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1.
PLoS Pathog ; 18(6): e1010089, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35687592

RESUMEN

Whether to commit limited cellular resources toward growth and proliferation, or toward survival and stress responses, is an essential determination made by Target of Rapamycin Complex 1 (TORC1) for a eukaryotic cell in response to favorable or adverse conditions. Loss of TORC1 function is lethal. The TORC1 inhibitor rapamycin that targets the highly conserved Tor kinase domain kills fungal pathogens like Candida albicans, but is also severely toxic to human cells. The least conserved region of fungal and human Tor kinases are the N-terminal HEAT domains. We examined the role of the 8 most N-terminal HEAT repeats of C. albicans Tor1. We compared nutritional- and stress responses of cells that express a message for N-terminally truncated Tor1 from repressible tetO, with cells expressing wild type TOR1 from tetO or from the native promoter. Some but not all stress responses were significantly impaired by loss of Tor1 N-terminal HEAT repeats, including those to oxidative-, cell wall-, and heat stress; in contrast, plasma membrane stress and antifungal agents that disrupt plasma membrane function were tolerated by cells lacking this Tor1 region. Translation was inappropriately upregulated during oxidative stress in cells lacking N-terminal Tor1 HEAT repeats despite simultaneously elevated Gcn2 activity, while activation of the oxidative stress response MAP kinase Hog1 was weak. Conversely, these cells were unable to take advantage of favorable nutritional conditions by accelerating their growth. Consuming oxygen more slowly than cells containing wild type TOR1 alleles during growth in glucose, cells lacking N-terminal Tor1 HEAT repeats additionally were incapable of utilizing non-fermentable carbon sources. They were also hypersensitive to inhibitors of specific complexes within the respiratory electron transport chain, suggesting that inefficient ATP generation and a resulting dearth of nucleotide sugar building blocks for cell wall polysaccharides causes cell wall integrity defects in these mutants. Genome-wide expression analysis of cells lacking N-terminal HEAT repeats showed dysregulation of carbon metabolism, cell wall biosynthetic enzymes, translational machinery biosynthesis, oxidative stress responses, and hyphal- as well as white-opaque cell type-associated genes. Targeting fungal-specific Tor1 N-terminal HEAT repeats with small molecules might selectively abrogate fungal viability, especially when during infection multiple stresses are imposed by the host immune system.


Asunto(s)
Candida albicans , Proteínas Fúngicas , Candida albicans/metabolismo , Carbono/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulación Fúngica de la Expresión Génica , Humanos , Hifa , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo
3.
PLoS Pathog ; 16(9): e1008328, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32936835

RESUMEN

Candida albicans cells depend on the energy derived from amino acid catabolism to induce and sustain hyphal growth inside phagosomes of engulfing macrophages. The concomitant deamination of amino acids is thought to neutralize the acidic microenvironment of phagosomes, a presumed requisite for survival and initiation of hyphal growth. Here, in contrast to an existing model, we show that mitochondrial-localized NAD+-dependent glutamate dehydrogenase (GDH2) catalyzing the deamination of glutamate to α-ketoglutarate, and not the cytosolic urea amidolyase (DUR1,2), accounts for the observed alkalization of media when amino acids are the sole sources of carbon and nitrogen. C. albicans strains lacking GDH2 (gdh2-/-) are viable and do not extrude ammonia on amino acid-based media. Environmental alkalization does not occur under conditions of high glucose (2%), a finding attributable to glucose-repression of GDH2 expression and mitochondrial function. Consistently, inhibition of oxidative phosphorylation or mitochondrial translation by antimycin A or chloramphenicol, respectively, prevents alkalization. GDH2 expression and mitochondrial function are derepressed as glucose levels are lowered from 2% (~110 mM) to 0.2% (~11 mM), or when glycerol is used as primary carbon source. Using time-lapse microscopy, we document that gdh2-/- cells survive, filament and escape from primary murine macrophages at rates indistinguishable from wildtype. In intact hosts, such as in fly and murine models of systemic candidiasis, gdh2-/- mutants are as virulent as wildtype. Thus, although Gdh2 has a critical role in central nitrogen metabolism, Gdh2-catalyzed deamination of glutamate is surprisingly dispensable for escape from macrophages and virulence. Consistently, using the pH-sensitive dye (pHrodo), we observed no significant difference between wildtype and gdh2-/- mutants in phagosomal pH modulation. Following engulfment of fungal cells, the phagosomal compartment is rapidly acidified and hyphal growth initiates and sustained under consistently acidic conditions within phagosomes. Together, our results demonstrate that amino acid-dependent alkalization is not essential for hyphal growth, survival in macrophages and hosts. An accurate understanding of the microenvironment within macrophage phagosomes and the metabolic events underlying the survival of phagocytized C. albicans cells and their escape are critical to understanding the host-pathogen interactions that ultimately determine the pathogenic outcome.


