differentiation factor 15) is a stress-induced cytokine. Although the exact physiological function of GDF15 is not yet fully comprehended, the significant elevation of circulating GDF15 levels during gestation suggests a potential role for this hormone in pregnancy. This is corroborated by genetic association studies in which GDF15 and the GDF15 receptor, GDNF Family Receptor Alpha Like (GFRAL) have been linked to morning sickness and hyperemesis gravidarum (HG) in humans. Here, we studied GDF15 biology during pregnancy in mice, rats, macaques, and humans. In contrast to macaques and humans, mice and rats exhibited an underwhelming induction in plasma GDF15 levels in response to pregnancy ([~]75-fold increase in macaques vs. [~]2-fold increase in rodents). The changes in circulating GDF15 levels were corroborated by the magnitude of Gdf15 mRNA and GDF15 protein expression in placentae from mice, rats, and macaques. These species-specific findings may help guide future studies focusing on GDF15 in pregnancy and on the evaluation of pharmacological strategies to interfere with GDF15-GFRAL signaling to treat severe nausea and HG.

physiology↗

bioRxiv2023

CHIR99021 decreases dopamine content in rat brain striatum through inactivation of Tyrosine Hydroxylase

CHIR99021, also known as laduviglusib or CT99021, is a Glycogen-synthase kinase 3{beta} (GSK3{beta}) inhibitor, which has been reported as a promising drug for cardiomyocyte regeneration or treatment of sensorial hearing loss. Since the activation of dopamine (DA) receptors regulates dopamine synthesis and they can signal through the {beta}-arrestin pathway and GSK3{beta}, we decided to check the effect of GSK3{beta} inhibitors (CHIR99021, SB216763 and lithium ion) in the control of DA synthesis. Using ex vivo experiments with minces from rat brain striatum, we observed that CHIR99021, but not SB216763 nor lithium, causes a complete abrogation of DA synthesis and accumulation at low {micro}M concentrations, pointing to off-target effects of CHIR99021. This decrease can be attributed to tyrosine hydroxylase (TH) inhibition since the accumulation of L-DOPA in the presence of a DOPA decarboxylase inhibitor was similarly decreased. On the other hand, CHIR99021 caused a dramatic increase in the DOPAC / DA ratio, an indicator of DA metabolization, and hindered DA incorporation into striatum tissue to the same extent as tetrabenazine, thus pointing to some effect on DA storage that triggers DA feedback inhibition of TH. In addition, CHIR99021 or SB216763, but not lithium, decreased TH phosphorylation in Ser19, but not in Ser31 or Ser40. These results demonstrate that CHIR99021 can lead to TH inactivation and DA depletion in brain striatum, opening the possibility of its use in DA-related disorders, and shows effects to be considered in future clinical trials.

neuroscience↗

bioRxiv2022

Identification of leukemia-associated immunophenotypes by database-guided flow cytometry provides a highly sensitive and reproduciblestrategy for the study of measurable residual disease in acutemyeloblastic leukemia

BackgroundMultiparametric Flow Cytometry (MFC) is an essential tool to study the involved cell lineages, the aberrant differentiation/maturation patterns and the expression of aberrant antigens in acute myeloid leukemia (AML). The characterization of leukemia-associated immunophenotypes (LAIPs) at the moment of diagnosis is critical to establish reproducible strategies for the study of measurable residual disease using MFC (MFC-MRD). MethodsIn this study, we identified and characterized LAIPs by comparing the leukemic populations of 145 AML patients, using the EuroFlow AML/ MDS MFC panel, with 6 databases of normal myeloid progenitors (MPCs). Principal component analysis was used to identify and characterize the LAIPs, which were then used to generate individual profiles for MFC-MRD monitoring. Furthermore, we investigated the relationship between the expression patterns of LAIPs and the different subtypes of AML. The MFC-MRD study was performed by identifying residual AML populations that matched with the LAIPs at diagnosis. To further validate this approach, the presence of MRD was also assessed by qPCR (qPCR-MRD). Finally, we studied the association between MFC-MRD and progression-free survival (PFS). ResultsThe strategy used in this study allowed us to describe more than 300 different LAIPs and facilitated the association of specific phenotypes with certain subtypes of AML. The MFC-MRD monitoring based on LAIPs with good/strong specificity was applicable to virtually all patients and showed a good correlation with qPCR-MRD and PFS. ConclusionsThe described methodology provides an objective method to identify and characterize LAIPs. Furthermore, it provides a theoretical basis to develop highly sensitive MFC-MRD strategies.

