Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
1.
J Integr Neurosci ; 23(5): 107, 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38812388

RESUMO

BACKGROUND: Methamphetamine (METH) is a highly addictive drug that directly affects the central nervous system. METH use not only harms the user's health but also poses risks and costs to society. Prolonged METH dependence has been shown to impair cognition, which may be the primary factor in impulsive drug-seeking behaviors and high relapse rates. However, the molecular mechanisms underlying METH addiction and METH-induced cognitive decline remain poorly understood. METHODS: To illuminate the potential molecular mechanisms underpinning METH addiction, we compared serum protein expression levels between 12 long-term METH users and 12 healthy controls using label-free quantitative proteomics. Bioinformatic analyses were conducted to determine functional networks and protein-protein interactions. RESULTS: In total, 23 differentially expressed proteins were identified between the two groups. The differentially expressed proteins were related to cognitive dysfunction, neuroinflammation, immune impairment, metabolic disturbances, and calcium binding and regulation. CONCLUSIONS: These 23 proteins may underpin the multi-system damage induced by chronic METH exposure. Our findings provide novel insights into the molecular basis of METH addiction and inform potential prevention and treatment strategies for individuals with METH dependence.


Assuntos
Transtornos Relacionados ao Uso de Anfetaminas , Estimulantes do Sistema Nervoso Central , Disfunção Cognitiva , Metanfetamina , Proteômica , Humanos , Transtornos Relacionados ao Uso de Anfetaminas/metabolismo , Masculino , Metanfetamina/efeitos adversos , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/induzido quimicamente , Disfunção Cognitiva/etiologia , Adulto , Estimulantes do Sistema Nervoso Central/efeitos adversos , Estimulantes do Sistema Nervoso Central/farmacologia , Feminino , Adulto Jovem
2.
Zootaxa ; 5415(3): 392-400, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38480195

RESUMO

A new genus of the spider family Trachelidae L. Koch, 1872, Cornifronus gen. nov. from China is described, as well as one new species, C. simplex sp. nov. (), known only from Hainan and Yunnan Province.


Assuntos
Aranhas , Animais , China
3.
Rice (N Y) ; 16(1): 52, 2023 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-38006430

RESUMO

Early spring cold spells can lead to leaf chlorosis during the rice seedling greening process. However, the physiological and molecular mechanisms underlying the rice greening process under low-temperature conditions remain unknown. In this study, comparative transcriptome and morphophysiological analyses were performed to investigate the mechanisms mediating the responses of the Koshihikari (Kos) and Kasalath (Kas) rice cultivars to chilling stress. According to their growth-related traits, electrolyte leakage, and chlorophyll fluorescence parameters, Kos was more tolerant to low-temperature stress than Kas. Moreover, chloroplast morphology was more normal (e.g., oval) in Kos than in Kas at 17 °C. The comparative transcriptome analysis revealed 610 up-regulated differentially expressed genes that were common to all four comparisons. Furthermore, carotenoid biosynthesis was identified as a critical pathway for the Kos response to chilling stress. The genes in the carotenoid biosynthesis pathway were expressed at higher levels in Kos than in Kas at 17 °C, which was in accordance with the higher leaf carotenoid content in Kos than in Kas. The lycopene ß-cyclase and lycopene ε-cyclase activities increased more in Kos than in Kas. Additionally, the increases in the violaxanthin de-epoxidase and carotenoid hydroxylase activities in Kos seedlings resulted in the accumulation of zeaxanthin and lutein and mitigated the effects of chilling stress on chloroplasts. These findings have clarified the molecular mechanisms underlying the chilling tolerance of rice seedlings during the greening process.