Asunto(s)
Candida albicans/inmunología , Candidiasis/inmunología , Drosophila melanogaster/inmunología , Glutamato Deshidrogenasa/metabolismo , Macrófagos/inmunología , Aminoácidos/genética , Aminoácidos/metabolismo , Animales , Candida albicans/patogenicidad , Candidiasis/metabolismo , Candidiasis/microbiología , Drosophila melanogaster/metabolismo , Drosophila melanogaster/microbiología , Femenino , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glutamato Deshidrogenasa/genética , Interacciones Huésped-Patógeno , Concentración de Iones de Hidrógeno , Macrófagos/microbiología , Ratones , Ratones Endogámicos C57BL , Nitrógeno , Fagosomas/inmunología , Fagosomas/metabolismo , Fagosomas/microbiología , Virulencia
4.
Bioorg Med Chem ; 44: 116293, 2021 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-34243044

RESUMEN

Antifungal development has gained increasing attention due to its limited armamentarium and drug resistance. Drug repurposing holds great potential in antifungal discovery. In this study, we explored the antifungal activity of artemisinin and its derivatives, dihydroartemisinin, artesunate and artemether. We identified that artemisinins can inhibit the growth of Candida albicans, and can enhance the activity of three commonly used antifungals, amphotericin B, micafungin and fluconazole (FLC), on Candida albicans growth and filamentation. Artemisinins possess stronger antifungal effect with FLC than with other antifungals. Among artemisinins, artemether exhibits the most potent antifungal activity with FLC and can recover the susceptibility of FLC-resistant clinical isolates to FLC treatment. The combinatorial antifungal activity of artemether and FLC is broad-spectrum, as it can inhibit the growth of Candida auris, Candida tropicalis, Candida parapsilosis, Saccharomyces cerevisiae and Cryptococcus neoformans. Mechanistic investigation revealed that artemether might enhance azole efficacy through disrupting the function of Pdr5, leading to intracellular accumulation of FLC. This study identified artemether as a novel FLC potentiator, providing potential therapeutic insights against fungal infection and antifungal resistance.


Asunto(s)
Transportadoras de Casetes de Unión a ATP/antagonistas & inhibidores , Antifúngicos/farmacología , Artemisininas/farmacología , Fluconazol/farmacología , Candida/efectos de los fármacos , Candida/crecimiento & desarrollo , Cryptococcus neoformans/efectos de los fármacos , Cryptococcus neoformans/crecimiento & desarrollo , Relación Dosis-Respuesta a Droga , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/crecimiento & desarrollo , Relación Estructura-Actividad
5.
PLoS Pathog ; 14(7): e1007076, 2018 07.
Artículo en Inglés | MEDLINE | ID: mdl-30059535

RESUMEN

Phosphate is an essential macronutrient required for cell growth and division. Pho84 is the major high-affinity cell-surface phosphate importer of Saccharomyces cerevisiae and a crucial element in the phosphate homeostatic system of this model yeast. We found that loss of Candida albicans Pho84 attenuated virulence in Drosophila and murine oropharyngeal and disseminated models of invasive infection, and conferred hypersensitivity to neutrophil killing. Susceptibility of cells lacking Pho84 to neutrophil attack depended on reactive oxygen species (ROS): pho84-/- cells were no more susceptible than wild type C. albicans to neutrophils from a patient with chronic granulomatous disease, or to those whose oxidative burst was pharmacologically inhibited or neutralized. pho84-/- mutants hyperactivated oxidative stress signalling. They accumulated intracellular ROS in the absence of extrinsic oxidative stress, in high as well as low ambient phosphate conditions. ROS accumulation correlated with diminished levels of the unique superoxide dismutase Sod3 in pho84-/- cells, while SOD3 overexpression from a conditional promoter substantially restored these cells' oxidative stress resistance in vitro. Repression of SOD3 expression sharply increased their oxidative stress hypersensitivity. Neither of these oxidative stress management effects of manipulating SOD3 transcription was observed in PHO84 wild type cells. Sod3 levels were not the only factor driving oxidative stress effects on pho84-/- cells, though, because overexpressing SOD3 did not ameliorate these cells' hypersensitivity to neutrophil killing ex vivo, indicating Pho84 has further roles in oxidative stress resistance and virulence. Measurement of cellular metal concentrations demonstrated that diminished Sod3 expression was not due to decreased import of its metal cofactor manganese, as predicted from the function of S. cerevisiae Pho84 as a low-affinity manganese transporter. Instead of a role of Pho84 in metal transport, we found its role in TORC1 activation to impact oxidative stress management: overexpression of the TORC1-activating GTPase Gtr1 relieved the Sod3 deficit and ROS excess in pho84-/- null mutant cells, though it did not suppress their hypersensitivity to neutrophil killing or hyphal growth defect. Pharmacologic inhibition of Pho84 by small molecules including the FDA-approved drug foscarnet also induced ROS accumulation. Inhibiting Pho84 could hence support host defenses by sensitizing C. albicans to oxidative stress.


