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The zinc restriction and zinc toxicity are part of host defence, called nutritional immunity. The crucial role of zinc homeostasis in microbial survival within a host is established, but little is known about these processes in the opportunistic human fungal pathogen Candida parapsilosis. Our in silico predictions suggested the presence of at least six potential zinc transporters (ZnTs) in C. parapsilosis —orthologues of ZRC1 , ZRT3 and ZRT101 —but an orthologue of PRA1 zincophore was not found. In addition, we detected a species-specific gene expansion of the novel ZnT ZRT2, as we identified three orthologue genes in the genome of C. parapsilosis . Based on predictions, we created homozygous mutant strains of the potential ZnTs and characterized them. Despite the apparent gene expansion of ZRT2 in C. parapsilosis , only CpZRT21 was essential for growth in a zinc-depleted acidic environment, in addition we found that CpZrc1 is essential for zinc detoxification and also protects the fungi against the elimination of murine macrophages. Significantly, we demonstrated that C. parapsilosis forms zincosomes in a Zrc1-independent manner and zinc detoxification is mediated by the vacuolar importer CpZrc1. Our study defines the functions of C. parapsilosis ZnTs, including a species-specific survival and zinc detoxification system.

Candida parapsilosis is a leading cause of invasive mycoses and the major cause of nosocomial fungaemia amongst low and very low birth weight neonates. However, the molecular and physiological characteristics of this fungus remain understudied. To advance our knowledge about the pathobiology of this pathogen, we sought to develop and validate an effective method for chemical transformation of C. parapsilosis. Chemical transformation is the primary procedure for introducing foreign DNA into Candida yeast as it requires no special equipment, although its performance efficacy drops rapidly when the size of the transforming DNA increases. To define optimal conditions for chemical transformation in C. parapsilosis, we selected a leucine auxotroph laboratory strain. We identified optimal cell density for transformation, incubation times, inclusion of specific enhancing chemicals, and size and amounts of DNA fragments that resulted in maximized transformation efficiency. We determined that the inclusion of dimethyl sulfoxide was beneficial, but dithiothreitol pretreatment reduced colony recovery. As a result, the modified protocol led to a 20–55-fold increase in transformation efficiency, depending on the size of the transforming fragment. We validated the modified methodology with prototrophic isolates and demonstrated that the new approach resulted in the recovery of significantly more transformants in 5 of 6 isolates. Additionally, we identified a medium in which transformation competent yeast cells could safely be maintained at −80°C for up to 6 weeks that reduces laboratory work and shortens the overall procedure. These modifications will significantly aid further investigations into the genetic basis for virulence in C. parapsilosis.

Global burden associated with the growing incidence of fungal infections poses as a serious threat especially in developing countries. Several local surveillance programs have already been established to follow the epidemiological characteristics of Candida infections; however, these programs often only focused on broadly researched regions, like Europe, North America, and certain Asian countries. Therefore, the need to evaluate epidemiological data is high in less studied regions, for example in the tropical climate zone countries, especially since the number of fungal infections is generally described to be higher in these locations. C. albicans is still the most often isolated pathogenic species, in the Candida genus; however, the importance of other NAC (non-albicans Candida species) is increasing. Distributions of frequently isolated Candida species known to differ according to climate zones. For instance, Northern Europe and the USA generally report C. glabrata as the most prominent NAC species, while C. tropicalis-associated infections are more common in tropical regions. Current epidemiological data from tropic regions highlights the importance to study Candida-associated fungal infections in these locations, since besides the most common pathogens, emerging species like C. auris appearing to become more frequently isolated.

In recent years, the relevance of diseases associated with fungal pathogens increased worldwide. Members of the Candida genus are responsible for the greatest number of fungal bloodstream infections every year. Epidemiological data consistently indicate a modest shift toward non-albicans species, albeit Candidaalbicans is still the most recognizable species within the genus. As a result, the number of clinically relevant pathogens has increased, and, despite their distinct pathogenicity features, the applicable antifungal agents remained the same. For bloodstream infections, only three classes of drugs are routinely used, namely polyenes, azoles and echinocandins. Antifungal resistance toward all three antifungal drug classes frequently occurs in clinical settings. Compared with the broad range of literature on virulence and antifungal resistance of Candida species separately, only a small portion of studies examined the effect of resistance on virulence. These studies found that resistance to polyenes and echinocandins concluded in significant decrease in the virulence in different Candida species. Meanwhile, in some cases, resistance to azole type antifungals resulted in increased virulence depending on the species and isolates. These findings underline the importance of studies aiming to dissect the connections of virulence and resistance in Candida species.