4.
J Control Release ; 363: 597-605, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37793484

RESUMO

Tremendous efforts have been made to improve polymeric property in gene delivery performances, especially when obstacle of transferring gene construct into difficult-to-transfect cells occurs. Innovations in the area of fluorination and fluorinated compounds with biomedical potential in medicinal chemistry are believed to assist in the development of new therapeutics. Fluorine modified polymers have shown to navigate the gene transfection cellular barriers and promoted the transfection outcomes. Gene transfer into some liver cancer cells and human leukemia cells has always been a challenge. Here, by facile incorporation of a fluorine containing amine monomer, 1H,1H-undecafluorohexylamine, fluorinated poly(ß-amino ester) (FPAE) was synthesized to significantly improve the transfection performance, achieving high transfection efficiency of 87% and 55% in two representative difficult-to-transfect cells, HepG2 and Molt-4, which were cultured in adhesive and suspension condition, respectively. However, the potency of Lipofectamine 3000 was very limited. More importantly, functional studies revealed that FPAE can dramatically outperform Lipofectamine 3000 in delivering Bcl-xL and PKCßII to either provide the protection against apoptosis or promote the ferroptosis in HepG2 cells. This work facilitates gene therapies by overcoming biological barriers for targeting difficult-to-transfect cells and disease models when medically necessary.


Assuntos
Ferroptose , Humanos , Adesivos , Flúor , Transfecção , Apoptose
7.
Biosens Bioelectron ; 221: 114908, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36450168

RESUMO

Glucose detection is vital in the food industry for safety and quality management. As a healthy ingredient, the flavor of honey is frequently impacted by the crystallization of glucose. Therefore, determining the glucose level can offer precise reference data for the manufacture of honey. Various approaches have been tried, and the enzyme-based electrochemical analytical method is one of the most important and widely used strategies. However, there are still challenges for most electrochemical methods to achieve stable detection resistant to temperature variation due to the easy inactivation of the enzyme, the poor anti-interference capacity of the detection techniques and other influences from the external environment. Herein, a hydrogel-based electrochemical biosensor is proposed to stably detect glucose even at wide ranges of temperatures via electrochemical impedance spectroscopic (EIS) measurement. The key factor for stable detection relies on the metal-organic framework nanoparticles' protective layer to guarantee the robustness of glucose oxidase (GOx), thereby achieving stable and specific detection for glucose. Moreover, a cascade reaction-induced hydrogel formation in a 3D structure can be used as an impedance readout, which not only amplifies but also further stabilizes the GOx-induced response. The prepared hydrogel-based electrochemical biosensor showed a linear response to the glucose concentration in the range of 0.75-4 mg/mL. Furthermore, the biosensor has excellent anti-interference and temperature stability. High performance liquid chromatography analysis also validated the accuracy of this biosensor in detecting glucose in the honey sample.


Assuntos
Técnicas Biossensoriais , Glucose , Hidrogéis , Glucose Oxidase , Técnicas Eletroquímicas
8.
Front Public Health ; 11: 1270947, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38259731

RESUMO

Purpose: This study aimed to explore the effects of additional visual tasks in physical exercise on the vision and balance ability of children, and to verify whether children's vision mediated the influence of physical exercise on their balance ability. Methods: The study randomly selected 86 students aged 9-10 years old from a school in Suzhou city, dividing them into an experimental group (n = 43) and a control group (n = 43). The experimental group participated in physical exercise with additional visual tasks, while the control group engaged in routine physical exercise. The experiment lasted for 16 weeks, with kinetic visual acuity (KVA), uncorrected distance visual acuity (UDVA), static balance, and dynamic balance measured before and after the experiment. Results: The results showed that after the experiment, the experimental group had significantly improved kinetic visual acuity (KVA), uncorrected distance visual acuity (UDVA), static balance, and dynamic balance. In contrast, the control group had significantly decreased kinetic visual acuity, no significant improvement in uncorrected distance visual acuity, and no significant difference in dynamic balance and static balance. In the experimental group, there was a moderate positive correlation between kinetic visual acuity and uncorrected distance visual acuity, and a moderate positive correlation between uncorrected distance visual acuity and both static and dynamic balance. The study also found that uncorrected distance visual acuity partially mediated the effect of additional visual tasks during physical exercise on static and dynamic balance among children. Conclusion: In conclusion, adding visual tasks to physical exercise had a positive effect on improving children's vision and balance ability. Kinetic visual acuity and uncorrected distance visual acuity were positively correlated, and uncorrected distance visual acuity was positively correlated with both static and dynamic balance. Uncorrected distance visual acuity partially mediated the effect of physical exercise on children's balance ability.


