scholarly journals Monitoring Glycolysis and Respiration Highlights Metabolic Inflexibility of Cryptococcus neoformans

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 684
Author(s):  
Sophie Lev ◽  
Cecilia Li ◽  
Desmarini Desmarini ◽  
David Liuwantara ◽  
Tania C. Sorrell ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Metabolic Flux ◽  
Extracellular Acidification ◽  
Human Fungal Pathogen ◽  
Tightly Coupled ◽  
Obligate Aerobe ◽  
Type C ◽  
Metabolic Inflexibility ◽  
Insight Into ◽  
Limited Oxygen

Cryptococcus neoformans is a human fungal pathogen that adapts its metabolism to cope with limited oxygen availability, nutrient deprivation and host phagocytes. To gain insight into cryptococcal metabolism, we optimized a protocol for the Seahorse Analyzer, which measures extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indications of glycolytic and respiratory activities. In doing so we achieved effective immobilization of encapsulated cryptococci, established Rotenone/Antimycin A and 2-deoxyglucose as effective inhibitors of mitochondrial respiration and glycolysis, respectively, and optimized a microscopy-based method of data normalization. We applied the protocol to monitor metabolic changes in the pathogen alone and in co-culture with human blood-derived monocytes. We also compared metabolic flux in wild-type C. neoformans, its isogenic 5-PP-IP5/IP7-deficient metabolic mutant kcs1∆, the sister species of C. neoformans, Cryptococcus deuterogattii/VGII, and two other yeasts, Saccharomyces cerevisiae and Candida albicans. Our findings show that in contrast to monocytes and C. albicans, glycolysis and respiration are tightly coupled in C. neoformans and C. deuterogattii, as no compensatory increase in glycolysis occurred following inhibition of respiration. We also demonstrate that kcs1∆ has reduced metabolic activity that correlates with reduced mitochondrial function. Metabolic inflexibility in C. neoformans is therefore consistent with its obligate aerobe status and coincides with phagocyte tolerance of ingested cryptococcal cells.

scholarly journals Titan Cells Confer Protection from Phagocytosis in Cryptococcus neoformans Infections

2012 ◽  
Vol 11 (6) ◽  
pp. 820-826 ◽  
Author(s):  
Laura H. Okagaki ◽  
Kirsten Nielsen
Keyword(s):  
Cryptococcus Neoformans ◽  
Critical Role ◽  
Cell Formation ◽  
Pulmonary Cryptococcosis ◽  
Content Type ◽  
Cell Production ◽  
Human Fungal Pathogen ◽  
Large Size ◽  
Large Particles ◽  
The Relationship

ABSTRACTThe human fungal pathogenCryptococcus neoformansproduces an enlarged “titan” cell morphology when exposed to the host pulmonary environment. Titan cells exhibit traits that promote survival in the host. Previous studies showed that titan cells are not phagocytosed and that increased titan cell production in the lungs results in reduced phagocytosis of cryptococcal cells by host immune cells. Here, the effect of titan cell production on host-pathogen interactions during early stages of pulmonary cryptococcosis was explored. The relationship between titan cell production and phagocytosis was found to be nonlinear; moderate increases in titan cell production resulted in profound decreases in phagocytosis, with significant differences occurring within the first 24 h of the infection. Not only were titan cells themselves protected from phagocytosis, but titan cell formation also conferred protection from phagocytosis to normal-size cryptococcal cells. Large particles introduced into the lungs were not phagocytosed, suggesting the large size of titan cells protects against phagocytosis. The presence of large particles was unable to protect smaller particles from phagocytosis, revealing that titan cell size alone is not sufficient to provide the observed cross-protection of normal-size cryptococcal cells. These data suggest that titan cells play a critical role in establishment of the pulmonary infection by promoting the survival of the entire population of cryptococcal cells.

scholarly journals Pleiotropic Roles of the Msi1-Like Protein Msl1 in Cryptococcus neoformans

