RESUMEN
Cobalamin (vitamin B12) is important in gastrulation, nervous system development and haemoglobin formation. Mutations of the ABCD4 or LMBRD1 genes can lead to cobalamin-related disorders. We report a patient with disseminated skin hyperpigmentation caused by a homozygous LMBRD1 variant. Genetic disorders of cobalamin metabolism caused by variants in the ABCD4 or LMBRD1 genes should be considered in patients presenting with cutaneous hyperpigmentation. Click https://www.wileyhealthlearning.com/#/online-courses/a6ef1275-8325-4834-89d2-aa18fa31e63f for the corresponding questions to this CME article.
Asunto(s)
Hiperpigmentación , Deficiencia de Vitamina B 12 , Transportadoras de Casetes de Unión a ATP/genética , Femenino , Homocigoto , Humanos , Hiperpigmentación/genética , Mutación , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Vitamina B 12/uso terapéutico , Deficiencia de Vitamina B 12/complicacionesRESUMEN
Vitamin D3 (VD3) deficiency has been associated with increased risk for cirrhosis and hepatocellular carcinoma, a highly incident malignant neoplasia worldwide. On the other hand, VD3 supplementation has shown some beneficial effects in clinical studies and rodent models of chronic liver disease. However, preventive effects of dietary VD3 supplementation in cirrhosis-associated hepatocarcinogenesis is still unknow. To investigate this purpose, male Wistar rats submitted to a combined diethylnitrosamine- and thioacetamide-induced model were concomitantly supplemented with VD3 (5,000 and 10,000 IU/kg diet) for 25 weeks. Liver samples were collected for histological, biochemical and molecular analysis. Serum samples were used to measure 25-hydroxyvitamin D [25(OH)D] and alanine aminotransferase levels. Both VD3 interventions decreased hepatic collagen deposition and pro-inflammatory p65 protein levels, while increased hepatic antioxidant catalase and glutathione peroxidase activities and serum 25(OH)D, without a clear dose-response effect. Nonetheless, only the highest concentration of VD3 increased hepatic protein levels of VD receptor, while decreased the number of large preneoplastic glutathione-S-transferase- (>0.5 mm²) and keratin 8/18-positive lesions, as well the multiplicity of hepatocellular adenomas. Moreover, this intervention increased hepatic antioxidant Nrf2 protein levels and glutathione-S-transferase activity. In summary, dietary VD3 supplementation - in special the highest intervention - showed antifibrotic and antineoplastic properties in chemically-induced cirrhosis-associated hepatocarcinogenesis. The positive modulation of Nrf2 antioxidant axis may be mechanistically involved with these beneficial effects, and may guide future clinical studies.
Asunto(s)
Adenoma de Células Hepáticas/prevención & control , Carcinoma Hepatocelular/prevención & control , Suplementos Dietéticos , Cirrosis Hepática/tratamiento farmacológico , Neoplasias Hepáticas/prevención & control , Vitamina D/administración & dosificación , Adenoma de Células Hepáticas/inducido químicamente , Adenoma de Células Hepáticas/metabolismo , Adenoma de Células Hepáticas/patología , Alanina Transaminasa/sangre , Alanina Transaminasa/genética , Animales , Carcinoma Hepatocelular/inducido químicamente , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Catalasa/sangre , Catalasa/genética , Quimioprevención/métodos , Colágeno/genética , Colágeno/metabolismo , Dietilnitrosamina/toxicidad , Regulación de la Expresión Génica/efectos de los fármacos , Glutatión Peroxidasa/sangre , Glutatión Peroxidasa/genética , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Queratinas/genética , Queratinas/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Cirrosis Hepática/inducido químicamente , Cirrosis Hepática/metabolismo , Cirrosis Hepática/patología , Neoplasias Hepáticas/inducido químicamente , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Masculino , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Ratas , Ratas Wistar , Receptores de Calcitriol/genética , Receptores de Calcitriol/metabolismo , Tioacetamida/toxicidad , Vitamina D/análogos & derivados , Vitamina D/sangreRESUMEN
Ethylmalonic encephalopathy (EE) is a severe intoxication disorder caused by mutations in the ETHE1 gene that encodes a mitochondrial sulfur dioxygenase involved in the catabolism of hydrogen sulfide. It is biochemically characterized by tissue accumulation of hydrogen sulfide and its by-product thiosulfate, as well as of ethylmalonic acid due to hydrogen sulfide-induced inhibition of short-chain acyl-CoA dehydrogenase. Patients usually present with early onset severe brain damage associated to encephalopathy, chronic hemorrhagic diarrhea and vascular lesions with petechial purpura and orthostatic acrocyanosis whose pathophysiology is poorly known. Current treatment aims to reduce hydrogen sulfide accumulation, but does not significantly prevent encephalopathy and most fatalities. In this review, we will summarize the present knowledge obtained from human and animal studies showing that disruption of mitochondrial and redox homeostasis may represent relevant pathomechanisms of tissue damage in EE. Mounting evidence show that hydrogen sulfide and ethylmalonic acid markedly disturb critical mitochondrial functions and induce oxidative stress. Novel therapeutic strategies using promising candidate drugs for this devastating disease are also discussed.
