RESUMEN
Trichosporon asahii is a pathogenic yeast that cause trichosporonosis. T. asahii exhibits several colony morphologies, such as white (W)- or off-white (O)-type, which may affect virulence. In this study, we compared the expression pattern of heparin-binding proteins in various colony morphologies and identified heparin-binding protein in T. asahii. Surface plasmon resonance analysis revealed that cell surface molecules attached more strongly to heparin in W- than O-type cells. We purified and identified a heparin-binding protein strongly expressed in W-type cells using heparin-Sepharose beads, named it heparin-binding protein 1 (HepBP1), and expressed Flag-tagged HepBP1 in mammalian cells. The heparin-binding ability of Flag-tagged HepBP1 was confirmed by pulldown assay using heparin-Sepharose beads. Thus, HepBP1 is a heparin-binding protein on T. asahii cell surface. These results suggest that several T. asahii cell surface proteins interact with glycosaminoglycans; therefore, they could contribute to infection.
Asunto(s)
Heparina , Heparina/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Unión Proteica , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Tricosporonosis/microbiología , Humanos , Resonancia por Plasmón de Superficie , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Membrana Celular/metabolismo , BasidiomycotaRESUMEN
Mitophagy/autophagy plays a protective role in various forms of liver damage, by renovating cellular metabolism linking to sustain liver homeostasis. A characterized pathway for mitophagy is the phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1)/Parkin-dependent signaling pathway. In particular, PINK1-mediated mitophagy could play an indispensable role in improving the metabolic dysfunction-associated fatty liver disease (MAFLD) which could precede to steatohepatitis (NASH), fibrosis, and hepatocellular carcinoma. In addition, the PI3K/AKT/mTOR pathway might regulate the various characteristics of cellular homeostasis including energy metabolism, cell proliferation, and/or cell protection. Therefore, targeting mitophagy with the alteration of PI3K/AKT/mTOR or PINK1/Parkin-dependent signaling to eliminate impaired mitochondria might be an attractive strategy for the treatment of MAFLD. In particular, the efficacy of prebiotics for the treatment of MAFLD has been suggested to be useful via the modulation of the PI3K/AKT/mTOR/AMPK pathway. Additionally, several edible phytochemicals could activate mitophagy for the improvement of mitochondrial damages, which could also be a promising option to treat MAFLD with providing liver protection. Here, the potential therapeutics with several phytochemicals has been discussed for the treatment of MAFLD. Tactics with a viewpoint of prospective probiotics might contribute to the development of therapeutic interventions.
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Mitofagia , Enfermedad del Hígado Graso no Alcohólico , Humanos , Mitofagia/fisiología , Prebióticos , Enfermedad del Hígado Graso no Alcohólico/tratamiento farmacológico , Fosfatidilinositol 3-Quinasas , Estudios Prospectivos , Proteínas Proto-Oncogénicas c-akt , Especies Reactivas de Oxígeno/metabolismo , Serina-Treonina Quinasas TOR , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
The tryptophan and kynurenine pathway is well-known to play an important role in nervous, endocrine, and immune systems, as well as in the development of inflammatory diseases. It has been documented that some kynurenine metabolites are considered to have anti-oxidative, anti-inflammatory, and/or neuroprotective properties. Importantly, many of these kynurenine metabolites may possess immune-regulatory properties that could alleviate the inflammation response. The abnormal activation of the tryptophan and kynurenine pathway might be involved in the pathophysiological process of various immune-related diseases, such as inflammatory bowel disease, cardiovascular disease, osteoporosis, and/or polycystic ovary syndrome. Interestingly, kynurenine metabolites may be involved in the brain memory system and/or intricate immunity via the modulation of glial function. In the further deliberation of this concept with engram, the roles of gut microbiota could lead to the development of remarkable treatments for the prevention of and/or the therapeutics for various intractable immune-related diseases.
