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Nature Nov 2023Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model. Recently, the clinically vital...
Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model. Recently, the clinically vital but also highly renal-toxic small-molecule natural product amphotericin B was instead found to kill fungi primarily by forming extramembraneous sponge-like aggregates that extract ergosterol from lipid bilayers. Here we show that rapid and selective extraction of fungal ergosterol can yield potent and renal-sparing polyene antifungals. Cholesterol extraction was found to drive the toxicity of amphotericin B to human renal cells. Our examination of high-resolution structures of amphotericin B sponges in sterol-free and sterol-bound states guided us to a promising structural derivative that does not bind cholesterol and is thus renal sparing. This derivative was also less potent because it extracts ergosterol more slowly. Selective acceleration of ergosterol extraction with a second structural modification yielded a new polyene, AM-2-19, that is renal sparing in mice and primary human renal cells, potent against hundreds of pathogenic fungal strains, resistance evasive following serial passage in vitro and highly efficacious in animal models of invasive fungal infections. Thus, rational tuning of the dynamics of interactions between small molecules may lead to better treatments for fungal infections that still kill millions of people annually and potentially other resistance-evasive antimicrobials, including those that have recently been shown to operate through supramolecular structures that target specific lipids.
Topics: Animals; Humans; Mice; Amphotericin B; Antifungal Agents; Cells, Cultured; Cholesterol; Drug Resistance, Fungal; Ergosterol; Kidney; Kinetics; Microbial Sensitivity Tests; Mycoses; Polyenes; Serial Passage; Sterols; Time Factors
PubMed: 37938782
DOI: 10.1038/s41586-023-06710-4 -
Nature Communications Oct 2023Sphingolipids are structural membrane components that also function in cellular stress responses. The serine palmitoyltransferase (SPT) catalyzes the rate-limiting step...
Sphingolipids are structural membrane components that also function in cellular stress responses. The serine palmitoyltransferase (SPT) catalyzes the rate-limiting step in sphingolipid biogenesis. Its activity is tightly regulated through multiple binding partners, including Tsc3, Orm proteins, ceramides, and the phosphatidylinositol-4-phosphate (PI4P) phosphatase Sac1. The structural organization and regulatory mechanisms of this complex are not yet understood. Here, we report the high-resolution cryo-EM structures of the yeast SPT in complex with Tsc3 and Orm1 (SPOT) as dimers and monomers and a monomeric complex further carrying Sac1 (SPOTS). In all complexes, the tight interaction of the downstream metabolite ceramide and Orm1 reveals the ceramide-dependent inhibition. Additionally, observation of ceramide and ergosterol binding suggests a co-regulation of sphingolipid biogenesis and sterol metabolism within the SPOTS complex.
Topics: Ceramides; Sphingolipids; Proteins; Saccharomyces cerevisiae; Serine C-Palmitoyltransferase; Saccharomyces cerevisiae Proteins
PubMed: 37794019
DOI: 10.1038/s41467-023-41747-z -
MBio Aug 2023Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been...
Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been well defined in model yeast, little is known about sterol organization in the context of fungal pathogenesis. We identified a retrograde sterol transporter, Ysp2, in the opportunistic fungal pathogen . We found that the lack of Ysp2 under host-mimicking conditions leads to abnormal accumulation of ergosterol at the plasma membrane, invagination of the plasma membrane, and malformation of the cell wall, which can be functionally rescued by inhibiting ergosterol synthesis with the antifungal drug fluconazole. We also observed that cells lacking Ysp2 mislocalize the cell surface protein Pma1 and have abnormally thin and permeable capsules. As a result of perturbed ergosterol distribution and its consequences, ∆ cells cannot survive in physiologically relevant environments such as host phagocytes and are dramatically attenuated in virulence. These findings expand our knowledge of cryptococcal biology and underscore the importance of sterol homeostasis in fungal pathogenesis. IMPORTANCE is an opportunistic fungal pathogen that kills over 100,000 people worldwide each year. Only three drugs are available to treat cryptococcosis, and these are variously limited by toxicity, availability, cost, and resistance. Ergosterol is the most abundant sterol in fungi and a key component in modulating membrane behavior. Two of the drugs used for cryptococcal infection, amphotericin B and fluconazole, target this lipid and its synthesis, highlighting its importance as a therapeutic target. We discovered a cryptococcal ergosterol transporter, Ysp2, and demonstrated its key roles in multiple aspects of cryptococcal biology and pathogenesis. These studies demonstrate the role of ergosterol homeostasis in virulence, deepen our understanding of a pathway with proven therapeutic importance, and open a new area of study.