Assuntos
Exercício Físico , Instituições Acadêmicas , Criança , Humanos , Acuidade Visual , Estudantes
9.
Anal Chem ; 94(49): 17312-17319, 2022 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-36446630

RESUMO

pH is one of the important parameters of a biological microenvironment, which is closely related to cell growth, development, vitality, division, and differentiation. Monitoring the pH of a microenvironment is helpful to monitor the cell metabolism as well as to understand the cellular life cycle. The sensitivity of liquid metals (LMs) to hydrogen ions has aroused our interest. Here, we propose a novel but facile pH sensor using liquid gallium (LM for short) droplet morphological change as the readout. The pH sensing characteristics of the LM droplet were examined, especially the shape response. LM can form solid native oxide skin rapidly in oxygenated solution, and the oxide layer will be removed in acidic or alkaline solutions, which will cause a great change in surface tension. The phenomenon is the change of LM morphology from macroscopic observation. We explored the electrochemical characteristics of LM at different pH values, explained the mechanism of surface change, and calibrated the relationship curve between LM morphology and pH and the interference of impurity ions on the sensor. Finally, we proposed a detection algorithm for the LM pH morphology sensor and tried to automatically detect pH with a mobile app, which was applied to the pH detection of cell culture solution. We believe that the response characteristics of LM to hydrogen ions have great potential in microenvironment detection.


Assuntos
Gálio , Prótons , Íons , Concentração de Íons de Hidrogênio , Óxidos
10.
Crit Rev Oncol Hematol ; 176: 103746, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35752425

RESUMO

Recently, immune checkpoint therapy (ICT) represented by programmed cell death1 (PD-1) and its major ligands, programmed death ligand 1 (PD-L1), has achieved significant success. Detection of PD-L1 by immunohistochemistry (IHC) is a classic method to guide the treatment of ICT patients. However, PD-L1 expression in the tumor microenvironment is highly complex. Thus, PD-L1 IHC is inadequate to fully understand the relevance of PD-L1 levels in the whole body and their dynamics to improve therapeutic outcomes. Intriguingly, numerous studies have revealed that molecular imaging technologies could potentially meet this need. Therefore, the purpose of this narrative review is to summarize the preclinical and clinical application of ICT guided by molecular imaging technology, and to explore the future opportunities and practical difficulties of these innovations.


Assuntos
Antígeno B7-H1 , Microambiente Tumoral , Humanos , Imuno-Histoquímica , Imagem Molecular , Prognóstico
11.
J Biol Chem ; 298(6): 101982, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35472330

RESUMO

Friedreich's ataxia (FRDA) is a degenerative disease caused by a decrease in the mitochondrial protein frataxin (Fxn), which is involved in iron-sulfur cluster (ISC) synthesis. Diminutions in Fxn result in decreased ISC synthesis, increased mitochondrial iron accumulation, and impaired mitochondrial function. Here, we show that conditions that result in increased mitochondrial reactive oxygen species in yeast or mammalian cell culture give rise to increased turnover of Fxn but not of other ISC synthesis proteins. We demonstrate that the mitochondrial Lon protease is involved in Fxn degradation and that iron export through the mitochondrial metal transporter Mmt1 protects yeast Fxn from degradation. We also determined that when FRDA fibroblasts were grown in media containing elevated iron, mitochondrial reactive oxygen species increased and Fxn decreased compared to WT fibroblasts. Furthermore, we screened a library of FDA-approved compounds and identified 38 compounds that increased yeast Fxn levels, including the azole bifonazole, antiparasitic fipronil, antitumor compound dibenzoylmethane, antihypertensive 4-hydroxychalcone, and a nonspecific anion channel inhibitor 4,4-diisothiocyanostilbene-2,2-sulfonic acid. We show that top hits 4-hydroxychalcone and dibenzoylmethane increased mRNA levels of transcription factor nuclear factor erythroid 2-related factor 2 in FRDA patient-derived fibroblasts, as well as downstream antioxidant targets thioredoxin, glutathione reductase, and superoxide dismutase 2. Taken together, these findings reveal that FRDA progression may be in part due to oxidant-mediated decreases in Fxn and that some approved compounds may be effective in increasing mitochondrial Fxn in FRDA, delaying disease progression.