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Microbioma Gastrointestinal , Enfermedades del Sistema Inmune , Femenino , Humanos , Triptófano/metabolismo , Quinurenina/metabolismo , Encéfalo/metabolismo , Enfermedades del Sistema Inmune/metabolismoRESUMEN
Microbiome dysbiosis resulting in altered metabolite profiles may be associated with certain diseases, including inflammatory bowel diseases (IBD), which are characterized by active intestinal inflammation. Several studies have indicated the beneficial anti-inflammatory effect of metabolites from gut microbiota, such as short-chain fatty acids (SCFAs) and/or D-amino acids in IBD therapy, through orally administered dietary supplements. In the present study, the potential gut protective effects of d-methionine (D-Met) and/or butyric acid (BA) have been investigated in an IBD mouse model. We have also built an IBD mouse model, which was cost-effectively induced with low molecular weight DSS and kappa-carrageenan. Our findings revealed that D-Met and/or BA supplementation resulted in the attenuation of the disease condition as well as the suppression of several inflammation-related gene expressions in the IBD mouse model. The data shown here may suggest a promising therapeutic potential for improving symptoms of gut inflammation with an impact on IBD therapy. However, molecular metabolisms need to be further explored.
Asunto(s)
Colitis Ulcerosa , Colitis , Enfermedades Inflamatorias del Intestino , Ratones , Animales , Carragenina/efectos adversos , Colitis Ulcerosa/inducido químicamente , Colitis Ulcerosa/tratamiento farmacológico , Metionina , Ácido Butírico/farmacología , Enfermedades Inflamatorias del Intestino/metabolismo , Inflamación , Racemetionina , Sulfato de Dextran/toxicidad , Colitis/inducido químicamente , Modelos Animales de Enfermedad , Ratones Endogámicos C57BLRESUMEN
PURPOSE: Psychological stress could negatively influence female reproductive ability. d-Leucine (d-Leu) is a d-type amino acid found in foods and mammalian tissues. We have examined the protective effects of d-Leu on oocyte abnormality induced by psychological stress. METHODS: Female mice (6-week-old) were divided into three groups: control, restraint stress (RS), and RS/d-Leu. The RS and RS/d-Leu mice were holed for 3 hours daily during 14 days. RS/d-Leu mice were fed 0.3% d-Leu diet. The oocyte maturation failure was analyzed by shapes of spindles and chromosomes. In addition, levels of heme-oxygenase-1 (HO-1) and superoxide dismutase (SOD) expression in the ovaries were also examined. Whether d-Leu reduces the generation of reactive oxygen species (ROS) in cultured cells, K562 cells were treated with d-Leu, and then ROS in K562 were analyzed. RESULTS: Oocyte maturation failure was increased in RS mice. d-Leu reduced abnormal oocytes to control level. The expression levels of HO-1 and SOD2 increased in RS/d-Leu mice compared to those of RS mice. ROS levels were decreased in K562 cells with d-Leu in a dose-dependent manner. CONCLUSIONS: We concluded that d-Leu protects oocytes from psychological stress through the induction of HO-1 and SOD2 expression then by reducing oxidative stress.
RESUMEN
Lamellipodia are sheet-like cell protrusions driven by actin polymerization mainly through Rac1, a GTPase molecular switch. In Fcγ receptor-mediated phagocytosis of IgG-opsonized erythrocytes (IgG-Es), Rac1 activation is required for lamellipodial extension along the surface of IgG-Es. However, the significance of Rac1 deactivation in phagosome formation is poorly understood. Our live-cell imaging and electron microscopy revealed that RAW264 macrophages expressing a constitutively active Rac1 mutant showed defects in phagocytic cup formation, while lamellipodia were formed around IgG-Es. Because activated Rac1 reduced the phosphorylation levels of myosin light chains, failure of the cup formation is probably due to inhibition of actin/myosin II contractility. Reversible photo-manipulation of the Rac1 switch in macrophages fed with IgG-Es could phenocopy two lamellipodial motilities: outward-extension and cup-constriction by Rac1 ON and OFF, respectively. In conjunction with fluorescence resonance energy transfer imaging of Rac1 activity, we provide a novel mechanistic model of phagosome formation spatiotemporally controlled by Rac1 switching within a phagocytic cup.
Asunto(s)
Macrófagos/inmunología , Modelos Inmunológicos , Neuropéptidos/inmunología , Fagosomas/inmunología , Receptores de IgG/inmunología , Proteína de Unión al GTP rac1/inmunología , Animales , Ratones , Fosforilación/inmunología , Células RAW 264.7RESUMEN
Macropinocytosis is a highly conserved endocytic process by which extracellular fluid and solutes are internalized into cells. Macropinocytosis starts with the formation of membrane ruffles at the plasma membrane and ends with their closure. The transient and sequential emergence of phosphoinositides PI(3,4,5)P3 and PI(3,4)P2 in the membrane ruffles is essential for macropinocytosis. By making use of information in the Caenorhabditis elegans mutants defective in fluid-phase endocytosis, we found that mammalian phosphoinositide phosphatase MTMR6 that dephosphorylates PI(3)P to PI, and its binding partner MTMR9, are required for macropinocytosis. INPP4B, which dephosphorylates PI(3,4)P2 to PI(3)P, was also found to be essential for macropinocytosis. These phosphatases operate after the formation of membrane ruffles to complete macropinocytosis. Finally, we showed that KCa3.1, a Ca(2+)-activated K(+) channel that is activated by PI(3)P, is required for macropinocytosis. We propose that the sequential breakdown of PI(3,4,5)P3 â PI(3,4)P2 â PI(3)P â PI controls macropinocytosis through specific effectors of the intermediate phosphoinositides.