Asunto(s)
Candida albicans/patogenicidad , Candidiasis/metabolismo , Estrés Oxidativo/fisiología , Simportadores de Protón-Fosfato/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Animales , Transporte Biológico/fisiología , Drosophila , Proteínas Fúngicas/metabolismo , Humanos , Ratones , Fosfatos/metabolismo , Transducción de Señal/fisiología , Virulencia
6.
Hepatology ; 70(2): 532-546, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-30153342

RESUMEN

The interaction between RNA-binding proteins (RBPs) and RNA plays an important role in regulating cellular function. However, decoding genome-wide protein-RNA regulatory networks as well as how cancer-related mutations impair RNA regulatory activities in hepatocellular carcinoma (HCC) remains mostly undetermined. We explored the genetic alteration patterns of RBPs and found that deleterious mutations are likely to occur on the surface of RBPs. We then constructed protein-RNA interactome networks by integration of target binding screens and expression profiles. Network analysis highlights regulatory principles among interacting RBPs. In addition, somatic mutations selectively target functionally important genes (cancer genes, core fitness genes, or conserved genes) and perturb the RBP-gene regulatory networks in cancer. These regulatory patterns were further validated using independent data. A computational method (Mutational Effect on RNA Interactome Topology) and a web-based, user-friendly resource were further proposed to analyze the RBP-gene regulatory networks across cancer types. Pan-cancer analysis also suggests that cancer cells selectively target "vulnerability" genes to perturb protein-RNA interactome that is involved in cancer hallmark-related functions. Specifically, we experimentally validated four pairs of RBP-gene interactions perturbed by mutations in HCC, which play critical roles in cell proliferation. Based on the expression of perturbed RBP and target genes, we identified three subtypes of HCC with different survival rates. Conclusion: Our results provide a valuable resource for characterizing somatic mutation-perturbed protein-RNA regulatory networks in HCC, yielding valuable insights into the genotype-phenotype relationships underlying human cancer, and potential biomarkers for precision medicine.


Asunto(s)
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Mutación , Proteínas de Unión al ARN/genética , ARN/genética , Carcinoma Hepatocelular/mortalidad , Carcinoma Hepatocelular/patología , Proliferación Celular , Redes Reguladoras de Genes , Humanos , Neoplasias Hepáticas/mortalidad , Neoplasias Hepáticas/patología , Mapas de Interacción de Proteínas , Tasa de Supervivencia
7.
Proc Natl Acad Sci U S A ; 114(24): 6346-6351, 2017 06 13.
Artículo en Inglés | MEDLINE | ID: mdl-28566496