Assuntos
Ataxia de Friedreich , Proteínas de Ligação ao Ferro , Animais , Ataxia de Friedreich/tratamento farmacológico , Ataxia de Friedreich/genética , Ataxia de Friedreich/metabolismo , Humanos , Ferro/metabolismo , Proteínas de Ligação ao Ferro/genética , Proteínas de Ligação ao Ferro/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Mamíferos/metabolismo , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Frataxina
12.
Sci Rep ; 11(1): 2011, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479321

RESUMO

In the intensively farmed, homogenous agricultural landscape of the North China Plain, family graveyards form distinct cultural landscape features. In addition to their cultural value, these graveyards represent semi-natural habitat islands whose potential roles in biodiversity conservation and ecological functioning has remained poorly understood. In this study, we investigated plant species richness on 199 family graveyards of different ages and sizes. In accordance with biogeography theory, both overall and insect-pollinated plant species richness increased with area and age of graveyards. Even small graveyards show a strong potential for conserving local plant richness, and a mosaic of both large and small family graveyards could play an important role in the conservation of farmland biodiversity and related ecosystem functions. The launch of agri-environmental measures that conserve and create semi-natural habitats, in turn benefitting agricultural biodiversity and ecological functioning, has proven difficult in China due to the shortage of dispensable arable land. Given the great value of family graveyards as semi-natural habitats reflected in our study, we propose to focus preliminary efforts on conserving these landscape features as existing, widespread and culturally important semi-natural habitat islands. This would represent an effective, complementary policy to a subsequent re-establishment of other semi-natural habitats for the conservation of biodiversity and ecological functioning in agricultural landscapes.

13.
ACS Appl Mater Interfaces ; 12(48): 53966-53972, 2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33179912

RESUMO

The ability to pattern planar and freestanding 3D metallic architectures would enable numerous applications, including flexible electronics, displays, sensors, and antennas. Low melting point metals, such as gallium, have recently drawn considerable attention especially in the fields of flexible and stretchable electronics and devices owing to its unique properties, such as excellent electrical conductivity and fluidity. However, the large surface tension, low viscosity, and large density pose great challenges to 3D printing of freestanding gallium structures in a large scale, which hinder its further applications. In this article, we first propose an electrochemically enabled embedded 3D printing (3e-3DP) method for creating planar and freestanding gallium wire-like structures assisted with supporting hydrogel. After an enhanced solidification process and the removal of hydrogel, various freestanding 2D and 3D wire-like structures are realized. By simply reassembling the gallium structure into soft elastomer, a gallium-based flexible conductor and a 3D-spiral pressure sensor are demonstrated. Above all, this study presents a brand-new and economical way for the fabrication of 2D and 3D freestanding gallium structures, which has great prospects in wide applications in flexible and stretchable electronics and devices.

14.
J Biol Chem ; 295(32): 11002-11020, 2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32518166

RESUMO

Mitochondrial iron import is essential for iron-sulfur cluster formation and heme biosynthesis. Two nuclear-encoded vertebrate mitochondrial high-affinity iron importers, mitoferrin1 (Mfrn1) and Mfrn2, have been identified in mammals. In mice, the gene encoding Mfrn1, solute carrier family 25 member 37 (Slc25a37), is highly expressed in sites of erythropoiesis, and whole-body Slc25a37 deletion leads to lethality. Here, we report that mice with a deletion of Slc25a28 (encoding Mfrn2) are born at expected Mendelian ratios, but show decreased male fertility due to reduced sperm numbers and sperm motility. Mfrn2-/- mice placed on a low-iron diet exhibited reduced mitochondrial manganese, cobalt, and zinc levels, but not reduced iron. Hepatocyte-specific loss of Slc25a37 (encoding Mfrn1) in Mfrn2-/- mice did not affect animal viability, but resulted in a 40% reduction in mitochondrial iron and reduced levels of oxidative phosphorylation proteins. Placing animals on a low-iron diet exaggerated the reduction in mitochondrial iron observed in liver-specific Mfrn1/2-knockout animals. Mfrn1-/-/Mfrn2-/- bone marrow-derived macrophages or skin fibroblasts in vitro were unable to proliferate, and overexpression of Mfrn1-GFP or Mfrn2-GFP prevented this proliferation defect. Loss of both mitoferrins in hepatocytes dramatically reduced regeneration in the adult mouse liver, further supporting the notion that both mitoferrins transport iron and that their absence limits proliferative capacity of mammalian cells. We conclude that Mfrn1 and Mfrn2 contribute to mitochondrial iron homeostasis and are required for high-affinity iron import during active proliferation of mammalian cells.