Major depressive disorder is a severe illness that frequently manifests before the age of 18 years, often recurring later in life. Paediatric medical treatment options are scarce. The melatonin receptor agonist and 5-hydroxytryptamineWe performed a 12 week, randomised, double-blind, parallel-group, multicentre, phase 3 trial in 46 specialist psychiatric units or centres in Bulgaria, Finland, Hungary, Poland, Romania, Russia, Serbia, South Africa, and Ukraine. Participants (aged 7-17 years) were eligible if they were unresponsive to psychosocial therapy during the 3-week run-in period (Children's Depression Rating Scale-revised [CDRS-R] score of ≥45). Ethnicity was not recorded. We investigated short-term antidepressant efficacy of agomelatine (10 mg or 25 mg per day) versus placebo with an active control (fluoxetine 10-20 mg depending on symptom severity) after 12 weeks of treatment in children (aged 7-11 years) and adolescents (12-17 years) with major depressive disorder. Patients were randomly assigned (1:1:1:1) to agomelatine 10 mg, agomelatine 25 mg, placebo, or fluoxetine via an interactive response system with permuted-block randomisation. Standardised manualised psychosocial counselling, developed for this trial, was initiated from selection and continued throughout the study, including the open-label extension. All people involved in the conduct of the clinical trial and patients were masked to treatment allocation. Study outcomes were measured using standardised interviews at each study visit. The primary endpoint was change in CDRS-R raw score from baseline to week 12. This study is registered with EudraCT, 2015-002181-23.Between Feb 23, 2016, and Jan 14, 2020, 466 individuals were assessed for eligibility and of 400 included patients, 396 (247 [62%] girls, 149 [38%] boys; mean age 13·7 years [SD 2·7]) were analysed (full analysis set). The primary objective was met; 25 mg/day agomelatine (n=94, with n=102 receiving 10 mg/day) resulted in an improvement versus placebo (n=101) in CDRS-R raw score of 4·22 (95% CI 0·63-7·82; p=0·040) at 12 weeks, with a similar effect for fluoxetine (n=99), establishing assay sensitivity. The overall effect was confirmed in adolescents (n=317), but not in children (n=79). No unexpected safety signals were observed with agomelatine, with no significant weight gain or effect on suicidal behaviours.This first study in a paediatric population supports the efficacy of 25 mg/day agomelatine, in addition to psychosocial counselling, in treating adolescent patients with major depressive disorder, with no unexpected safety signals. This medication could provide another option in the limited psychopharmaceutical repertoire for management of major depressive disorder.Servier. VIDEO ABSTRACT.

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Nóra Igaz,1 Péter Bélteky,2 Dávid Kovács,1,3 Csaba Papp,4 Andrea Rónavári,2 Diána Szabó,5 Attila Gácser,4 Zoltán Kónya,2,6 Mónika Kiricsi1 1Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary; 2Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary; 3Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d’Azur, Inserm, CNRS, Valbonne, France; 4HCEMM-USZ Fungal Pathogens Research Group, Department of Microbiology, University of Szeged, Szeged, Hungary; 5Department of Oto-Rhino-Laryngology and Head & Neck Surgery, Szeged, Hungary; 6Eötvös Loránd Research Network, Reaction Kinetics and Surface Chemistry Research Group, Szeged, HungaryCorrespondence: Mónika Kiricsi, Department of Biochemistry and Molecular Biology, University of Szeged, Közép fasor 52, Szeged, H-6726, Hungary, Tel +36 (62) 544-887, Email kiricsim@bio.u-szeged.hu Zoltán Kónya, Department of Applied and Environmental Chemistry, University of Szeged, Rerrich square 1, Szeged, H-6720, Hungary, Tel +36 (62) 544620, Email konya@chem.u-szeged.huBackground: Multidrug resistance is a common reason behind the failure of chemotherapy. Even if the therapy is effective, serious adverse effects might develop due to the low specificity and selectivity of antineoplastic agents. Mesoporous silica nanoparticles (MSNs) are promising materials for tumor-targeting and drug-delivery due to their small size, relatively inert nature, and extremely large specific surfaces that can be functionalized by therapeutic and targeting entities. We aimed to create a fluorescently labeled MSN-based drug-delivery system and investigate their internalization and drug-releasing capability in drug-sensitive MCF-7 and P-glycoprotein-overexpressing multidrug-resistant MCF-7 KCR cancer cells.Methods and Results: To track the uptake and subcellular distribution of MSNs, particles with covalently coupled red fluorescent Rhodamine B (RhoB) were produced (RhoB@MSNs). Both MCF-7 and MCF-7 KCR cells accumulated a significant amount of RhoB@MSNs. The intracellular RhoB@MSN concentrations did not differ between sensitive and multidrug-resistant cells and were kept at the same level even after cessation of RhoB@MSN exposure. Although most RhoB@MSNs resided in the cytoplasm, significantly more RhoB@MSNs co-localized with lysosomes in multidrug-resistant cells compared to sensitive counterparts. To examine the drug-delivery capability of these particles, RhoB@Rho123@MSNs were established, where RhoB-functionalized nanoparticles carried green fluorescent Rhodamine 123 (Rho123) - a P-glycoprotein substrate – as cargo within mesopores. Significantly higher Rho123 fluorescence intensity was detected in RhoB@Rho123@MSN-treated multidrug-resistant cells than in free Rho123-exposed counterparts. The exceptional drug-delivery potential of MSNs was further verified using Mitomycin C (MMC)-loaded RhoB@MSNs (RhoB@MMC@MSNs). Exposures to RhoB@MMC@MSNs significantly decreased the viability not only of drug-sensitive but of multidrug-resistant cells and the elimination of MDR cells was significantly more robust than upon free MMC treatments.Conclusion: The efficient delivery of Rho123 and MMC to multidrug-resistant cells via MSNs, the amplified and presumably prolonged intracellular drug concentration, and the consequently enhanced cytotoxic effects envision the enormous potential of MSNs to defeat multidrug-resistant cancer.Graphical Abstract: Keywords: mesoporous silica nanoparticles, drug-delivery, fluorescently labeled MSNs, functionalized MSNs, multidrug resistance