Topics: Humans; Virulence; Ergosterol; Fluconazole; Cryptococcosis; Cryptococcus neoformans; Antifungal Agents; Saccharomyces cerevisiae; Sterols; Membrane Transport Proteins; Fungal Proteins
PubMed: 37409809
DOI: 10.1128/mbio.01353-23 -
Cells Nov 2023Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic species have evolved intrinsic and... (Review)
Review
Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: and ; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent species. Notably, , and demonstrate fluconazole resistance.
Topics: Antifungal Agents; Candida; Fluconazole; Echinocandins; Azoles
PubMed: 37998390
DOI: 10.3390/cells12222655 -
International Journal of Molecular... Dec 2023Withaferin A (WA) and celastrol (CEL) are major bioactive components of plants that have been widely employed in traditional medicine. The pleiotropic activities of... (Review)
Review
Withaferin A (WA) and celastrol (CEL) are major bioactive components of plants that have been widely employed in traditional medicine. The pleiotropic activities of plant preparations and the isolated compounds in vitro and in vivo have been documented in hundreds of studies. Both WA and CEL were shown to have anticancer activity. Although WA and CEL belong to different chemical classes, our synthesis of the available information suggests that the compounds share basic mechanisms of action. Both WA and CEL bind covalently to numerous proteins, causing the partial unfolding of some of these proteins and of many bystander proteins. The resulting proteotoxic stress, when excessive, leads to cell death. Both WA and CEL trigger the activation of the unfolded protein response (UPR) which, if the proteotoxic stress persists, results in apoptosis mediated by the PERK/eIF-2/ATF4/CHOP pathway or another UPR-dependent pathway. Other mechanisms of cell death may play contributory or even dominant roles depending on cell type. As shown in a proteomic study with WA, the compounds appear to function largely as electrophilic reactants, indiscriminately modifying reachable nucleophilic amino acid side chains of proteins. However, a remarkable degree of target specificity is imparted by the cellular context.
Topics: Proteostasis; Proteomics; Pentacyclic Triterpenes; Withanolides
PubMed: 38203539
DOI: 10.3390/ijms25010367 -
BioRxiv : the Preprint Server For... Aug 2023Ergosterol is a critical component of fungal plasma membranes. Although many currently available antifungal compounds target the ergosterol biosynthesis pathway for...
Ergosterol is a critical component of fungal plasma membranes. Although many currently available antifungal compounds target the ergosterol biosynthesis pathway for antifungal effect, current knowledge regarding ergosterol synthesis remains incomplete for filamentous fungal pathogens like . Here, we show for the first time that the lipid droplet-associated sterol C-24 methyltransferase, Erg6, is essential for viability. We further show that this essentiality extends to additional species, including and . Neither the overexpression of a putative paralog, nor the exogenous addition of ergosterol could rescue deficiency. Importantly, Erg6 downregulation results in a dramatic decrease in ergosterol and accumulation in lanosterol and is further characterized by diminished sterol-rich plasma membrane domains (SRDs) at hyphal tips. Unexpectedly, repressed strains demonstrate wild-type susceptibility against the ergosterol-active triazole and polyene antifungals. Finally, repressing expression reduced fungal burden accumulation in a murine model of invasive aspergillosis. Taken together, our studies suggest that Erg6, which shows little homology to mammalian proteins, is potentially an attractive antifungal drug target for therapy of infections.
PubMed: 37609350
DOI: 10.1101/2023.08.08.552489 -
The Journal of Steroid Biochemistry and... Oct 2023Lumisterol (L2) is a photoproduct of UVB action on the fungal membrane sterol, ergosterol. Like vitamin D, it is present in edible mushrooms, especially after UV...
Lumisterol (L2) is a photoproduct of UVB action on the fungal membrane sterol, ergosterol. Like vitamin D, it is present in edible mushrooms, especially after UV irradiation. Lumisterol is similarly produced in human skin from 7-dehydrocholesterol by UVB and can be converted to hydroxy-metabolites by CYP27A1 and CYP11A1. These products are biologically active on human cells with actions that include photoprotection and inhibition of proliferation. The aim of this study was to test the ability of CYP11A1 and CYP27A1 to metabolise L2. Purified CYP27A1 was found to efficiently metabolise L2 to three major products and several minor products, whilst CYP11A1 did not act appreciably on L2. The three major products of CYP27A1 action on L2 were identified by mass spectrometry and NMR as 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2. Minor products included two dihydroxy L2 species, one which was identified as 24,27(OH)L2, and another metabolite with one oxo and one hydroxyl group added. A comparison on the kinetics of the metabolism of L2 by CYP27A1 with that of the structurally similar compounds, L3 and ergosterol, was carried out with substrates incorporated into phospholipid vesicles. CYP27A1 displayed a 12-fold lower K with L2 as substrate compared to L3 and a 5-fold lower turnover number (k), resulting in a 2.2 fold higher catalytic efficiency (k/K) for L2 metabolism. L2 was a much better substrate for CYP27A1 than its precursor, ergosterol, with a catalytic efficiency 18-fold higher. The major CYP27A1-derived hydroxy-L2 products, 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2, inhibited the proliferation of melanoma and epidermoid cancer cell lines. In conclusion, this study shows that L2 is not metabolized appreciably by CYP11A1, but it is a good substrate for CYP27A1 which hydroxylates its side chain to produce 3 major products that display anti-proliferative activity on skin-cancer cell lines.