Assuntos
Proteínas de Transporte de Cátions/fisiologia , Proliferação de Células/fisiologia , Regeneração Hepática/fisiologia , Proteínas de Membrana Transportadoras/fisiologia , Animais , Homeostase , Ferro/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias Hepáticas/metabolismo
15.
J Biol Chem ; 295(6): 1716-1726, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-31896574

RESUMO

Budding yeast (Saccharomyces cerevisiae) responds to low cytosolic iron by up-regulating the expression of iron import genes; iron import can reflect iron transport into the cytosol or mitochondria. Mmt1 and Mmt2 are nuclearly encoded mitochondrial proteins that export iron from the mitochondria into the cytosol. Here we report that MMT1 and MMT2 expression is transcriptionally regulated by two pathways: the low-iron-sensing transcription factor Aft1 and the oxidant-sensing transcription factor Yap1. We determined that MMT1 and MMT2 expression is increased under low-iron conditions and decreased when mitochondrial iron import is increased through overexpression of the high-affinity mitochondrial iron importer Mrs3. Moreover, loss of iron-sulfur cluster synthesis induced expression of MMT1 and MMT2 We show that exposure to the oxidant H2O2 induced MMT1 expression but not MMT2 expression and identified the transcription factor Yap1 as being involved in oxidant-mediated MMT1 expression. We defined Aft1- and Yap1-dependent transcriptional sites in the MMT1 promoter that are necessary for low-iron- or oxidant-mediated MMT1 expression. We also found that the MMT2 promoter contains domains that are important for regulating its expression under low-iron conditions, including an upstream region that appears to partially repress expression under low-iron conditions. Our findings reveal that MMT1 and MMT2 are induced under low-iron conditions and that the low-iron regulator Aft1 is required for this induction. We further uncover an Aft1-binding site in the MMT1 promoter sufficient for inducing MMT1 transcription and identify an MMT2 promoter region required for low iron induction.


Assuntos
Proteínas de Transporte de Cátions/genética , Proteínas Mitocondriais/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Fatores de Transcrição/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Regulação Fúngica da Expressão Gênica , Ferro/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Saccharomyces cerevisiae/metabolismo , Ativação Transcricional
16.
Complement Ther Clin Pract ; 35: 121-125, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31003647

RESUMO

BACKGROUND AND PURPOSE: Postoperative rehabilitation plays an indispensable role for a successful total knee arthroplasty (TKA) and the optimal exercises programs are not known. A single-centre, single-blind, randomised controlled trial was designed to explore whether tai chi chuan (TCC) exercises can improve the functional outcomes and the quality of life (QOL) in patients with primary TKA due to knee osteoarthritis (OA). MATERIALS AND METHODS: One hundred seven participants with primary TKA for end-stage knee OA were enrolled from January 2014 to January 2017. Patients were treated for 12 weeks either with TCC exercises (intervention) or traditional physical exercises (control). Outcomes including western ontario and mcMaster universities arthritis index (WOMAC), 6-min walk test (6 MWT), knee range of motion (ROM), and short form (36) health survey (SF-36) were assessed. The adverse events related to TCC exercises or TKA were recorded. RESULTS: Before the intervention, the two groups were comparable after examining the general descriptions of patients. Compared with the control group (CG), the TCC group (TG) had significantly better scores in the WOMAC physical function score, 6 MWT, SF-36 physical component score (PCS), and the mental component score (MCS) (P < 0.05) after the 12-week intervention. Nevertheless, there were no significant differences in WOMAC pain score and knee ROM. There were no adverse events related to the TCC exercise program. In the CG, three patients reported one fall each, but those falls did not lead to a further problem. CONCLUSION: The TCC exercises improve the physical function and the QOL in patients with primary TKA without additional risks.


