Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Mil Med Res ; 10(1): 58, 2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-38017571

RESUMO

Latent tuberculosis infection (LTBI) has become a major source of active tuberculosis (ATB). Although the tuberculin skin test and interferon-gamma release assay can be used to diagnose LTBI, these methods can only differentiate infected individuals from healthy ones but cannot discriminate between LTBI and ATB. Thus, the diagnosis of LTBI faces many challenges, such as the lack of effective biomarkers from Mycobacterium tuberculosis (MTB) for distinguishing LTBI, the low diagnostic efficacy of biomarkers derived from the human host, and the absence of a gold standard to differentiate between LTBI and ATB. Sputum culture, as the gold standard for diagnosing tuberculosis, is time-consuming and cannot distinguish between ATB and LTBI. In this article, we review the pathogenesis of MTB and the immune mechanisms of the host in LTBI, including the innate and adaptive immune responses, multiple immune evasion mechanisms of MTB, and epigenetic regulation. Based on this knowledge, we summarize the current status and challenges in diagnosing LTBI and present the application of machine learning (ML) in LTBI diagnosis, as well as the advantages and limitations of ML in this context. Finally, we discuss the future development directions of ML applied to LTBI diagnosis.


Assuntos
Tuberculose Latente , Tuberculose , Humanos , Tuberculose Latente/diagnóstico , Inteligência Artificial , Epigênese Genética , Tuberculose/diagnóstico , Aprendizado de Máquina , Biomarcadores
2.
Proteomics ; 15(7): 1259-67, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25421965

RESUMO

Prolyl hydroxylation is a PTM that plays an important role in the formation of collagen fibrils and in the oxygen-dependent regulation of hypoxia inducible factor-α (HIF-α). While this modification has been well characterized in the context of these proteins, it remains unclear to what extent it occurs in the remaining mammalian proteome. We explored this question using MS to analyze cellular extracts subjected to various fractionation strategies. In one strategy, we employed the von Hippel Lindau tumor suppressor protein, which recognizes prolyl hydroxylated HIF-α, as a scaffold for generating hydroxyproline capture reagents. We report novel sites of prolyl hydroxylation within five proteins: FK506-binding protein 10, myosin heavy chain 10, hexokinase 2, pyruvate kinase, and C-1 Tetrahydrofolate synthase. Furthermore, we show that identification of prolyl hydroxylation presents a significant technical challenge owing to widespread isobaric methionine oxidation, and that manual inspection of spectra of modified peptides in this context is critical for validation.


Assuntos
Processamento de Proteína Pós-Traducional , Proteoma/metabolismo , Sequência de Aminoácidos , Cromatografia em Gel , Células HeLa , Humanos , Hidroxilação , Anotação de Sequência Molecular , Prolina/química , Proteoma/química , Proteoma/isolamento & purificação , Espectrometria de Massas em Tandem
3.
J Biol Chem ; 289(21): 14656-65, 2014 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-24711448

RESUMO

The Tibetan population has adapted to the chronic hypoxia of high altitude. Tibetans bear a genetic signature in the prolyl hydroxylase domain protein 2 (PHD2/EGLN1) gene, which encodes for the central oxygen sensor of the hypoxia-inducible factor (HIF) pathway. Recent studies have focused attention on two nonsynonymous coding region substitutions, D4E and C127S, both of which are markedly enriched in the Tibetan population. These amino acids reside in a region of PHD2 that harbors a zinc finger, which we have previously discovered binds to a Pro-Xaa-Leu-Glu (PXLE) motif in the HSP90 cochaperone p23, thereby recruiting PHD2 to the HSP90 pathway to facilitate HIF-α hydroxylation. We herein report that the Tibetan PHD2 haplotype (D4E/C127S) strikingly diminishes the interaction of PHD2 with p23, resulting in impaired PHD2 down-regulation of the HIF pathway. The defective binding to p23 depends on both the D4E and C127S substitutions. We also identify a PXLE motif in HSP90 itself that can mediate binding to PHD2 but find that this interaction is maintained with the D4E/C127S PHD2 haplotype. We propose that the Tibetan PHD2 variant is a loss of function (hypomorphic) allele, leading to augmented HIF activation to facilitate adaptation to high altitude.


Assuntos
Altitude , Prolina Dioxigenases do Fator Induzível por Hipóxia/metabolismo , Oxirredutases Intramoleculares/metabolismo , Oxigênio/metabolismo , Adaptação Fisiológica , Motivos de Aminoácidos/genética , Sequência de Aminoácidos , Animais , Western Blotting , Hipóxia Celular , Células Cultivadas , Embrião de Mamíferos/citologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Células HEK293 , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Haplótipos , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Prolina Dioxigenases do Fator Induzível por Hipóxia/genética , Oxirredutases Intramoleculares/genética , Camundongos , Camundongos Knockout , Polimorfismo de Nucleotídeo Único , Prostaglandina-E Sintases , Ligação Proteica , Tibet
4.
J Biol Chem ; 288(14): 9662-9674, 2013 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-23413029