Asunto(s)
Lesiones Encefálicas , Púrpura , Animales , Encéfalo/metabolismo , Encefalopatías Metabólicas Innatas , Lesiones Encefálicas/metabolismo , Homeostasis , Humanos , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Oxidación-Reducción , Púrpura/genética , Púrpura/metabolismo , Púrpura/patologíaRESUMEN
Ethylmalonic encephalopathy protein 1 (ETHE1) and molybdenum cofactor (MoCo) deficiencies are hereditary disorders that affect the catabolism of sulfur-containing amino acids. ETHE1 deficiency is caused by mutations in the ETHE1 gene, while MoCo deficiency is due to mutations in one of three genes involved in MoCo biosynthesis (MOCS1, MOCS2 and GPHN). Patients with both disorders exhibit abnormalities of the mitochondrial respiratory chain, among other biochemical findings. However, the pathophysiology of the defects has not been elucidated. To characterize cellular derangements, mitochondrial bioenergetics, dynamics, endoplasmic reticulum (ER)-mitochondria communication, superoxide production and apoptosis were evaluated in fibroblasts from four patients with ETHE1 deficiency and one with MOCS1 deficiency. The effect of JP4-039, a promising mitochondrial-targeted antioxidant, was also tested on cells. Our data show that mitochondrial respiration was decreased in all patient cell lines. ATP depletion and increased mitochondrial mass was identified in the same cells, while variable alterations in mitochondrial fusion and fission were seen. High superoxide levels were found in all cells and were decreased by treatment with JP4-039, while the respiratory chain activity was increased by this antioxidant in cells in which it was impaired. The content of VDAC1 and IP3R, proteins involved in ER-mitochondria communication, was decreased, while DDIT3, a marker of ER stress, and apoptosis were increased in all cell lines. These data demonstrate that previously unrecognized broad disturbances of cellular function are involved in the pathophysiology of ETHE1 and MOCS1 deficiencies, and that reduction of mitochondrial superoxide by JP4-039 is a promising strategy for adjuvant therapy of these disorders.
Asunto(s)
Liasas de Carbono-Carbono/deficiencia , Retículo Endoplásmico/metabolismo , Metabolismo Energético , Fibroblastos/patología , Homeostasis , Mitocondrias/metabolismo , Dinámicas Mitocondriales , Proteínas Mitocondriales/deficiencia , Proteínas de Transporte Nucleocitoplasmático/deficiencia , Adenosina Trifosfato/biosíntesis , Apoptosis , Liasas de Carbono-Carbono/metabolismo , Línea Celular , Respiración de la Célula , Análisis Mutacional de ADN , Fibroblastos/metabolismo , Humanos , Proteínas Mitocondriales/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Oxidación-Reducción , Consumo de Oxígeno , Superóxidos/metabolismoRESUMEN
PURPOSE: To investigate whether ERK/MNK/eIF4E contributes chemoresistance in ovarian cancer. METHODS: The phosphorylated levels of Erk, Mnk, and eIF4E were systematically analyzed in ovarian cancer patients before and after chemotherapy, and ovarian cancer cells exposed to short- and long-term chemo-agent treatment. The roles of Erk/Mnk/eIF4E were investigated using pharmacological and genetic approaches. RESULTS: Increased phosphorylation levels of ERK, Mnk1, and eIF4E were observed in ovarian cancer cell exposed to chemotherapeutic agents, and paclitaxel-resistant SK-OV-3-r cells, and is a common response of ovarian cancer patients undergoing chemotherapy. MEK inhibitor U0126 inhibits basal and chemodrug-induced phosphorylation of ERK as well as Mnk1 and eIF4E, suggesting that Mnk1/eIF4E are the downstream signaling of ERK pathway and chemotherapy agents activate ERK/MNK/eIF4E in a MEK-dependent manner. eIF4E overexpression promotes ovarian cancer cell growth without affecting migration. In addition, ovarian cancer cells with eIF4E overexpression are more resistant to chemotherapeutic agents in aspect of growth inhibition and apoptosis induction compared to control cells. In contrast, eIF4E depletion augments chemotherapeutic agents' effect in ovarian cancer cells. These demonstrate that eIF4E play roles in growth and chemoresistance in ovarian cancer. MEK inhibitor U0126 also significantly enhances chemotherapeutic agents' inhibitory effects. CONCLUSIONS: Our work shows that ERK/Mnk/eIF4E activation is critically involved in ovarian cancer chemoresistance and inhibiting ERK/Mnk/eIF4E broadly sensitizes ovarian cancer response to chemotherapy.