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Caenorhabditis elegans/fisiología , Fosfatos de Fosfatidilinositol/metabolismo , Monoéster Fosfórico Hidrolasas/metabolismo , Pinocitosis/fisiología , Proteínas Tirosina Fosfatasas no Receptoras/metabolismo , Animales , Caenorhabditis elegans/metabolismo , Línea Celular , Cartilla de ADN/genética , Humanos , Microscopía Electrónica de Rastreo , Microscopía Fluorescente , Fosforilación , Interferencia de ARN , ARN Interferente Pequeño/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
XL147 (SAR245408, pilaralisib), an ATP-competitive pan-class I phosphoinositide 3-kinase (PI3K) inhibitor, is a promising new anticancer drug. We examined the effect of the PI3K inhibitor on PC3 prostate cancer cells under a fluorescence microscope and found that XL147-treated cancer cells are rapidly injured by blue wavelength (430 nm) light irradiation. During the irradiation, the cancer cells treated with 0.2-2 µM XL147 showed cell surface blebbing and cytoplasmic vacuolation and died within 15 min. The extent of cell injury/death was dependent on the dose of XL147 and the light power of the irradiation. These findings suggest that XL147 might act as a photosensitizing reagent in photodynamic therapy (PDT) for cancer. Moreover, the cytotoxic effect of photosensitized XL147 was reduced by pretreatment with other ATP-competitive PI3K inhibitors such as LY294002, suggesting that the cytotoxic effect of photosensitized XL147 is facilitated by binding to PI3K in cells. In a single-cell illumination analysis using a fluorescent probe to identify reactive oxygen species (ROS), significantly increased ROS production was observed in the XL147-treated cells when the cell was illuminated with blue light. Taken together, it is conceivable that XL147, which is preferentially accumulated in cancer cells, could be photosensitized by blue light to produce ROS to kill cancer cells. This study will open up new possibilities for PDT using anticancer drugs.
Asunto(s)
Antineoplásicos/farmacología , Luz , Neoplasias/metabolismo , Neoplasias/terapia , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fotoquimioterapia , Fármacos Fotosensibilizantes/uso terapéutico , Animales , Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , Línea Celular Tumoral , Cromonas/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Macrófagos/efectos de la radiación , Ratones , Imagen Molecular , Morfolinas/farmacología , Fotoquimioterapia/métodos , Quinoxalinas/farmacología , Especies Reactivas de Oxígeno/metabolismo , Sulfonamidas/farmacologíaRESUMEN
Translational control of transcription factor ATF4 through paired upstream ORFs (uORFs) plays an important role in eukaryotic gene regulation. While it is typically induced by phosphorylation of eIF2α, ATF4 translation can be also induced by expression of a translational inhibitor protein, eIF5-mimic protein 1 (5MP1, also known as BZW2) in mammals. Here we show that the 5MP gene is maintained in eukaryotes under strong purifying selection, but is uniquely missing in two major phyla, nematoda and ascomycota. The common function of 5MP from protozoa, plants, fungi and insects is to control translation by inhibiting eIF2. The affinity of human 5MP1 to eIF2ß was measured as being equivalent to the published value of human eIF5 to eIF2ß, in agreement with effective competition of 5MP with eIF5 for the main substrate, eIF2. In the red flour beetle, Tribolium castaneum, RNA interference studies indicate that 5MP facilitates expression of GADD34, a downstream target of ATF4. Furthermore, both 5MP and ATF4 are essential for larval development. Finally, 5MP and the paired uORFs allowing ATF4 control are conserved in the entire metazoa except nematoda. Based on these findings, we discuss the phylogenetic and functional linkage between ATF4 regulation and 5MP expression in this group of eukaryotes.