RESUMO

Prolyl hydroxylase domain protein 2 (PHD2, also known as Egg Laying Defective Nine homolog 1) is a key oxygen-sensing protein in metazoans. In an oxygen-dependent manner, PHD2 site-specifically prolyl hydroxylates the master transcription factor of the hypoxic response, hypoxia-inducible factor-α (HIF-α), thereby targeting HIF-α for degradation. In this report we show that the heat shock protein 90 (HSP90) co-chaperones p23 and FKBP38 interact via a conserved Pro-Xaa-Leu-Glu motif (where Xaa = any amino acid) in these proteins with the N-terminal Myeloid Nervy and DEAF-1 (MYND)-type zinc finger of PHD2. Knockdown of p23 augments hypoxia-induced HIF-1α protein levels and HIF target genes. We propose that p23 recruits PHD2 to the HSP90 machinery to facilitate HIF-1α hydroxylation. These findings identify a link between two ancient pathways, the PHD:HIF and the HSP90 pathways, and suggest that this link was established concurrent with the emergence of the PHD:HIF pathway in evolution.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/química , Pró-Colágeno-Prolina Dioxigenase/fisiologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Linhagem Celular Tumoral , Células HEK293 , Células HeLa , Humanos , Hipóxia , Prolina Dioxigenases do Fator Induzível por Hipóxia , Espectrometria de Massas/métodos , Modelos Biológicos , Dados de Sequência Molecular , Plasmídeos/metabolismo , Pró-Colágeno-Prolina Dioxigenase/química , Pró-Colágeno-Prolina Dioxigenase/metabolismo , Estrutura Terciária de Proteína , RNA Interferente Pequeno/metabolismo
5.
J Biol Chem ; 281(17): 11456-63, 2006 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-16469750

RESUMO

Type-II NADH-menaquinone oxidoreductase (NDH-2) is an essential respiratory enzyme of the pathogenic bacterium Mycobacterium tuberculosis (Mtb) that plays a pivotal role in its growth. In the present study, we expressed and purified highly active Mtb NDH-2 using a Mycobacterium smegmatis expression system, and the steady-state kinetics and inhibitory actions of phenothiazines were characterized. Purified NDH-2 contains a non-covalently bound flavin adenine dinucleotide cofactor and oxidizes NADH with quinones but does not react with either NADPH or oxygen. Ubiquinone-2 (Q2) and decylubiquinone showed high electron-accepting activity, and the steady-state kinetics and the NADH-Q2 oxidoreductase reaction were found to operate by a ping-pong reaction mechanism. Phenothiazine analogues, trifluoperazine, Compound 1, and Compound 2 inhibit the NADH-Q2 reductase activity with IC50 = 12, 11, and 13 microm, respectively. Trifluoperazine inhibition is non-competitive for NADH, whereas the inhibition kinetics is found to be uncompetitive in terms of Q2.


Assuntos
Antituberculosos/farmacologia , Inibidores Enzimáticos/farmacologia , Mycobacterium tuberculosis/enzimologia , NAD/metabolismo , Fenotiazinas/farmacologia , Quinona Redutases/antagonistas & inibidores , Ligação Competitiva , Flavina-Adenina Dinucleotídeo/metabolismo , Cinética , Quinona Redutases/metabolismo , Quinonas/química , Ubiquinona/análogos & derivados , Ubiquinona/metabolismo
6.
Proc Natl Acad Sci U S A ; 102(12): 4548-53, 2005 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-15767566

RESUMO

Mycobacterium tuberculosis (Mtb) is an obligate aerobe that is capable of long-term persistence under conditions of low oxygen tension. Analysis of the Mtb genome predicts the existence of a branched aerobic respiratory chain terminating in a cytochrome bd system and a cytochrome aa(3) system. Both chains can be initiated with type II NADH:menaquinone oxidoreductase. We present a detailed biochemical characterization of the aerobic respiratory chains from Mtb and show that phenothiazine analogs specifically inhibit NADH:menaquinone oxidoreductase activity. The emergence of drug-resistant strains of Mtb has prompted a search for antimycobacterial agents. Several phenothiazines analogs are highly tuberculocidal in vitro, suppress Mtb growth in a mouse model of acute infection, and represent lead compounds that may give rise to a class of selective antibiotics.


Assuntos
Antituberculosos/farmacologia , Inibidores Enzimáticos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , Quinona Redutases/antagonistas & inibidores , Animais , Antituberculosos/química , Transporte de Elétrons/genética , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Inibidores Enzimáticos/química , Escherichia coli/genética , Feminino , Genes Bacterianos , Camundongos , Camundongos Endogâmicos BALB C , Mycobacterium tuberculosis/genética , Consumo de Oxigênio/efeitos dos fármacos , Fenotiazinas/química , Fenotiazinas/farmacologia , Quinona Redutases/genética , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/genética , Tuberculose Pulmonar/tratamento farmacológico , Tuberculose Pulmonar/microbiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...