Our skin provides immunological protection against several pathogens. Skin epithelial cells respond to microbial stimuli in various ways, such as through the production of antimicrobial peptides or secretion of cytokines, although phagocytosis of potentially evading microbes was also reported. Relatively little is known about how skin keratinocytes differentiate between the presence of pathogenic and commensal fungi. In this project, we aimed to investigate how human keratinocytes interact with different Candida species, as common colonizers of the skin. While C. albicans is a common cause of cutaneous candidiasis, C. parapsilosisis rarely associated with this disease.For the experimentshuman skin keratinocyte cell lines (HaCaT, HPV-KER)were applied andchallengedwith C. albicans (SC5314 and WO1 strains) and C. parapsilosis (GA1 and CLIB214 strains)strains.We aimedto determine the extent to which C. albicans and C. parapsilosis damage human keratinocytes, their attachment to host cells, the keratinocytes’ ability to internalize these fungi and to examinecytokine production in response to stimuli. Our results suggest that C. albicans causes significantly more damage to human keratinocytes than C. parapsilosis and the HPV-KER cell line was more susceptibleto the infection. In both HaCaT and HPV-KER cells, the production of IL-6, IL-8, and CCL5 increased primarilyafter C. albicans infection. Based on the adhesion studies, there was a low degree of association in case of C. parapsilosis GA1 and CLIB214 compared to C. albicans SC5314 and WO1.

The pathophysiology of acute pancreatitis (AP) is not well understood, and the disease does not have specific therapy. Tryptophan metabolite L-kynurenic acid (KYNA) and its synthetic analogue SZR-72 are antagonists of the N-methyl-D-aspartate receptor (NMDAR) and have immune modulatory roles in several inflammatory diseases. Our aims were to investigate the effects of KYNA and SZR-72 on experimental AP and to reveal their possible mode of action. AP was induced by intraperitoneal (i.p.) injection of L-ornithine-HCl (LO) in SPRD rats. Animals were pretreated with 75-300 mg/kg KYNA or SZR-72. Control animals were injected with physiological saline instead of LO, KYNA and/or SZR-72. Laboratory and histological parameters, as well as pancreatic and systemic circulation were measured to evaluate AP severity. Pancreatic heat shock protein-72 and IL-1β were measured by western blot and ELISA, respectively. Pancreatic expression of NMDAR1 was investigated by RT-PCR and immunohistochemistry. Viability of isolated pancreatic acinar cells in response to LO, KYNA, SZR-72 and/or NMDA administration was assessed by propidium-iodide assay. The effects of LO and/or SZR-72 on neutrophil granulocyte function was also studied. Almost all investigated laboratory and histological parameters of AP were significantly reduced by administration of 300 mg/kg KYNA or SZR-72, whereas the 150 mg/kg or 75 mg/kg doses were less or not effective, respectively. The decreased pancreatic microcirculation was also improved in the AP groups treated with 300 mg/kg KYNA or SZR-72. Interestingly, pancreatic heat shock protein-72 expression was significantly increased by administration of SZR-72, KYNA and/or LO. mRNA and protein expression of NMDAR1 was detected in pancreatic tissue. LO treatment caused acinar cell toxicity which was reversed by 250 µM KYNA or SZR-72. Treatment of acini with NMDA (25, 250, 2000 µM) did not influence the effects of KYNA or SZR-72. Moreover, SZR-72 reduced LO-induced H2O2 production of neutrophil granulocytes. KYNA and SZR-72 have dose-dependent protective effects on LO-induced AP or acinar toxicity which seem to be independent of pancreatic NMDA receptors. Furthermore, SZR-72 treatment suppressed AP-induced activation of neutrophil granulocytes. This study suggests that administration of KYNA and its derivative could be beneficial in AP.