RESUMEN

The Target of Rapamycin (TOR) pathway regulates morphogenesis and responses to host cells in the fungal pathogen Candida albicans Eukaryotic Target of Rapamycin complex 1 (TORC1) induces growth and proliferation in response to nitrogen and carbon source availability. Our unbiased genetic approach seeking unknown components of TORC1 signaling in C. albicans revealed that the phosphate transporter Pho84 is required for normal TORC1 activity. We found that mutants in PHO84 are hypersensitive to rapamycin and in response to phosphate feeding, generate less phosphorylated ribosomal protein S6 (P-S6) than the WT. The small GTPase Gtr1, a component of the TORC1-activating EGO complex, links Pho84 to TORC1. Mutants in Gtr1 but not in another TORC1-activating GTPase, Rhb1, are defective in the P-S6 response to phosphate. Overexpression of Gtr1 and a constitutively active Gtr1Q67L mutant suppresses TORC1-related defects. In Saccharomyces cerevisiae pho84 mutants, constitutively active Gtr1 suppresses a TORC1 signaling defect but does not rescue rapamycin hypersensitivity. Hence, connections from phosphate homeostasis (PHO) to TORC1 may differ between C. albicans and S. cerevisiae The converse direction of signaling from TORC1 to the PHO regulon previously observed in S. cerevisiae was genetically shown in C. albicans using conditional TOR1 alleles. A small molecule inhibitor of Pho84, a Food and Drug Administration-approved drug, inhibits TORC1 signaling and potentiates the activity of the antifungals amphotericin B and micafungin. Anabolic TORC1-dependent processes require significant amounts of phosphate. Our study shows that phosphate availability is monitored and also controlled by TORC1 and that TORC1 can be indirectly targeted by inhibiting Pho84.


Asunto(s)
Candida albicans/metabolismo , Proteínas Fúngicas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Fosfatos/metabolismo , Simportadores de Protón-Fosfato/metabolismo , Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Candida albicans/genética , Proteínas Fúngicas/antagonistas & inhibidores , Proteínas Fúngicas/genética , Eliminación de Gen , Genes Fúngicos , Hifa/genética , Hifa/crecimiento & desarrollo , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Modelos Biológicos , Proteínas de Unión al GTP Monoméricas/genética , Proteínas de Unión al GTP Monoméricas/metabolismo , Mutación , Simportadores de Protón-Fosfato/antagonistas & inhibidores , Simportadores de Protón-Fosfato/genética , Regulón , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de Señal
8.
J Cell Biochem ; 119(1): 269-277, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-28543594

RESUMEN

Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by a progressive loss of dopaminergic neurons in the midbrain. Several pathogenetic factors have been involved in the onset and progression of PD, including inflammation, oxidative stress, unfolded protein accumulation, and apoptosis. Ample evidence indicates that miRNAs could regulate post-transcriptional gene expression and neuronal disease. In this study, we evaluated the effects and mechanism of miR-124-3p on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in PC12 cells and SH-SY5Y cells. qRT-PCR results showed that the level of miR-124-3p was downregulated in 6-OHDA-treated PC12 and SH-SY5Y cells, and overexpression of miR-124-3p significantly promoted the cell viability of 6-OHDA-treated PC12 and SH-SY5Y cells, whereas miR-124-3p inhibitor reversed these effects. In addition, PC12 or SH-SY5Y cells were treated with miR-124-3p mimics or inhibitors following 6-OHDA administration, which mediated cell apoptosis and downregulation or upregulation of Caspase-3 activity, respectively. A luciferase reporter assay revealed that annexinA5 (ANXA5) is a direct target gene of miR-124-3p, and miR-124-3p overexpression markedly downregulated the level of ANXA5. Strikingly, further analysis showed that miR-124-3p enhanced the viability of 6-OHDA-treated PC12 or SH-SY5Y cells by targeting ANXA5, which was associated with the stimulation of the ERK pathway. This study revealed that miR-124-3p may play a neuroprotective role in PD; this observation may provide new ideas and therapeutic targets for PD. J. Cell. Biochem. 119: 269-277, 2018. © 2017 Wiley Periodicals, Inc.


Asunto(s)
Anexina A5/biosíntesis , Regulación de la Expresión Génica/efectos de los fármacos , MicroARNs/biosíntesis , Modelos Biológicos , Neuroprotección , Oxidopamina/efectos adversos , Enfermedad de Parkinson Secundaria/metabolismo , Animales , Anexina A5/genética , MicroARNs/genética , Oxidopamina/farmacología , Células PC12 , Enfermedad de Parkinson Secundaria/inducido químicamente , Enfermedad de Parkinson Secundaria/genética , Enfermedad de Parkinson Secundaria/patología , Ratas
9.
Breast Cancer Res ; 20(1): 77, 2018 07 25.
Artículo en Inglés | MEDLINE | ID: mdl-30045762

RESUMEN

The authors are retracting this article [1] after an investigation by the Ethics Committee of the Fourth Military Medical University (Xi'an, Shaanxi, China) of the following concerns that had been raised with respect to two of the figures.