Asunto(s)
ATPasas Transportadoras de Cobre/metabolismo , Resistencia a Antineoplásicos/fisiología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Neoplasias Ováricas/patología , Proteínas Serina-Treonina Quinasas/metabolismo , Antineoplásicos/farmacología , Resistencia a Antineoplásicos/efectos de los fármacos , Femenino , Humanos , Fosforilación/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
Therapeutics are currently unavailable for Venezuelan equine encephalitis virus (VEEV), which elicits flu-like symptoms and encephalitis in humans, with an estimated 14% of cases resulting in neurological disease. Here we identify anti-VEEV agents using in silico structure-based-drug-design (SBDD) for the first time, characterising inhibitors that block recognition of VEEV capsid protein (C) by the host importin (IMP) α/ß1 nuclear transport proteins. From an initial screen of 1.5 million compounds, followed by in silico refinement and screening for biological activity in vitro, we identified 21 hit compounds which inhibited IMPα/ß1:C binding with IC50s as low as 5 µM. Four compounds were found to inhibit nuclear import of C in transfected cells, with one able to reduce VEEV replication at µM concentration, concomitant with reduced C nuclear accumulation in infected cells. Further, this compound was inactive against a mutant VEEV that lacks high affinity IMPα/ß1:C interaction, supporting the mode of its antiviral action to be through inhibiting C nuclear localization. This successful application of SBDD paves the way for lead optimization for VEEV antivirals, and is an exciting prospect to identify inhibitors for the many other viral pathogens of significance that require IMPα/ß1 in their infectious cycle.
Asunto(s)
Proteínas de la Cápside/efectos de los fármacos , Descubrimiento de Drogas/métodos , Virus de la Encefalitis Equina Venezolana/efectos de los fármacos , Transporte Activo de Núcleo Celular/efectos de los fármacos , Animales , Antivirales/farmacología , Cápside , Proteínas de la Cápside/metabolismo , Núcleo Celular/metabolismo , Chlorocebus aethiops , Simulación por Computador , Diseño de Fármacos , Virus de la Encefalitis Equina Venezolana/patogenicidad , Humanos , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Células Vero , Replicación Viral/efectos de los fármacos , alfa Carioferinas/antagonistas & inhibidores , alfa Carioferinas/metabolismo , beta Carioferinas/antagonistas & inhibidores , beta Carioferinas/metabolismoRESUMEN
Venezuelan equine encephalitis virus (VEEV) is a New World alphavirus that is vectored by mosquitos and cycled in rodents. It can cause disease in equines and humans characterized by a febrile illness that may progress into encephalitis. Like the capsid protein of other viruses, VEEV capsid is an abundant structural protein that binds to the viral RNA and interacts with the membrane-bound glycoproteins. It also has protease activity, allowing cleavage of itself from the growing structural polypeptide during translation. However, VEEV capsid protein has additional nonstructural roles within the host cell functioning as the primary virulence factor for VEEV. VEEV capsid inhibits host transcription and blocks nuclear import in mammalian cells, at least partially due to its complexing with the host CRM1 and importin α/ß1 nuclear transport proteins. VEEV capsid also shuttles between the nucleus and cytoplasm and is susceptible to inhibitors of nuclear trafficking, making it a promising antiviral target. Herein, the role of VEEV capsid in viral replication and pathogenesis will be discussed including a comparison to proteins of other alphaviruses.