Predatory interactions among microbes are major evolutionary driving forces for biodiversity. The fungivorous amoeba Protostelium aurantium has a wide fungal food spectrum including foremost pathogenic members of the genus Candida. Here we show that upon phagocytic ingestion by the amoeba, Candida parapsilosis is confronted with an oxidative burst and undergoes lysis within minutes of processing in acidified phagolysosomes. On the fungal side, a functional genomic approach identified copper and redox homeostasis as primary targets of amoeba predation, with the highly expressed copper exporter gene CRP1 and the peroxiredoxin gene PRX1 contributing to survival when encountered with P. aurantium. The fungicidal activity was largely retained in intracellular vesicles of the amoebae. Following their isolation, the content of these vesicles induced immediate killing and lysis of C. parapsilosis in vitro. Proteomic analysis identified 56 vesicular proteins from P. aurantium. Although completely unknown proteins were dominant, many of them could be categorised as hydrolytic enzymes targeting the fungal cell wall, indicating that fungal cell wall structures are under selection pressure by predatory phagocytes in natural environments. TAKE AWAY: The amoeba Protostelium aurantium feeds on fungi, such as Candida parapsilosis. Ingested yeast cells are exposed to reactive oxygen species. A copper exporter and a peroxiredoxin contribute to fungal defence. Yeast cells undergo intracellular lysis. Lysis occurs via a cocktail of hydrolytic enzymes from intracellular vesicles.

Many fungal species utilize hydroxyderivatives of benzene and benzoic acid as carbon sources. The yeast Candida parapsilosis metabolizes these compounds via the 3-oxoadipate and gentisate pathways, whose components are encoded by two metabolic gene clusters. In this study, we determine the chromosome level assembly of the C. parapsilosis strain CLIB214 and use it for transcriptomic and proteomic investigation of cells cultivated on hydroxyaromatic substrates. We demonstrate that the genes coding for enzymes and plasma membrane transporters involved in the 3-oxoadipate and gentisate pathways are highly upregulated and their expression is controlled in a substrate-specific manner. However, regulatory proteins involved in this process are not known. Using the knockout mutants, we show that putative transcriptional factors encoded by the genes OTF1 and GTF1 located within these gene clusters function as transcriptional activators of the 3-oxoadipate and gentisate pathway, respectively. We also show that the activation of both pathways is accompanied by upregulation of genes for the enzymes involved in β-oxidation of fatty acids, glyoxylate cycle, amino acid metabolism, and peroxisome biogenesis. Transcriptome and proteome profiles of the cells grown on 4-hydroxybenzoate and 3-hydroxybenzoate, which are metabolized via the 3-oxoadipate and gentisate pathway, respectively, reflect their different connection to central metabolism. Yet we find that the expression profiles differ also in the cells assimilating 4-hydroxybenzoate and hydroquinone, which are both metabolized in the same pathway. This finding is consistent with the phenotype of the Otf1p-lacking mutant, which exhibits impaired growth on hydroxybenzoates, but still utilizes hydroxybenzenes, thus indicating that additional, yet unidentified transcription factor could be involved in the 3-oxoadipate pathway regulation. Moreover, we propose that bicarbonate ions resulting from decarboxylation of hydroxybenzoates also contribute to differences in the cell responses to hydroxybenzoates and hydroxybenzenes. Finally, our phylogenetic analysis highlights evolutionary paths leading to metabolic adaptations of yeast cells assimilating hydroxyaromatic substrates.Author summaryBenzene and its derivatives are simple aromatic compounds representing key substances for the chemical industry. While benzene itself is toxic and carcinogenic, benzoic acid is commonly used in the food industry and some of its derivatives are used in pharmacology (aspirin) or cosmetics (parabens). The benzene ring of aromatic molecules is relatively stable, but many microorganisms including yeasts break it enzymatically and, in a series of biochemical reactions, utilize resulting metabolites as carbon sources. Understanding the genetic basis of corresponding metabolic pathways and their regulation opens a venue for applications in biotechnology and bioremediation of polluted environments. Here we investigate the yeast Candida parapsilosis which assimilates various hydroxybenzenes and hydroxybenzoates via the 3-oxoadipate and gentisate pathways. We show that the genes coding for the substrate transporters and enzymes involved in both pathways are co-expressed and regulated by the transcriptional activators Otf1p and Gtf1p, respectively. Our results also reveal the connections of both pathways to central metabolism and organelle biogenesis and provide an insight into evolution of metabolism of hydroxyaromatic compounds.