10.
Cell Physiol Biochem ; 44(4): 1640-1650, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29216640

RESUMEN

BACKGROUND/AIMS: The goal of this study was to detect the expression of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) in human retinal pigmented epithelial (RPE) cells treated with celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, under hypoxic and normoxic conditions and to explore the signaling mechanism involved in regulating the hypoxia-induced expression of HIF-1α and VEGF in RPE cells. METHODS: D407 cells were cultured in normoxic or hypoxic conditions, with or without celecoxib or a PI3K inhibitor (LY294002). The anti-proliferative effect of celecoxib was assessed using the MTT assay. RT-PCR, Western blotting and ELISA were performed to detect the levels of PI3K, phosphorylated AKT (p-AKT), HIF-1α, VEGF and COX-2. RESULTS: Celecoxib inhibited the proliferation of RPE cells in a dose-dependent manner. Celecoxib suppressed the expression of VEGF at both the mRNA and protein levels and decreased HIF-1α protein expression. HIF-1α activation was regulated by the PI3K/AKT pathway. The celecoxib-induced down-regulation of HIF-1α and VEGF required the suppression of the hypoxia-induced PI3K/AKT pathway. However, the down-regulation of COX-2 did not occur in cells treated with celecoxib. CONCLUSIONS: The antiangiogenic effects of celecoxib in RPE cells under hypoxic conditions resulted from the inhibition of HIF-1α and VEGF expression, which may be partly mediated by a COX-2-independent, PI3K/AKT-dependent pathway.


Asunto(s)
Celecoxib/farmacología , Hipoxia de la Célula , Inhibidores de la Ciclooxigenasa 2/farmacología , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Transducción de Señal/efectos de los fármacos , Factor A de Crecimiento Endotelial Vascular/metabolismo , Línea Celular , Proliferación Celular/efectos de los fármacos , Cromonas/farmacología , Ciclooxigenasa 2/química , Ciclooxigenasa 2/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Morfolinas/farmacología , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilación , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/metabolismo , Factor A de Crecimiento Endotelial Vascular/genética
11.
Antimicrob Agents Chemother ; 60(2): 1145-7, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26596946

RESUMEN

Hospitalized ill patients, at risk for invasive candidiasis, often receive multiple medications, including proton pump inhibitors (PPIs). The antifungal fluconazole perturbs the vacuolar proton ATPase. The PPI omeprazole antagonized Candida albicans growth inhibition by fluconazole. A C. albicans codon-adapted pHluorin, Ca.pHluorin, was generated to measure cytosolic pH. The fungal cytosol was acidified by omeprazole and realkalinized by coexposure to fluconazole. Vacuolar pH was alkalinized by fluconazole. Off-target effects of any medication on fungal pathogens may occur.


Asunto(s)
Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Fluconazol/antagonistas & inhibidores , Omeprazol/farmacología , Inhibidores de la Bomba de Protones/farmacología , Candida albicans/genética , Citosol/efectos de los fármacos , Antagonismo de Drogas , Fluconazol/farmacología , Concentración de Iones de Hidrógeno
12.
Biochem Biophys Res Commun ; 475(4): 329-34, 2016 07 08.
Artículo en Inglés | MEDLINE | ID: mdl-27216460

RESUMEN

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and GATA Binding Protein 4 (GATA4) are important for the growth of cardiac fibroblasts (CFs). When deregulated, LOX-1 and GATA4 can cause cardiac remodeling. In the present study, we found novel evidence that GATA4 was required for the LOX-1 regulation of CF proliferation. The inhibition of LOX-1 by RNA interference LOX-1 lentivirus resulted in the loss of PI3K/Akt activation and GATA4 protein expression. The overexpression of LOX-1 by lentivirus rescued CF proliferation, PI3K/Akt activation, and GATA4 protein expression. Moreover, GATA4 overexpression enhanced CF proliferation with LOX-1 inhibition. We also found that the inhibition of PI3K/Akt activation by LY294002, a PI3K inhibitor, reduced cell proliferation and protein level of GATA4. In summary, GATA4 may play an important role in the LOX-1 and PI3K/Akt regulation of CF proliferation.