2012 ◽  
Vol 11 (12) ◽  
pp. 1482-1495 ◽  
Author(s):  
Dong-Hoon Yang ◽  
Shinae Maeng ◽  
Anna K. Strain ◽  
Anna Floyd ◽  
Kirsten Nielsen ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Stress Responses ◽  
Fungal Pathogens ◽  
Independent Manner ◽  
Content Type ◽  
Antifungal Drug Resistance ◽  
Human Fungal Pathogen ◽  
Assembly Factor ◽  
Life Threatening ◽  
Stress Related Genes

ABSTRACT Msi1-like (MSIL) proteins contain WD40 motifs and have a pleiotropic cellular function as negative regulators of the Ras/cyclic AMP (cAMP) pathway and components of chromatin assembly factor 1 (CAF-1), yet they have not been studied in fungal pathogens. Here we identified and characterized an MSIL protein, Msl1, in Cryptococcus neoformans , which causes life-threatening meningoencephalitis in humans. Notably, Msl1 plays pleiotropic roles in C. neoformans in both cAMP-dependent and -independent manners largely independent of Ras. Msl1 negatively controls antioxidant melanin production and sexual differentiation, and this was repressed by the inhibition of the cAMP-signaling pathway. In contrast, Msl1 controls thermotolerance, diverse stress responses, and antifungal drug resistance in a Ras/cAMP-independent manner. Cac2, which is the second CAF-1 component, appears to play both redundant and distinct functions compared to the functions of Msl1. Msl1 is required for the full virulence of C. neoformans . Transcriptome analysis identified a group of Msl1-regulated genes, which include stress-related genes such as HSP12 and HSP78 . In conclusion, this study demonstrates pleiotropic roles of Msl1 in the human fungal pathogen C. neoformans , providing insight into a potential novel antifungal therapeutic target.

Broadening the spectrum of fluorescent protein tools for use in the encapsulated human fungal pathogen Cryptococcus neoformans

2020 ◽  
Vol 138 ◽  
pp. 103365
Author(s):  
Garrick W.K. Spencer ◽  
Sheena M.H. Chua ◽  
Paige E. Erpf ◽  
Maha S.I. Wizrah ◽  
Taylor G. Dyba ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Fluorescent Protein ◽  
Human Fungal Pathogen

scholarly journals Structural analysis of fungal pathogenicity-related casein kinase α subunit, Cka1, in the human fungal pathogen Cryptococcus neoformans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Belinda X. Ong ◽  
Youngki Yoo ◽  
Myeong Gil Han ◽  
Jun Bae Park ◽  
Myung Kyung Choi ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Pathogenic Fungus ◽  
Kinase Assay ◽  
Α Subunit ◽  
Dynamic Architecture ◽  
Human Fungal Pathogen ◽  
Life Threatening ◽  
The Difference ◽  
Anti Fungal

Abstract CK2α is a constitutively active and highly conserved serine/threonine protein kinase that is involved in the regulation of key cellular metabolic pathways and associated with a variety of tumours and cancers. The most well-known CK2α inhibitor is the human clinical trial candidate CX-4945, which has recently shown to exhibit not only anti-cancer, but also anti-fungal properties. This prompted us to work on the CK2α orthologue, Cka1, from the pathogenic fungus Cryptococcus neoformans, which causes life-threatening systemic cryptococcosis and meningoencephalitis mainly in immunocompromised individuals. At present, treatment of cryptococcosis remains a challenge due to limited anti-cryptococcal therapeutic strategies. Hence, expanding therapeutic options for the treatment of the disease is highly clinically relevant. Herein, we report the structures of Cka1-AMPPNP-Mg2+ (2.40 Å) and Cka1-CX-4945 (2.09 Å). Structural comparisons of Cka1-AMPPNP-Mg2+ with other orthologues revealed the dynamic architecture of the N-lobe across species. This may explain for the difference in binding affinities and deviations in protein-inhibitor interactions between Cka1-CX-4945 and human CK2α-CX-4945. Supporting it, in vitro kinase assay demonstrated that CX-4945 inhibited human CK2α much more efficiently than Cka1. Our results provide structural insights into the design of more selective inhibitors against Cka1.