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Factor de Transcripción Activador 4/genética , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica , Biosíntesis de Proteínas , Factor de Transcripción Activador 4/biosíntesis , Animales , Proteínas de Unión al ADN/clasificación , Proteínas de Unión al ADN/fisiología , Factor 2 Eucariótico de Iniciación/antagonistas & inhibidores , Factor 2 Eucariótico de Iniciación/metabolismo , Factor 5 Eucariótico de Iniciación/metabolismo , Humanos , Proteínas de Insectos/metabolismo , Sistemas de Lectura Abierta , Filogenia , Proteína Fosfatasa 1/metabolismo , Saccharomyces cerevisiae/metabolismo , Tribolium/enzimología , Tribolium/genética , Tribolium/crecimiento & desarrolloRESUMEN
Reports of cow's milk allergy (CMA) after neonatal gastrointestinal surgery have recently increased. In recent years it has been suggested that the development of CMA after gastrointestinal surgery in newborn infants is due to an immune function. In addition, the development of CMA might be synergistically exacerbated by congenital abnormalities of the intestinal mucosa, general conditional changes and local damage to the intestine by invasive surgery, and poor pre- or post-surgical nutrition. CMA manifests as a variety of symptoms, such as mild vomiting and bloody stool, decreased activity, poor oral intake, and ileus. CMA may also rarely cause gastrointestinal perforation. Here, we report the case of a newborn infant who developed CMA following repair of focal small intestinal perforation, in which eosinophilic enteritis was suspected to be a possible cause of anastomosis leakage.
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Enteritis/diagnóstico , Eosinofilia/diagnóstico , Gastritis/diagnóstico , Estenosis Hipertrófica del Piloro/diagnóstico , Animales , Diagnóstico Diferencial , Endoscopía del Sistema Digestivo/métodos , Nutrición Enteral/métodos , Enteritis/etiología , Enteritis/patología , Enteritis/terapia , Eosinofilia/etiología , Eosinofilia/patología , Eosinofilia/terapia , Femenino , Obstrucción de la Salida Gástrica/diagnóstico , Obstrucción de la Salida Gástrica/etiología , Gastritis/etiología , Gastritis/patología , Gastritis/terapia , Humanos , Recién Nacido , Leche/efectos adversos , Hipersensibilidad a la Leche/complicaciones , Hipersensibilidad a la Leche/diagnóstico , Vómitos/etiologíaRESUMEN
Many investigations have evaluated the expression of noncoding RNAs (ncRNAs) as well as their related molecular functions and biological machineries in individuals with alcohol dependence. Alcohol dependence may be one of the most prevailing psychological disorders globally, and its pathogenesis is intricate and inadequately comprehended. There is substantial evidence indicating significant links between multiple genetic factors and the development of alcohol dependence. In particular, the critical roles of ncRNAs have been emphasized in the pathology of mental illnesses, probably including alcohol dependence. In the comprehension of the action of ncRNAs and their machineries of modification, furthermore, they have emerged as therapeutic targets for a variety of psychiatric illnesses, including alcohol dependence. It is worth mentioning that the dysregulated expression of ncRNAs has been regularly detected in individuals with alcohol dependence. An in-depth knowledge of the roles of ncRNAs and m6A modification may be valuable for the development of a novel treatment against alcohol dependence. In general, a more profound understanding of the practical roles of ncRNAs might make important contributions to the precise diagnosis and/or actual management of alcohol dependence. Here, in this review, we mostly focused on up-to-date knowledge regarding alterations and/or modifications in the expression of ncRNAs in individuals with alcohol dependence. Then, we present prospects for future research and therapeutic applications with a novel concept of the engram system.
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Alcoholismo , Microbioma Gastrointestinal , ARN no Traducido , Humanos , Alcoholismo/genética , Alcoholismo/microbiología , Microbioma Gastrointestinal/genética , ARN no Traducido/genética , AnimalesRESUMEN
Polycystic kidney disease (PKD) is the most common genetic form of chronic kidney disease (CKD), and it involves the development of multiple kidney cysts. Not enough medical breakthroughs have been made against PKD, a condition which features regional hypoxia and activation of the hypoxia-inducible factor (HIF) pathway. The following pathology of CKD can severely instigate kidney damage and/or renal failure. Significant evidence verifies an imperative role for mitophagy in normal kidney physiology and the pathology of CKD and/or PKD. Mitophagy serves as important component of mitochondrial quality control by removing impaired/dysfunctional mitochondria from the cell to warrant redox homeostasis and sustain cell viability. Interestingly, treatment with the peroxisome proliferator-activated receptor-α (PPAR-α) agonist could reduce the pathology of PDK and might improve the renal function of the disease via the modulation of mitophagy, as well as the condition of gut microbiome. Suitable modulation of mitophagy might be a favorable tactic for the prevention and/or treatment of kidney diseases such as PKD and CKD.