Asunto(s)
Proliferación Celular , Fibroblastos/citología , Factor de Transcripción GATA4/metabolismo , Miocardio/citología , Receptores Depuradores de Clase E/metabolismo , Animales , Células Cultivadas , Fibroblastos/metabolismo , Miocardio/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas Sprague-Dawley , Transducción de Señal
13.
PLoS Genet ; 9(1): e1003208, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23390378

RESUMEN

Telomeres are protein-DNA structures found at the ends of linear chromosomes and are crucial for genome integrity. Telomeric DNA length is primarily maintained by the enzyme telomerase. Cells lacking telomerase will undergo senescence when telomeres become critically short. In Saccharomyces cerevisiae, a very small percentage of cells lacking telomerase can remain viable by lengthening telomeres via two distinct homologous recombination pathways. These "survivor" cells are classified as either Type I or Type II, with each class of survivor possessing distinct telomeric DNA structures and genetic requirements. To elucidate the regulatory pathways contributing to survivor generation, we knocked out the telomerase RNA gene TLC1 in 280 telomere-length-maintenance (TLM) gene mutants and examined telomere structures in post-senescent survivors. We uncovered new functional roles for 10 genes that affect the emerging ratio of Type I versus Type II survivors and 22 genes that are required for Type II survivor generation. We further verified that Pif1 helicase was required for Type I recombination and that the INO80 chromatin remodeling complex greatly affected the emerging frequency of Type I survivors. Finally, we found the Rad6-mediated ubiquitination pathway and the KEOPS complex were required for Type II recombination. Our data provide an independent line of evidence supporting the idea that these genes play important roles in telomere dynamics.


Asunto(s)
ADN Helicasas , Recombinación Homóloga , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Telomerasa/genética , Cromosomas/genética , ADN Helicasas/genética , ADN Helicasas/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Inestabilidad Genómica , ARN/genética , ARN/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Telomerasa/metabolismo , Telómero/genética , Homeostasis del Telómero/genética , Ubiquitinación
14.
Cell Physiol Biochem ; 37(3): 991-1001, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26393789

RESUMEN

BACKGROUND/AIMS: To investigate the roles of hypoxia-inducible factor 1α (HIF-1α), cyclooxygenase-2 (Cox-2) and its product, Prostaglandin E2 (PGE2), in the mechanisms underlying hypoxia-induced survivin expression in human umbilical vein endothelial cells (HUVECs) and to examine the effect of celecoxib, a selective Cox-2 inhibitor, on survivin expression. METHODS: HUVECs were exposed to a normal (95% O2) or hypoxic (3% O2) environment for 24 hrs. We observed the localized expression of survivin, Cox-2 and HIF-1α in HUVECs using immunocytochemistry and detected the inhibitory effects of celecoxib on the growth of HUVECs using an MTT assay. mRNA and protein levels of Cox-2, HIF-1α and survivin were determined by real-time PCR and Western blot analysis under hypoxic conditions for 0, 6, 12, or 24 hrs. The time course changes of HIF-1α and survivin protein expression induced by cobalt chloride (CoCl2) were studied using Western blot analysis. We then treated HUVECs under hypoxia for 24 hrs with celecoxib (a Cox-2 selective inhibitor), genistein (a HIF-1α inhibitor) or exogenous PGE2 to further investigate the changes in hypoxia-induced survivin expression. RESULTS: Following 24 hrs of hypoxic treatment, cells exhibited strongly positive survivin, HIF-1α and Cox-2 cytoplasmic staining. Celecoxib (65 µM) effectively inhibited cell proliferation under hypoxic conditions. The protein and mRNA levels of Cox-2, HIF-1α and survivin were increased under hypoxia. The patterns of HIF-1α and survivin expression induced by CoCl2 were similar to those induced by exposure to hypoxia. Genistein partially blocked survivin expression. Celecoxib reversed the hypoxia-induced survivin expression, whereas the addition of PGE2 partially restored this effect. CONCLUSIONS: Hypoxia-induced survivin expression in HUVECs may be mediated by dual interdependent mechanisms directly involving HIF-1α and indirectly involving the Cox-2/PGE2 pathways. Celecoxib may offset hypoxia-induced survivin expression.