High level of C-type natriuretic peptide induced by hyperandrogen-mediated anovulation in polycystic ovary syndrome mice

2018 ◽  
Vol 132 (7) ◽  
pp. 759-776 ◽  
Author(s):  
Xiao Wang ◽  
Huarong Wang ◽  
Wei Liu ◽  
Zhiyuan Zhang ◽  
Yanhao Zhang ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Natriuretic Peptide ◽  
Polycystic Ovary ◽  
Germinal Vesicle ◽  
Ovary Syndrome ◽  
Oocyte Meiosis ◽  
Type C ◽  
High Level ◽  
Reproductive Aged Women ◽  
Insight Into

Polycystic ovary syndrome (PCOS), which is characterized by hyperandrogenism, is a complex endocrinopathy that affects the fertility of 9–18% of reproductive-aged women. However, the exact mechanism of PCOS, especially hyperandrogen-induced anovulation, is largely unknown to date. Physiologically, the natriuretic peptide type C/natriuretic peptide receptor 2 (CNP/NPR2) system is essential for sustaining oocyte meiotic arrest until the preovulatory luteinizing hormone (LH) surge. We therefore hypothesized that the CNP/NPR2 system is also involved in PCOS and contributes to arresting oocyte meiosis and ovulation. Here, based on a dehydroepiandrosterone (DHEA)-induced PCOS-like mouse model, persistent high levels of CNP/NPR2 were detected in anovulation ovaries. Meanwhile, oocytes arrested at the germinal vesicle stage correlated with persistent high levels of androgen and estrogen. We further showed that ovulation failure in these mice could be a result of elevated Nppc/Npr2 gene transcription that was directly increased by androgen (AR) and estrogen (ER) receptor signaling. Consistent with this, anovulation was alleviated by administration of either exogenous human chorionic gonadotropin (hCG) or inhibitors of AR or ER to reduce the level of CNP/NPR2. Additionally, the CNP/NPR2 expression pattern in the anovulated follicles was, to some extent, consistent with the clinical expression in PCOS patients. Therefore, our study highlights the important role an overactive CNP/NPR2 system caused by hyperandrogenism in preventing oocytes from maturation and ovulation in PCOS mice. Our findings provide insight into potential mechanisms responsible for infertility in women with PCOS.

scholarly journals Metabolic flexibility during sleep

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simeng Zhang ◽  
Yoshiaki Tanaka ◽  
Asuka Ishihara ◽  
Akiko Uchizawa ◽  
Insung Park ◽  
...  
Keyword(s):  
Young Adults ◽  
Time Resolution ◽  
Diurnal Rhythm ◽  
Indirect Calorimetry ◽  
Early Stage ◽  
Metabolic Flexibility ◽  
Extended Duration ◽  
Older Subjects ◽  
Metabolic Inflexibility ◽  
Insight Into

AbstractKnown as metabolic flexibility, oxidized substrate is selected in response to changes in the nutritional state. Sleep imposes an extended duration of fasting, and oxidized substrates during sleep were assumed to progressively shift from carbohydrate to fat, thereby gradually decreasing the respiratory quotient (RQ). Contrary to this assumption, whole-room indirect calorimetry with improved time resolution revealed that RQ re-ascended prior to awakening, and nadir of RQ in non-obese young adults occurred earlier in women than men after bedtime. The transient decrease in RQ during sleep was blunted in metabolically inflexible men with smaller amplitude of diurnal rhythm in RQ. Similarly, the effect of 10 years difference in age on RQ became significant during sleep; the decrease in RQ during sleep was blunted in older subjects. Inter-individual difference in RQ become apparent during sleep, and it might serve as a window to gain insight into the early-stage pathogenesis of metabolic inflexibility.

scholarly journals Erg6 affects membrane composition and virulence of the human fungal pathogen Cryptococcus neoformans

2020 ◽  
Vol 140 ◽  
pp. 103368 ◽  
Author(s):  
Fabiana Freire M. Oliveira ◽  
Hugo Costa Paes ◽  
Luísa Defranco F. Peconick ◽  
Fernanda L. Fonseca ◽  
Clara Luna Freitas Marina ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Membrane Composition ◽  
Human Fungal Pathogen
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