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Enfermedades Renales Poliquísticas , Insuficiencia Renal Crónica , Humanos , Mitofagia/genética , Enfermedades Renales Poliquísticas/terapia , Enfermedades Renales Poliquísticas/metabolismo , Enfermedades Renales Poliquísticas/patología , Hipoxia , Oxidación-ReducciónRESUMEN
Noncoding RNAs (ncRNAs), including circular RNAs (circRNAs) and N6-methyladenosine (m6A), have been shown to play a critical role in the development of various diseases including obesity and metabolic disorder-associated fatty liver disease (MAFLD). Obesity is a chronic disease caused by excessive fat accumulation in the body, which has recently become more prevalent and is the foremost risk factor for MAFLD. Causes of obesity may involve the interaction of genetic, behavioral, and social factors. m6A RNA methylation might add a novel inspiration for understanding the development of obesity and MAFLD with post-transcriptional regulation of gene expression. In particular, circRNAs, microRNAs (miRNAs), and m6A might be implicated in the progression of MAFLD. Interestingly, m6A modification can modulate the translation, degradation, and other functions of ncRNAs. miRNAs/circRNAs can also modulate m6A modifications by affecting writers, erasers, and readers. In turn, ncRNAs could modulate the expression of m6A regulators in different ways. However, there is limited evidence on how these ncRNAs and m6A interact to affect the promotion of liver diseases. It seems that m6A can occur in DNA, RNA, and proteins that may be associated with several biological properties. This study provides a mechanistic understanding of the association of m6A modification and ncRNAs with liver diseases, especially for MAFLD. Comprehension of the association between m6A modification and ncRNAs may contribute to the development of treatment tactics for MAFLD.
RESUMEN
Chitosan seems to be an innovative biological material potentially utilized as a nanoparticle carrier for drug delivery, which could be low toxic, biocompatible, and easy to prepare. Chitosan nanoparticles have been employed in gene delivery. As a type of multifunctional adjuvant, chitosan nanoparticles could activate the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway to induce cell protection and/or proliferation via the modulation of autophagy within dendritic cells. In general, adjuvants may improve the innate and/or adaptive immune responses to a vaccine antigen by facilitating the antigen presentation of antigen presenting cells such as dendritic cells. The choice of a suitable adjuvant has become vital for improved safety and/or expanded application of vaccines. Fortunately, chitosan nanoparticles could be designed to target the dendritic cells to be enhanced by its adjuvant effect and for stimulating robust immune responses. Therefore, chitosan nanoparticles may be a good immune stimulant with encouraging properties for the development of superior vaccine delivery. Indeed, vaccines could play a key role in human health. In this review, we summarize the concept and/or recent progress in the field of chitosan nanoparticles, providing a valuable resource for investigating the molecular mechanisms of chitosan for the development of a greater vaccine.
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Quitosano , Nanopartículas , Vacunas , Humanos , Fosfatidilinositol 3-Quinasas , Adyuvantes InmunológicosRESUMEN
Fabry disease is an X-linked hereditary disorder caused by deficient α-galactosidase A (GLA) activity. Patients with Fabry disease are often treated with enzyme replacement therapy (ERT). However, ERT often induces the formation of neutralizing antidrug antibodies (ADAs), which may impair the therapeutic efficacy. Here, we report the case of a 32-year-old man with Fabry disease and resultant neutralizing ADAs who was treated by switching from agalsidase-α to agalsidase-ß. We monitored biomarkers, such as plasma globotriaosylsphingosine (lyso-Gb3), urinary globotriaosylceramide (Gb3), urinary mulberry bodies, renal and cardiac parameters, and disease severity during the treatment period. Although plasma lyso-Gb3 and urinary Gb3 levels quickly decreased within two months after the initiation of ERT with agalsidase-α, they gradually increased thereafter. The urinary mulberry bodies continued to appear. Both the ADA titer and serum mediated GLA inhibition rates started to increase after two months. Moreover, 3.5 years after ERT, the vacuolated podocyte area in the renal biopsy decreased slightly from 23.1 to 18.9%. However, plasma lyso-Gb3 levels increased, and urinary Gb3, mulberry body levels, and ADA titers remained high. Therefore, we switched to agalsidase-ß which reduced, but did not normalize, plasma lyso-Gb3 levels and stabilized renal and cardiac parameters. Disease severity was attenuated. However, urinary Gb3 and mulberry body levels did not decrease noticeably in the presence of high ADA titers. The kidneys take up a small amount of the administered recombinant enzyme, and the clearance of Gb3 that has accumulated in the kidney may be limited despite the switching from agalsidase-α to agalsidase-ß.