Asunto(s)
Celecoxib/farmacología , Inhibidores de la Ciclooxigenasa 2/farmacología , Proteínas Inhibidoras de la Apoptosis/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Hipoxia de la Célula , Proliferación Celular/efectos de los fármacos , Cobalto/farmacología , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Dinoprostona/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Genisteína/farmacología , Células Endoteliales de la Vena Umbilical Humana , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Proteínas Inhibidoras de la Apoptosis/genética , Survivin
15.
IUBMB Life ; 67(6): 446-52, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25988388

RESUMEN

Rapamycin, a highly specific inhibitor of mammalian target of rapamycin (mTOR), exhibits significant antitumor/antiangiogenic activity in human cancer cells. Its effect on the retinal pigment epithelial (RPE) cells was rarely investigated. This study assessed the proliferation of hypoxia-induced RPE and the inhibitory effects of rapamycin using 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and examined the expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in RPE cells with or without rapamycin under normoxic and hypoxic conditions using real-time PCR and Western blot. We found that hypoxia increased the levels of mTOR, HIF-1α, and VEGF. The suppression of HIF-1α and VEGF by rapamycin was associated with dephosphorylation of mTOR and the downstream effector ribosomal protein S6 kinase (P70S6K) and 4E-binding protein-1 (4E-BP1) of mTORC1. Rapamycin only inhibited the protein levels and did not change the mRNA expression of HIF-1α. No cytotoxicity to the RPE cells by rapamycin was caused under either normoxia or hypoxia. Our data suggest that rapamycin suppresses hypoxia-induced RPE cell proliferation through a mechanism related to the targeting of mTOR/HIF-1α/VEGF signaling. Rapamycin may potentially provide a safe and effective novel treatment for choroidal vascular disease.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Epitelio Pigmentado de la Retina/citología , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas de Ciclo Celular , Hipoxia de la Célula/efectos de los fármacos , Línea Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Ensayo de Inmunoadsorción Enzimática/métodos , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Fosfoproteínas/metabolismo , Epitelio Pigmentado de la Retina/efectos de los fármacos , Epitelio Pigmentado de la Retina/metabolismo , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/genética , Factor A de Crecimiento Endotelial Vascular/genética
16.
Clin Exp Ophthalmol ; 43(5): 458-65, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25472856

RESUMEN

BACKGROUND: To explore the anti-angiogenesis mechanism of Rofecoxib and determine whether Rofecoxib can be a therapeutic agent for the prevention of retinal neovascularization using a model of retinopathy of prematurity (ROP). METHODS: ROP was induced by exposing mice to 75% oxygen from postnatal day 7 (P7 ) to P12 , then to room air from P12 to P17 . Sixteen mice were in each of the three groups: untreated ROP group as positive control, Rofecoxib-treated ROP group and the normal group (age-matched mice maintained in room air from birth to P17 as negative control). The localized expression of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) protein and mRNA in retinal blood vessels was assessed using immunohistochemistry, Western blot analysis and reverse transcription polymerase chain reaction. RESULTS: Mice in the Rofecoxib-treated group had a significantly reduced retinal neovascular tufts compared with those in the untreated ROP group. COX-2 and VEGF protein and mRNA expression levels were increased in the untreated ROP group, compared with the normal group. Rofecoxib decreased retinal angiogenesis by inhibiting COX-2 and VEGF expression. The expression levels of VEGF and COX-2 were positively correlated at mRNA and protein levels. CONCLUSIONS: COX-2 and VEGF expressions were both involved in the regulation of angiogenesis and had the same cellular localization. Expression of COX-2 correlated positively with VEGF in retinal neovascularization. Rofecoxib attenuated retinal angiogenesis by inhibiting the expression of COX-2 and VEGF mRNA and protein.


Asunto(s)
Inhibidores de la Ciclooxigenasa 2/uso terapéutico , Ciclooxigenasa 2/genética , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/efectos de los fármacos , Lactonas/uso terapéutico , Neovascularización Retiniana/prevención & control , Sulfonas/uso terapéutico , Factor A de Crecimiento Endotelial Vascular/genética , Animales , Animales Recién Nacidos , Western Blotting , Ciclooxigenasa 2/metabolismo , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , ARN Mensajero/genética , Neovascularización Retiniana/genética , Neovascularización Retiniana/metabolismo , Vasos Retinianos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor A de Crecimiento Endotelial Vascular/metabolismo
17.
Breast Cancer Res ; 16(5): 454, 2014 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-25311085