Several strikingly different aerobic and anaerobic pathways of nicotinate breakdown are extant in bacteria. Here, through reverse genetics and analytical techniques we elucidated in Aspergillus nidulans, a complete eukaryotic nicotinate utilization pathway. The pathway extant in this fungus and other ascomycetes, is quite different from bacterial ones. All intermediate metabolites were identified. The cognate proteins, encoded by eleven genes (hxn) mapping in three clusters are co-regulated by a specific transcription factor. Several enzymatic steps have no prokaryotic equivalent and two metabolites, 3-hydroxypiperidine-2,6-dione and 5,6-dihydroxypiperidine-2-one, have not been identified previously in any organism, the latter being a novel chemical compound. Hydrolytic ring opening results in α-hydroxyglutaramate, a compound not detected in analogous prokaryotic pathways. Our earlier phylogenetic analysis of Hxn proteins together with this complete biochemical pathway illustrates convergent evolution of catabolic pathways between fungi and bacteria.

Saccharomyces yeast probiotics (S. ‘boulardii’) have long been applied in the treatment of several gastrointestinal conditions. Despite their widespread use, they are rare opportunistic pathogens responsible for a high proportion of Saccharomyces mycosis cases. The potential virulence attributes of S. ‘boulardii’ as well as its interactions with the human immune system have been studied, however, no information is available on how these yeasts may change due to in-host evolution. To fill this gap, we compared the general phenotypic characteristics, cell morphology, virulence factors, epithelial and immunological interactions, and pathogenicity of four probiotic product samples, two mycosis, and eight non-mycosis samples of S. ‘boulardii’. We assessed the characteristics related to major steps of yeast infections. Mycosis and non-mycosis isolates both displayed novel characters when compared to the product isolates, but in the case of most virulence factors and in pathogenicity, differences were negligible or, surprisingly, the yeasts from products showed elevated levels. No isolates inflicted considerable damage to the epithelial model or bore the hallmarks of immune evasion. Our results show that strains in probiotic products possess characteristics that enable them to act as pathogens upon permissive conditions, and their entry into the bloodstream is not due to active mechanisms but depends on the host. Survival in the host is dependent on yeast phenotypic characteristics which may change in many ways once they start evolving in the host. These facts call attention to the shortcomings of virulence phenotyping in yeast research, and the need for a more thorough assessment of probiotic use.