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Anticuerpos Neutralizantes , Biomarcadores , Terapia de Reemplazo Enzimático , Enfermedad de Fabry , Isoenzimas , Esfingolípidos , Trihexosilceramidas , alfa-Galactosidasa , Humanos , Enfermedad de Fabry/tratamiento farmacológico , Enfermedad de Fabry/diagnóstico , Masculino , Adulto , alfa-Galactosidasa/uso terapéutico , alfa-Galactosidasa/administración & dosificación , alfa-Galactosidasa/inmunología , Biomarcadores/sangre , Terapia de Reemplazo Enzimático/métodos , Isoenzimas/uso terapéutico , Isoenzimas/administración & dosificación , Anticuerpos Neutralizantes/sangre , Trihexosilceramidas/orina , Esfingolípidos/sangre , Glucolípidos , Riñón/patología , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Proteínas RecombinantesRESUMEN
Scanning of the mRNA transcript by the preinitiation complex (PIC) requires a panel of eukaryotic initiation factors, which includes eIF1 and eIF1A, the main transducers of stringent AUG selection. eIF1A plays an important role in start codon recognition; however, its molecular contacts with eIF5 are unknown. Using nuclear magnetic resonance, we unveil eIF1A's binding surface on the carboxyl-terminal domain of eIF5 (eIF5-CTD). We validated this interaction by observing that eIF1A does not bind to an eIF5-CTD mutant, altering the revealed eIF1A interaction site. We also found that the interaction between eIF1A and eIF5-CTD is conserved between humans and yeast. Using glutathione S-transferase pull-down assays of purified proteins, we showed that the N-terminal tail (NTT) of eIF1A mediates the interaction with eIF5-CTD and eIF1. Genetic evidence indicates that overexpressing eIF1 or eIF5 suppresses the slow growth phenotype of eIF1A-NTT mutants. These results suggest that the eIF1A-eIF5-CTD interaction during scanning PICs contributes to the maintenance of eIF1 within the open PIC.
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Factor 1 Eucariótico de Iniciación/metabolismo , Factores de Iniciación de Péptidos/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Secuencia de Aminoácidos , Factor 1 Eucariótico de Iniciación/química , Factor 1 Eucariótico de Iniciación/genética , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Factores de Iniciación de Péptidos/química , Factores de Iniciación de Péptidos/genética , Unión Proteica , Biosíntesis de Proteínas , Multimerización de Proteína , Estructura Terciaria de Proteína , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/genética , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Alineación de Secuencia , Factor 5A Eucariótico de Iniciación de TraducciónRESUMEN
The translation factor eIF5 is an important partner of eIF2, directly modulating its function in several critical steps. First, eIF5 binds eIF2/GTP/Met-tRNA(i)(Met) ternary complex (TC), promoting its recruitment to 40S ribosomal subunits. Secondly, its GTPase activating function promotes eIF2 dissociation for ribosomal subunit joining. Finally, eIF5 GDP dissociation inhibition (GDI) activity can antagonize eIF2 reactivation by competing with the eIF2 guanine exchange factor (GEF), eIF2B. The C-terminal domain (CTD) of eIF5, a W2-type HEAT domain, mediates its interaction with eIF2. Here, we characterize a related human protein containing MA3- and W2-type HEAT domains, previously termed BZW2 and renamed here as eIF5-mimic protein 1 (5MP1). Human 5MP1 interacts with eIF2 and eIF3 and inhibits general and gene-specific translation in mammalian systems. We further test whether 5MP1 is a mimic or competitor of the GEF catalytic subunit eIF2Bε or eIF5, using yeast as a model. Our results suggest that 5MP1 interacts with yeast eIF2 and promotes TC formation, but inhibits TC binding to the ribosome. Moreover, 5MP1 is not a GEF but a weak GDI for yeast eIF2. We propose that 5MP1 is a partial mimic and competitor of eIF5, interfering with the key steps by which eIF5 regulates eIF2 function.