Assuntos
Artroplastia do Joelho , Osteoartrite do Joelho/reabilitação , Cuidados Pós-Operatórios/métodos , Qualidade de Vida , Tai Chi Chuan , Idoso , Feminino , Indicadores Básicos de Saúde , Humanos , Articulação do Joelho/fisiopatologia , Masculino , Osteoartrite do Joelho/fisiopatologia , Osteoartrite do Joelho/cirurgia , Estudos Prospectivos , Amplitude de Movimento Articular , Método Simples-Cego , Resultado do Tratamento
17.
J Biol Chem ; 293(51): 19797-19811, 2018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30366982

RESUMO

Erythropoietin (EPO) signaling is critical to many processes essential to terminal erythropoiesis. Despite the centrality of iron metabolism to erythropoiesis, the mechanisms by which EPO regulates iron status are not well-understood. To this end, here we profiled gene expression in EPO-treated 32D pro-B cells and developing fetal liver erythroid cells to identify additional iron regulatory genes. We determined that FAM210B, a mitochondrial inner-membrane protein, is essential for hemoglobinization, proliferation, and enucleation during terminal erythroid maturation. Fam210b deficiency led to defects in mitochondrial iron uptake, heme synthesis, and iron-sulfur cluster formation. These defects were corrected with a lipid-soluble, small-molecule iron transporter, hinokitiol, in Fam210b-deficient murine erythroid cells and zebrafish morphants. Genetic complementation experiments revealed that FAM210B is not a mitochondrial iron transporter but is required for adequate mitochondrial iron import to sustain heme synthesis and iron-sulfur cluster formation during erythroid differentiation. FAM210B was also required for maximal ferrochelatase activity in differentiating erythroid cells. We propose that FAM210B functions as an adaptor protein that facilitates the formation of an oligomeric mitochondrial iron transport complex, required for the increase in iron acquisition for heme synthesis during terminal erythropoiesis. Collectively, our results reveal a critical mechanism by which EPO signaling regulates terminal erythropoiesis and iron metabolism.


Assuntos
Células Eritroides/metabolismo , Eritropoetina/metabolismo , Ferroquelatase/metabolismo , Heme/biossíntese , Ferro/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Animais , Células Eritroides/citologia , Eritropoese , Células HEK293 , Humanos , Proteínas de Membrana/química , Camundongos , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/química , Transporte Proteico
18.
J Biol Chem ; 293(27): 10782-10795, 2018 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-29773647

RESUMO

Ergosterol synthesis is essential for cellular growth and viability of the budding yeast Saccharomyces cerevisiae, and intracellular sterol distribution and homeostasis are therefore highly regulated in this species. Erg25 is an iron-containing C4-methyl sterol oxidase that contributes to the conversion of 4,4-dimethylzymosterol to zymosterol, a precursor of ergosterol. The ERG29 gene encodes an endoplasmic reticulum (ER)-associated protein, and here we identified a role for Erg29 in the methyl sterol oxidase step of ergosterol synthesis. ERG29 deletion resulted in lethality in respiring cells, but respiration-incompetent (Rho- or Rho0) cells survived, suggesting that Erg29 loss leads to accumulation of oxidized sterol metabolites that affect cell viability. Down-regulation of ERG29 expression in Δerg29 cells indeed led to accumulation of methyl sterol metabolites, resulting in increased mitochondrial oxidants and a decreased ability of mitochondria to synthesize iron-sulfur (Fe-S) clusters due to reduced levels of Yfh1, the mammalian frataxin homolog, which is involved in mitochondrial iron metabolism. Using a high-copy genomic library, we identified suppressor genes that permitted growth of Δerg29 cells on respiratory substrates, and these included genes encoding the mitochondrial proteins Yfh1, Mmt1, Mmt2, and Pet20, which reversed all phenotypes associated with loss of ERG29 Of note, loss of Erg25 also resulted in accumulation of methyl sterol metabolites and also increased mitochondrial oxidants and degradation of Yfh1. We propose that accumulation of toxic intermediates of the methyl sterol oxidase reaction increases mitochondrial oxidants, which affect Yfh1 protein stability. These results indicate an interaction between sterols generated by ER proteins and mitochondrial iron metabolism.