Asunto(s)
Proteínas de la Cápside/metabolismo , Cápside/metabolismo , Virus de la Encefalitis Equina Venezolana/patogenicidad , ARN Viral/metabolismo , Replicación Viral , Transporte Activo de Núcleo Celular , Animales , Cápside/química , Proteínas de la Cápside/genética , Línea Celular , Virus de la Encefalitis Equina del Este , Virus de la Encefalitis Equina Venezolana/genética , Virus de la Encefalitis Equina Venezolana/metabolismo , Virus de la Encefalitis Equina del Oeste , Caballos , Humanos , Carioferinas/genética , Carioferinas/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Factores de Virulencia , Replicación Viral/genética , Proteína Exportina 1RESUMEN
In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.
Asunto(s)
Regiones no Traducidas 5' , Virus del Tumor Mamario del Ratón/genética , Iniciación de la Cadena Peptídica Traduccional , ARN Viral/química , Animales , Línea Celular , Humanos , Luciferasas de Luciérnaga/análisis , Luciferasas de Luciérnaga/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Oocitos/metabolismo , Plásmidos/genética , Regiones Promotoras Genéticas , Caperuzas de ARN/antagonistas & inhibidores , ARN Mensajero/química , Conejos , Xenopus laevis , Productos del Gen rev del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
mRNA stability is modulated by elements in the mRNA transcript and their cognate RNA binding proteins. Poly(U) binding protein 1 (Pub1) is a cytoplasmic Saccharomyces cerevisiae mRNA binding protein that stabilizes transcripts containing AU-rich elements (AREs) or stabilizer elements (STEs). In a yeast two-hybrid screen, we identified nuclear poly(A) binding protein 2 (Nab2) as being a Pub1-interacting protein. Nab2 is an essential nucleocytoplasmic shuttling mRNA binding protein that regulates poly(A) tail length and mRNA export. The interaction between Pub1 and Nab2 was confirmed by copurification and in vitro binding assays. The interaction is mediated by the Nab2 zinc finger domain. Analysis of the functional link between these proteins reveals that Nab2, like Pub1, can modulate the stability of specific mRNA transcripts. The half-life of the RPS16B transcript, an ARE-like sequence-containing Pub1 target, is decreased in both nab2-1 and nab2-67 mutants. In contrast, GCN4, an STE-containing Pub1 target, is not affected. Similar results were obtained for other ARE- and STE-containing Pub1 target transcripts. Further analysis reveals that the ARE-like sequence is necessary for Nab2-mediated transcript stabilization. These results suggest that Nab2 functions together with Pub1 to modulate mRNA stability and strengthen a model where nuclear events are coupled to the control of mRNA turnover in the cytoplasm.
Asunto(s)
Proteínas de Transporte Nucleocitoplasmático/metabolismo , Proteínas de Unión a Poli(A)/metabolismo , Estabilidad del ARN , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Hibridación Fluorescente in Situ , Proteínas de Transporte Nucleocitoplasmático/química , Proteínas de Transporte Nucleocitoplasmático/aislamiento & purificación , Proteínas de Unión a Poli(A)/aislamiento & purificación , Unión Proteica , Estructura Terciaria de Proteína , ARN de Hongos/metabolismo , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/aislamiento & purificación , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/aislamiento & purificación , Técnicas del Sistema de Dos HíbridosRESUMEN
Phytochrome A signaling shows two photobiologically discrete outputs: so-called very-low-fluence responses (VLFR) and high-irradiance responses (HIR). By modifying previous screening protocols, we isolated two Arabidopsis mutants retaining VLFR and lacking HIR. Phytochrome A negatively or positively regulates phytochrome B signaling, depending on light conditions. These mutants retained the negative but lacked the positive regulation. Both mutants carry the novel phyA-302 allele, in which Glu-777 (a residue conserved in angiosperm phytochromes) changed to Lys in the PAS2 motif of the C-terminal domain. The phyA-302 mutants showed a 50% reduction in phytochrome A levels in darkness, but this difference was compensated for by greater stability under continuous far-red light. phyA-302:green fluorescent protein fusion proteins showed normal translocation from the cytosol to the nucleus under continuous far-red light but failed to produce nuclear spots, suggesting that nuclear speckles could be involved in HIR signaling and phytochrome A degradation. We propose that the PAS2 domain of phytochrome A is necessary to initiate signaling in HIR but not in VLFR, likely via interaction with a specific partner.