Topics: Humans; Ergosterol; Cholesterol Side-Chain Cleavage Enzyme; Hydroxylation; Mass Spectrometry; Ergocalciferols; Cholestanetriol 26-Monooxygenase
PubMed: 37499840
DOI: 10.1016/j.jsbmb.2023.106370 -
Foods (Basel, Switzerland) Aug 2023Alzheimer's disease (AD) stands as a prevailing neurodegenerative condition (NDs), leading to the gradual deterioration of brain cells and subsequent declines in memory,... (Review)
Review
Alzheimer's disease (AD) stands as a prevailing neurodegenerative condition (NDs), leading to the gradual deterioration of brain cells and subsequent declines in memory, thinking, behavior, and emotion. Despite the intensive research efforts and advances, an effective curative treatment for the disease has not yet been found. Mushrooms, esteemed globally for their exquisite flavors and abundant nutritional benefits, also hold a wealth of health-promoting compounds that contribute to improving AD health. These compounds encompass polysaccharides, proteins, lipids, terpenoids, phenols, and various other bioactive substances. Particularly noteworthy are the potent neuroprotective small molecules found in mushrooms, such as ergothioneine, erinacine, flavonoids, alkaloids, ergosterol, and melanin, which warrant dedicated scrutiny for their therapeutic potential in combating AD. This review summarizes such positive effects of mushroom bioactive compounds on AD, with a hope to contribute to the development of functional foods as an early dietary intervention for this neurodegenerative disease.
PubMed: 37569241
DOI: 10.3390/foods12152972 -
Medicine Oct 2023The coronavirus disease-2019 (COVID-19) pandemic has resulted in a surge in stress, anxiety, and depression worldwide. Ashwagandha, an ayurvedic adaptogen has been... (Randomized Controlled Trial)
Randomized Controlled Trial
A standardized Ashwagandha root extract alleviates stress, anxiety, and improves quality of life in healthy adults by modulating stress hormones: Results from a randomized, double-blind, placebo-controlled study.
BACKGROUND
The coronavirus disease-2019 (COVID-19) pandemic has resulted in a surge in stress, anxiety, and depression worldwide. Ashwagandha, an ayurvedic adaptogen has been traditionally used to manage stress, anxiety, and general well-being.
OBJECTIVE
We assessed the effect of Ashwagandha root extract (ARE-500 mg) standardized for 2.5% withanolides as per USP protocol with piperine (5 mg of 95% piperine) once daily for 60 days (12.5 mg withanolides/day) to alleviate stress and anxiety in healthy individuals with mild to moderate symptoms.
METHODS
A randomized, double-blind, placebo-controlled study was conducted for 60 days using ARE (n = 27) and placebo (n = 27) once daily at night at Narayana Institute of Cardiac Sciences, Bangalore, and Vijaya Super Specialty Hospital, Nellore, in India. The objectives of this study were to assess an improvement in perceived stress scale (PSS), generalized anxiety disorder (GAD-7), quality of life (QOL), cognitive scores in the Cambridge Neuropsychological Test Automated Battery (CANTAB), changes in salivary cortisol, urinary serotonin, dopamine, serum levels of nitric oxide (NO), glutathione (GSH) and malondialdehyde (MDA) from baseline to end of the study. Safety was evaluated by laboratory parameters, and by monitoring any incidence of adverse events.
RESULTS
54 individuals were randomized and 50 of them completed the study. The PSS, GAD-7, and QOL scores improved significantly in all the participants taking ARE compared to the placebo. The CANTAB analysis revealed a significant improvement in multitasking, concentration, and decision taking time in ARE compared to placebo. ARE was also associated with a greater reduction in the morning salivary cortisol and an increase in urinary serotonin compared to placebo. Serum levels of NO, GSH, and MDA were not significantly different. Biochemical and hematological parameters remained in the normal range in all participants and ARE was well tolerated during the study.
CONCLUSION
The results of the study suggest that ARE with 2.5% withanolides can effectively improve stress and anxiety by reducing cortisol and increasing serotonin in healthy individuals with mild to moderate symptoms.
Topics: Humans; Adult; Quality of Life; Hydrocortisone; Serotonin; Withanolides; COVID-19; India; Anxiety Disorders; Anxiety; Double-Blind Method
PubMed: 37832082
DOI: 10.1097/MD.0000000000035521