cancer biology↗

bioRxiv2022

Statistical evaluation of metaproteomics and 16s rRNA amplicon sequencing techniques for the study of the gut microbiota establishment of infants with cystic fibrosis

The newborn screening for cystic fibrosis (CF) can identify affected but still asymptomatic infants. The selection of omic technique for gut microbiota study is therefore crucial due to both the small amount of feces available and the low microorganism load. Our aim was to compare the agreement between 16S rRNA amplicon sequencing and metaproteomics by a robust statistical analysis including McNemar (taxa presence) test and Bland-Altman (taxa abundance) data plotting for studying the sequential establishment of the gut microbiota during the first year of life in 8 infants with CF (28 fecal samples). The taxonomic assignation was similar by the two techniques, whereas certain discrepancies were observed in the abundance detection, mostly the underrepresentation of Bifidobacterium and the overestimation of certain Firmicutes and Proteobacteria by amplicon sequencing. During the first months of life, the CF gut microbiota is characterized by poor alpha diversity, a significant enrichment of Ruminococcus gnavus, the expression of certain virulent bacterial traits, and the detection of human inflammation-related proteins. Our study provides an extended comparative analysis with robust statistical support that could optimize the use of both approaches for gut microbiota research. Metaproteomics provides information on composition and functionality, as well as data on host-microbiome interactions. Its strength is the identification and quantification of Actinobacteria and certain classes of Firmicutes. Both techniques detected an aberrant microbiota in infants with CF during their first year of life, dominated by the enrichment of R. gnavus within a human inflammatory environment.

microbiology↗

bioRxiv2022

The GDF15-GFRAL pathway is dispensable for the effects of metformin on energy balance

Metformin is a blood glucose lowering medication with physiological effects that extend beyond its anti-diabetic indication. Recently, it was reported that metformin lowers body weight via induction of growth differentiation factor 15 (GDF15), which suppresses food intake by binding to the GDNF family receptor -like (GFRAL) in the hindbrain. At the same time, we demonstrated that recombinant GDF15 suppresses voluntary exercise in a GFRAL-dependent fashion. Here, we corroborate that metformin increases circulating GDF15 in mice and humans, but that it does not reduce voluntary running activity in mice. Unexpectedly, we fail to confirm previous reports that the GDF15-GFRAL pathway is necessary for the weight-lowering effects of metformin. Instead, our studies in wild-type, GDF15 knockout and GFRAL knockout mice suggest that the GDF15-GFRAL pathway is dispensable for the effects of metformin on energy balance. The data presented here question whether metformin is a sufficiently strong stimulator of GDF15 to drive anorexia and weight loss and emphasize that additional work is needed to untangle the relationship among metformin, GDF15 and energy balance.

physiology↗

bioRxiv2021

The structural role of SARS-CoV-2 genetic background in the emergence and success of spike mutations: the case of the spike A222V mutation

The S:A222V point mutation, within the G clade, was characteristic of the 20E (EU1) SARS-CoV-2 variant identified in Spain in early summer 2020. This mutation has now reappeared in the Delta subvariant AY.4.2, raising questions about its specific effect on viral infection. We report combined serological, functional, structural and computational studies characterizing the impact of this mutation. Our results reveal that S:A222V promotes an increased RBD opening and slightly increases ACE2 binding as compared to the parent S:D614G clade. Finally, S:A222V does not reduce sera neutralization capacity, suggesting it does not affect vaccine effectiveness.

molecular biology↗

bioRxiv2021

SARS-CoV-2 Infects Syncytiotrophoblast and Activates Inflammatory Responses in the Placenta