The spleen tyrosine kinase (Syk) and the downstream adaptor protein CARD9 are crucial signaling molecules in antimicrobial immunity. Candida parapsilosis is an emerging fungal pathogen with a high incidence in neonates, while Candida albicans is the most common agent of candidiasis. While signaling through Syk/CARD9 promotes protective host mechanisms in response to C. albicans, its function in immunity against C. parapsilosis remains unclear. Here, we generated Syk−/− and CARD9−/− bone marrow chimeric mice to study the role of Syk/CARD9 signaling in immune responses to C. parapsilosis compared to C. albicans. We demonstrate various functions of this pathway (e.g., phagocytosis, phagosome acidification, and killing) in Candida-challenged, bone marrow-derived macrophages with differential involvement of Syk and CARD9 along with species-specific differences in cytokine production. We report that Syk−/− or CARD9−/− chimeras rapidly display high susceptibility to C. albicans, while C. parapsilosis infection exacerbates over a prolonged period in these animals. Thus, our results establish that Syk and CARD9 contribute to systemic resistance to C. parapsilosis and C. albicans differently. Additionally, we confirm prior studies but also detail new insights into the fundamental roles of both proteins in immunity against C. albicans. Our data further suggest that Syk has a more prominent influence on anti-Candida immunity than CARD9. Therefore, this study reinforces the Syk/CARD9 pathway as a potential target for anti-Candida immune therapy. IMPORTANCE While C. albicans remains the most clinically significant Candida species, C. parapsilosis is an emerging pathogen with increased affinity to neonates. Syk/CARD9 signaling is crucial in immunity to C. albicans, but its role in in vivo responses to other pathogenic Candida species is largely unexplored. We used mice with hematopoietic systems deficient in Syk or CARD9 to comparatively study the function of these proteins in anti-Candida immunity. We demonstrate that Syk/CARD9 signaling has a protective role against C. parapsilosis differently than against C. albicans. Thus, this study is the first to reveal that Syk can exert immune responses during systemic Candida infections species specifically. Additionally, Syk-dependent immunity to a nonalbicans Candida species in an in vivo murine model has not been reported previously. We highlight that the contribution of Syk and CARD9 to fungal infections are not identical and underline this pathway as a promising immune-therapeutic target to fight Candida infections.

Publisher Copyright: Copyright © 2021 Horváth et al. Oral epithelial cells monitor microbiome composition and initiate immune response upon dysbiosis, as in the case of Candida imbalances. Candida species, such as C. albicans and C. parapsilosis, are the most prevalent yeasts in the oral cavity. Comparison of healthy oral epithelial cell responses revealed that while C. albicans infection robustly activated inflammation cascades, C. parapsilosis primarily activated various inflammation-independent pathways. In posttranscriptional regulatory processes, several miRNAs were altered by both species. For C. parapsilosis, the dose of yeast cells directly correlated with changes in transcriptomic responses with higher fungal burdens inducing significantly different and broader changes. MicroRNAs (miRNAs) associated with carbohydrate metabolism-, hypoxia-, and vascular development-related responses dominated with C. parapsilosis infection, whereas C. albicans altered miRNAs linked to inflammatory responses. Subsequent analyses of hypoxia-inducible factor 1a (HIF1-a) and hepatic stellate cell (HSC) activation pathways predicted target genes through which miRNA-dependent regulation of yeast-specific functions may occur, which also supported the observed species-specific responses. Our findings suggest that C. parapsilosis is recognized as a commensal at low doses by the oral epithelium; however, increased fungal burden activates different pathways, some of which overlap with the inflammatory processes robustly induced by C. albicans. IMPORTANCE A relatively new topic within the field of immunology involves the role of miRNAs in innate as well as adaptive immune response regulation. In recent years, posttranscriptional regulation of host-pathogenic fungal interactions through miRNAs was also suggested. Our study reveals that the distinct nature of human oral epithelial cell responses toward C. parapsilosis and C. albicans is possibly due to species-specific fine-tuning of host miRNA regulatory processes. The findings of this study also shed new light on the nature of early host cell transcriptional responses to the presence of C. parapsilosis and highlight the species’ potential inflammation-independent host activation processes. These findings contribute to our better understanding of how miRNA deregulation at the oral immunological barrier, in non-canonical immune cells, may discriminate between fungal species, particularly Candida species with high or low pathogenic potential.

The 3-oxoacyl-CoA thiolases catalyze the last step of the fatty acid β-oxidation pathway. In yeasts and plants, this pathway takes place exclusively in peroxisomes, whereas in animals it occurs in both peroxisomes and mitochondria. In contrast to baker's yeast Saccharomyces cerevisiae, yeast species from the Debaryomycetaceae family also encode a thiolase with predicted mitochondrial localization. These yeasts are able to utilize a range of hydroxyaromatic compounds via the 3-oxoadipate pathway the last step of which is catalyzed by 3-oxoadipyl-CoA thiolase and presumably occurs in mitochondria. In this work, we studied Oct1p, an ortholog of this enzyme from Candida parapsilosis. We found that the cells grown on a 3-oxoadipate pathway substrate exhibit increased levels of the OCT1 mRNA. Deletion of both OCT1 alleles impairs the growth of C. parapsilosis cells on 3-oxoadipate pathway substrates and this defect can be rescued by expression of the OCT1 gene from a plasmid vector. Subcellular localization experiments and LC-MS/MS analysis of enriched organellar fraction-proteins confirmed the presence of Oct1p in mitochondria. Phylogenetic profiling of Oct1p revealed an intricate evolutionary pattern indicating multiple horizontal gene transfers among different fungal groups.