RESUMEN

INTRODUCTION: The onset of distal metastasis, which underlies the high mortality of breast cancers, warrants substantial studies to depict its molecular basis. Nuclear factor of activated T cells 5 (NFAT5) is upregulated in various malignancies and is critically involved in migration and invasion of neoplastic cells. Nevertheless, the metastasis-related events potentiated by this transcriptional factor and the mechanism responsible for NFAT5 elevation in carcinoma cells remain to be fully elucidated. METHODS: The correlation of NFAT5 with breast cancer invasiveness was investigated in vitro and clinically. The genes transcriptionally activated by NFAT5 were probed and their roles in breast cancer progression were dissected. The upstream regulators of NFAT5 were studied with particular attempt to explore the involvement of non-coding RNAs, and the mechanism underlying the maintenance of NFAT5 expression was deciphered. RESULTS: In metastatic breast cancers, NFAT5 promotes epithelial-mesenchymal transition (EMT) and invasion of cells by switching on the expression of the calcium binding protein S100A4, and facilitates the angiogenesis of breast epithelial cells and thus the development of metastases by transcriptionally activating vascular endothelial growth factor C (VEGF-C). NFAT5 is directly targeted by miR-568, which is in turn suppressed by the long non-coding RNA, Hotair, via a documented in trans gene silencing pattern, that is recruitment of the polycomb complex (Polycomb Repressive Complex 2; PRC2) and LSD1, and consequently methylation of histone H3K27 and demethylation of H3K4 on the miR-568 loci. CONCLUSION: This study unravels a detailed role of NFAT5 in mediating metastatic signaling, and provides broad insights into the involvement of Hotair, in particular, by transcriptionally regulating the expression of microRNA(s), in the metastasis of breast cancers.


Asunto(s)
Neoplasias de la Mama/metabolismo , Neoplasias Pulmonares/metabolismo , MicroARNs/genética , ARN Largo no Codificante/genética , Proteínas S100/metabolismo , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , Sitios de Unión , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Línea Celular Tumoral , Transición Epitelial-Mesenquimal , Femenino , Regulación Neoplásica de la Expresión Génica , Células Endoteliales de la Vena Umbilical Humana/fisiología , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/secundario , Metástasis Linfática , Ratones Endogámicos BALB C , Ratones Desnudos , Trasplante de Neoplasias , Interferencia de ARN , Proteína de Unión al Calcio S100A4 , Proteínas S100/genética , Factores de Transcripción/genética , Regulación hacia Arriba , Factor C de Crecimiento Endotelial Vascular/genética , Factor C de Crecimiento Endotelial Vascular/metabolismo
18.
Trends Cancer ; 10(5): 389-392, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38494372

RESUMEN

The cancer mycobiome has recently become a research hotspot. While the intratumor mycobiota is implicated in cancer initiation and progression, the gut mycobiota functions as biomarkers for cancer diagnosis and treatment. In this forum article we highlight the involvement of the mycobiome in correlation-, causation-, and prediction-oriented cancer research and discuss the potential of this burgeoning field.


Asunto(s)
Microbioma Gastrointestinal , Micobioma , Neoplasias , Humanos , Neoplasias/microbiología , Biomarcadores de Tumor/metabolismo , Investigación Biomédica
19.
mLife ; 3(2): 219-230, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38948147

RESUMEN

Human microbiomes, considered as a new emerging and enabling cancer hallmark, are increasingly recognized as critical effectors in cancer development and progression. Manipulation of microbiome revitalizing anticancer therapy from natural products shows promise toward improving cancer outcomes. Herein, we summarize our current understanding of the human microbiome-driven molecular mechanisms impacting cancer progression and anticancer therapy. We highlight the potential translational and clinical implications of natural products for cancer prevention and treatment by developing targeted therapeutic strategies as adjuvants for chemotherapy and immunotherapy against tumorigenesis. The challenges and opportunities for future investigations using modulation of the microbiome for cancer treatment are further discussed in this review.

20.
Imeta ; 3(2): e170, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38882486

RESUMEN

The human microbiome exhibits a profound connection with the cancer development, progression, and therapeutic response, with particular emphasis on its components of the mycobiome, which are still in the early stages of research. In this review, we comprehensively summarize cancer-related symbiotic and pathogenic fungal genera. The intricate mechanisms through which fungi impact cancer as an integral member of both gut and tissue-resident microbiomes are further discussed. In addition, we shed light on the pivotal physiological roles of various nutrients, including cholesterol, carbohydrates, proteins and minerals, in facilitating the growth, reproduction, and invasive pathogenesis of the fungi. While our exploration of the interplay between nutrients and cancer, mediated by the mycobiome, is ongoing, the current findings have yet to yield conclusive results. Thus, delving into the relationship between nutrients and fungal pathogenesis in cancer development and progression would provide valuable insights into anticancer therapy and foster precision nutrition and individualized treatments that target fungi from bench to bedside.

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