SARS-CoV-2 infection during pregnancy leads to an increased risk of adverse pregnancy outcomes. Although the placenta itself can be a target of virus infection, most neonates are virus free and are born healthy or recover quickly. Here, we investigated the impact of SARS-CoV-2 infection on the placenta from a cohort of women who were infected late during pregnancy and had tested nasal swab positive for SARS-CoV-2 by qRT-PCR at delivery. SARS-CoV-2 genomic and subgenomic RNA was detected in 23 out of 54 placentas. Two placentas with high virus content were obtained from mothers who presented with severe COVID-19 and whose pregnancies resulted in adverse outcomes for the fetuses, including intrauterine fetal demise and a preterm delivered baby still in newborn intensive care. Examination of the placental samples with high virus content showed efficient SARS-CoV-2 infection, using RNA in situ hybridization to detect genomic and replicating viral RNA, and immunohistochemistry to detect SARS-CoV-2 nucleocapsid protein. Infection was restricted to syncytiotrophoblast cells that envelope the fetal chorionic villi and are in direct contact with maternal blood. The infected placentas displayed massive infiltration of maternal immune cells including macrophages into intervillous spaces, potentially contributing to inflammation of the tissue. Ex vivo infection of placental cultures with SARS-CoV-2 or with SARS-CoV-2 spike (S) protein pseudotyped lentivirus targeted mostly syncytiotrophoblast and in rare events endothelial cells. Infection was reduced by using blocking antibodies against ACE2 and against Neuropilin 1, suggesting that SARS-CoV-2 may utilize alternative receptors for entry into placental cells.

cell biology↗

bioRxiv2020

Extending the proteomic characterization of Candida albicans exposed to stress and apoptotic inducers through data-independent acquisition mass spectrometry

Candida albicans is a commensal fungus that causes systemic infections in immunosuppressed patients. In order to deal with the changing environment during commensalism or infection, C. albicans must reprogram its proteome. Characterizing the stress-induced changes in the proteome that C. albicans uses to survive should be very useful in the development of new antifungal drugs. We studied the C. albicans global proteome after exposure to hydrogen peroxide (H2O2) and acetic acid (AA), using a DIA-MS strategy. More than 2000 C. albicans proteins were quantified using an ion library previously constructed using DDA-MS. C. albicans responded to treatment with H2O2 with an increase in the abundance of many proteins involved in the oxidative stress response, protein folding and proteasome-dependent catabolism, which led to an increased proteasome activity. The data revealed a previously unknown key role for Prn1, a protein similar to pirins, in the oxidative stress response. Treatment with AA resulted in a general decrease in the abundance of proteins involved in amino acid biosynthesis, protein folding, and rRNA processing. Almost all proteasome proteins declined, as did proteasome activity. Apoptosis was observed after treatment with H2O2, but not AA. A targeted proteomic study of 32 proteins related to apoptosis in yeast supported the results found by DIA-MS and allowed the creation of an efficient method to quantify relevant proteins after treatment with stressors (H2O2, AA, and amphotericin B). This approach also uncovered a main role for Oye32, an oxidoreductase, suggesting this protein as a possible apoptotic marker common to many stressors. IMPORTANCEFungal infections are a worldwide health problem especially in immunocompromised patients and patients with chronic disorders. Invasive candidiasis, mainly caused by C. albicans, are among the most common fungal diseases. Despite the existence of treatments to combat candidiasis the spectra of drugs available are limited. For the discovery of new drug targets is essential to know the pathogen response to different stress conditions. Our study provides a global vision of proteomic remodeling in C. albicans after exposure to different agents such as hydrogen peroxide, acetic acid and amphotericin B that can cause apoptotic cell death. This results revealed the significance of many proteins related to oxidative stress response and proteasome activity among others. Of note, the discovery of Prn1 as a key protein in the defence against oxidative stress as well the increase in the abundance of Oye32 protein when apoptotic process occurred point out them as possible drug targets.

microbiology↗