Assuntos
Proteínas Ferro-Enxofre/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Esteróis/metabolismo , Homeostase , Proteínas Ferro-Enxofre/genética , Proteínas Mitocondriais/genética , Oxirredução , Fenótipo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/genética
19.
Curr Genet ; 64(2): 413-416, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29043483

RESUMO

All eukaryotes require the transition metal, iron, a redox active element that is an essential cofactor in many metabolic pathways, as well as an oxygen carrier. Iron can also react to generate oxygen radicals such as hydroxyl radicals and superoxide anions, which are highly toxic to cells. Therefore, organisms have developed intricate mechanisms to acquire iron as well as to protect themselves from the toxic effects of excess iron. In fungi and plants, iron is stored in the vacuole as a protective mechanism against iron toxicity. Iron storage in the vacuole is mediated predominantly by the vacuolar metal importer Ccc1 in yeast and the homologous transporter VIT1 in plants. Transcription of yeast CCC1 expression is tightly controlled primarily by the transcription factor Yap5, which sits on the CCC1 promoter and activates transcription through the binding of Fe-S clusters. A second mechanism that regulates CCC1 transcription is through the Snf1 signaling pathway involved in low-glucose sensing. Snf1 activates stress transcription factors Msn2 and Msn4 to mediate CCC1 transcription. Transcriptional regulation by Yap5 and Snf1 are completely independent and provide for a graded response in Ccc1 expression. The identification of multiple independent transcriptional pathways that regulate the levels of Ccc1 under high iron conditions accentuates the importance of protecting cells from the toxic effects of high iron.


Assuntos
Proteínas de Transporte de Cátions/genética , Ferro/toxicidade , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Vacúolos/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Proteínas de Transporte de Cátions/metabolismo , Proteínas de Ligação a DNA/genética , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Vacúolos/efeitos dos fármacos , Vacúolos/metabolismo
20.
J Biol Chem ; 292(37): 15577-15586, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28760824

RESUMO

The budding yeast Saccharomyces cerevisiae stores iron in the vacuole, which is a major resistance mechanism against iron toxicity. One key protein involved in vacuolar iron storage is the iron importer Ccc1, which facilitates iron entry into the vacuole. Transcription of the CCC1 gene is largely regulated by the binding of iron-sulfur clusters to the activator domain of the transcriptional activator Yap5. Additional evidence, however, suggests that Yap5-independent transcriptional activation of CCC1 also contributes to iron resistance. Here, we demonstrate that components of the signaling pathway involving the low-glucose sensor Snf1 regulate CCC1 transcription and iron resistance. We found that SNF1 deletion acts synergistically with YAP5 deletion to regulate CCC1 transcription and iron resistance. A kinase-dead mutation of Snf1 lowered iron resistance as did deletion of SNF4, which encodes a partner protein of Snf1. Deletion of all three alternative partners of Snf1 encoded by SIT1, SIT2, and GAL83 decreased both CCC1 transcription and iron resistance. The Snf1 complex is known to activate the general stress transcription factors Msn2 and Msn4. We show that Msn2 and Msn4 contribute to Snf1-mediated CCC1 transcription. Of note, SNF1 deletion in combination with MSN2 and MSN4 deletion resulted in additive effects on CCC1 transcription, suggesting that other activators contribute to the regulation of CCC1 transcription. In conclusion, we show that yeast have developed multiple transcriptional mechanisms to regulate Ccc1 expression and to protect against high cytosolic iron toxicity.


Assuntos
Proteínas de Transporte de Cátions/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação Fúngica da Expressão Gênica , Estresse Oxidativo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Fatores de Transcrição/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Transporte Biológico/efeitos dos fármacos , Proteínas de Transporte de Cátions/genética , Deleção de Genes , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Ferro/metabolismo , Ferro/toxicidade , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Viabilidade Microbiana , Mutação , Oxidantes/metabolismo , Oxidantes/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/genética , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/genética , Transdução de Sinais/efeitos dos fármacos , Fatores de Transcrição/genética , Vacúolos/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA