RESUMEN
As chronic inflammation is a hallmark of obesity, pathways that integrate nutrient- and pathogen sensing pathways are of great interest in understanding the mechanisms of insulin resistance, type 2 diabetes, and other chronic metabolic pathologies. Here, we provide evidence that double-stranded RNA-dependent protein kinase (PKR) can respond to nutrient signals as well as endoplasmic reticulum (ER) stress and coordinate the activity of other critical inflammatory kinases such as the c-Jun N-terminal kinase (JNK) to regulate insulin action and metabolism. PKR also directly targets and modifies insulin receptor substrate and hence integrates nutrients and insulin action with a defined pathogen response system. Dietary and genetic obesity features marked activation of PKR in adipose and liver tissues and absence of PKR alleviates metabolic deterioration due to nutrient or energy excess in mice. These findings demonstrate PKR as a critical component of an inflammatory complex that responds to nutrients and organelle dysfunction.
Asunto(s)
Enfermedades Metabólicas/metabolismo , eIF-2 Quinasa/metabolismo , Animales , Femenino , Humanos , Proteínas Sustrato del Receptor de Insulina/metabolismo , MAP Quinasa Quinasa 4/metabolismo , Masculino , Ratones , eIF-2 Quinasa/genéticaRESUMEN
A 62-year-old man visited the Department of Otorhinolaryngology at our hospital with a chief complaint of a pharyngeal mass. He was admitted to our department with a diagnosis of T-cell lymphoma based on a biopsy of a mesopharyngeal tumor. Although clonality analysis was not performed due to the lack of an appropriate sample, we considered the possibility of lymphoma-type (Lugano classification stage II) adult T-cell leukemia-lymphoma (ATL), as the anti-HTLV-1 antibody was positive. During the course of the disease, the peripheral blood smear revealed atypical lymphocytes with cleaved nuclei, and inverse PCR was performed with DNA extracted from those cells; however, the result showed that the pattern of HTLV-1 proviral DNA integration sites was polyclonal. Further, we performed RNA in situ hybridization targeting HTLV-1 bZIP factor (HBZ-ISH) using the formalin-fixed paraffin-embedded (FFPE) tissue samples of the mesopharyngeal tumor, and a high expression of HBZ was found in the tumor cells, leading to the diagnosis of ATL. These findings suggest the effectiveness of the novel diagnostic method using FFPE tissue samples for ATL.
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Virus Linfotrópico T Tipo 1 Humano , Leucemia-Linfoma de Células T del Adulto , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Virus Linfotrópico T Tipo 1 Humano/genética , Humanos , Hibridación in Situ , Leucemia-Linfoma de Células T del Adulto/diagnóstico , Masculino , ARNRESUMEN
The inflammasome regulates the release of caspase activation-dependent cytokines, including interleukin (IL)-1ß, IL-18 and high-mobility group box 1 (HMGB1). By studying HMGB1 release mechanisms, here we identify a role for double-stranded RNA-dependent protein kinase (PKR, also known as EIF2AK2) in inflammasome activation. Exposure of macrophages to inflammasome agonists induced PKR autophosphorylation. PKR inactivation by genetic deletion or pharmacological inhibition severely impaired inflammasome activation in response to double-stranded RNA, ATP, monosodium urate, adjuvant aluminium, rotenone, live Escherichia coli, anthrax lethal toxin, DNA transfection and Salmonella typhimurium infection. PKR deficiency significantly inhibited the secretion of IL-1ß, IL-18 and HMGB1 in E. coli-induced peritonitis. PKR physically interacts with several inflammasome components, including NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3), NLRP1, NLR family CARD domain-containing protein 4 (NLRC4), absent in melanoma 2 (AIM2), and broadly regulates inflammasome activation. PKR autophosphorylation in a cell-free system with recombinant NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC, also known as PYCARD) and pro-caspase-1 reconstitutes inflammasome activity. These results show a crucial role for PKR in inflammasome activation, and indicate that it should be possible to pharmacologically target this molecule to treat inflammation.
Asunto(s)
Proteína HMGB1/metabolismo , Inflamasomas/metabolismo , eIF-2 Quinasa/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Adenosina Trifosfato/farmacología , Animales , Antígenos Bacterianos/farmacología , Proteínas Reguladoras de la Apoptosis/metabolismo , Toxinas Bacterianas/farmacología , Proteínas Adaptadoras de Señalización CARD/metabolismo , Proteínas de Unión al Calcio/metabolismo , Proteínas Portadoras/metabolismo , Línea Celular , Células Cultivadas , Cristalinas/metabolismo , Escherichia coli/inmunología , Escherichia coli/fisiología , Infecciones por Escherichia coli/inmunología , Infecciones por Escherichia coli/metabolismo , Femenino , Proteína HMGB1/sangre , Humanos , Inflamasomas/agonistas , Interleucina-18/sangre , Interleucina-1beta/sangre , Interleucina-6/análisis , Interleucina-6/sangre , Macrófagos Peritoneales/efectos de los fármacos , Macrófagos Peritoneales/metabolismo , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Proteína con Dominio Pirina 3 de la Familia NLR , Proteínas NLR , Peritonitis/metabolismo , Fosforilación , ARN Bicatenario/inmunología , ARN Bicatenario/farmacología , Rotenona/farmacología , Infecciones por Salmonella/inmunología , Infecciones por Salmonella/metabolismo , Salmonella typhimurium/inmunología , Salmonella typhimurium/fisiología , Transfección , Ácido Úrico/farmacología , eIF-2 Quinasa/antagonistas & inhibidores , eIF-2 Quinasa/deficiencia , eIF-2 Quinasa/genéticaRESUMEN
Protein kinase RNA-activated (PKR) has long been known to be activated by viral double-stranded RNA (dsRNA) as part of the mammalian immune response. However, in mice PKR is also activated by metabolic stress in the absence of viral infection, and this requires a functional kinase domain, as well as a functional dsRNA-binding domain. The endogenous cellular RNA that potentially leads to PKR activation during metabolic stress is unknown. We investigated this question using mouse embryonic fibroblast cells expressing wild-type PKR (PKRWT) or PKR with a point mutation in each dsRNA-binding motif (PKRRM). Using this system, we identified endogenous RNA that interacts with PKR after induction of metabolic stress by palmitic acid (PA) treatment. Specifically, RIP-Seq analyses showed that the majority of enriched RNAs that interacted with WT PKR (≥twofold, false discovery rate ≤ 5%) were small nucleolar RNAs (snoRNAs). Immunoprecipitation of PKR in extracts of UV-cross-linked cells, followed by RT-qPCR, confirmed that snoRNAs were enriched in PKRWT samples after PA treatment, but not in the PKRRM samples. We also demonstrated that a subset of identified snoRNAs bind and activate PKR in vitro; the presence of a 5'-triphosphate enhanced PKR activity compared with the activity with a 5'-monophosphate, for some, but not all, snoRNAs. Finally, we demonstrated PKR activation in cells upon snoRNA transfection, supporting our hypothesis that endogenous snoRNAs can activate PKR. Our results suggest an unprecedented and unexpected model whereby snoRNAs play a role in the activation of PKR under metabolic stress.
Asunto(s)
ARN Nucleolar Pequeño/metabolismo , Estrés Fisiológico , eIF-2 Quinasa/metabolismo , Animales , Células CHO , Extractos Celulares , Cricetinae , Cricetulus , Activación Enzimática/efectos de los fármacos , Inmunoprecipitación , Ratones , Ácido Palmítico/farmacología , Reproducibilidad de los Resultados , Estrés Fisiológico/efectos de los fármacosRESUMEN
Obesity is a life-threatening factor and is often associated with dysregulation of gene expression. Here, we show that the CNOT3 subunit of the CCR4-NOT deadenylase complex is critical to metabolic regulation. Cnot3(+/-) mice are lean with hepatic and adipose tissues containing reduced levels of lipids, and show increased metabolic rates and enhanced glucose tolerance. Cnot3(+/-) mice remain lean and sensitive to insulin even on a high-fat diet. Furthermore, introduction of Cnot3 haplodeficiency in ob/ob mice ameliorated the obese phenotype. Hepatic expression of most mRNAs is not altered in Cnot3(+/-) vis-à-vis wild-type mice. However, the levels of specific mRNAs, such as those coding for energy metabolism-related PDK4 and IGFBP1, are increased in Cnot3(+/-) hepatocytes, having poly(A) tails that are longer than those seen in control cells. We provide evidence that CNOT3 is involved in recruitment of the CCR4-NOT deadenylase to the 3' end of specific mRNAs. Finally, as CNOT3 levels in the liver and white adipose tissues decrease upon fasting, we propose that CNOT3 responds to feeding conditions to regulate deadenylation-specific mRNAs and energy metabolism.
Asunto(s)
Metabolismo Energético , Obesidad/genética , ARN Mensajero/biosíntesis , Factores de Transcripción/metabolismo , Tejido Adiposo/metabolismo , Animales , Dieta , Insulina/metabolismo , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/biosíntesis , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Hígado/metabolismo , Ratones , Ratones Obesos/genética , Ratones Obesos/metabolismo , Ratones Transgénicos , Datos de Secuencia Molecular , Obesidad/metabolismo , Proteínas Serina-Treonina Quinasas/biosíntesis , Proteínas Serina-Treonina Quinasas/genética , Piruvato Deshidrogenasa Quinasa Acetil-Transferidora , ARN Mensajero/genética , Factores de Transcripción/genéticaRESUMEN
Extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is a rare subtype of non-Hodgkin lymphoma (NHL) with poor prognosis, particularly in relapsed or refractory patients. Thus, timely detection of relapse and appropriate disease management are crucial. We present two patients with ENKTL, wherein positron emission tomography-computed tomography (PET-CT) with total-body coverage after induction therapy, detected newly relapsed regions in the bone marrow of the lower leg prior to progression. Case 1: A 47-year-old woman with nasal obstruction, showing 18F-fluoro-deoxyglucose (FDG) uptake in the nasal cavity (Lugano stage IE). After induction therapy (RT-2/3 DeVIC), PET-CT revealed abnormal uptake only in the right fibula. Case 2: A 68-year-old man with a skin nodule/ulcer and an enlarged right inguinal lymph node was diagnosed with advanced ENKTL. A PET-CT scan revealed abnormal uptake in the subcutaneous mass of the right medial thigh, lymph nodes, and descending colon (Lugano stage IV). After induction therapy, PET-CT revealed new abnormal uptake only in the left tibia. In both patients, CT-guided biopsy confirmed ENKTL recurrence. Moreover, PET-CT with whole-body coverage was useful for the timely assessment of relapse and detection of asymptomatic bone involvement. This approach allowed for modifications to treatment strategies in certain patients.
Asunto(s)
Linfoma Extranodal de Células NK-T , Tomografía Computarizada por Tomografía de Emisión de Positrones , Masculino , Femenino , Humanos , Persona de Mediana Edad , Anciano , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Médula Ósea/patología , Tomografía de Emisión de Positrones/métodos , Pierna/patología , Linfoma Extranodal de Células NK-T/patología , Fluorodesoxiglucosa F18 , Radiofármacos , Recurrencia Local de NeoplasiaRESUMEN
OBJECTIVE: Weight loss following vertical sleeve gastrectomy (VSG) in youth can range from 10% to 50%. We examined whether there are differences in demographic or metabolic parameters before VSG in youth who achieve above-average weight loss (AAWL) versus below-average weight loss (BAWL) at 1 year post VSG and if youth with BAWL still achieve metabolic health improvements at 1 year post VSG. METHODS: Demographic, anthropometric, and clinical lab data were collected before VSG and at 1, 3, 6, and 12 months after VSG. RESULTS: Forty-three youth with a mean age of 16.9 (SD 1.7) years before VSG were studied; 70% were female, 19% non-Hispanic Black, 58% non-Hispanic White, and 23% mixed/other race. Mean baseline BMI was 51.1 (SD 10.5) kg/m2. Average weight loss was 25.8%. The AAWL group lost 18.6 kg/m2 (35.3%) versus the BAWL group, who lost 8.8 kg/m2 (17.5%). BMI, age, race, sex, and socioeconomic status at baseline were similar between AAWL and BAWL groups; however, the BAWL group had a higher frequency of pre-VSG dysglycemia, steatotic liver disease, and dyslipidemia. At 1 year post VSG, fewer youth in the BAWL group achieved ideal health parameters, and they had less resolution of comorbidities. CONCLUSIONS: The presence of comorbidities before VSG is associated with less weight loss and reduced resolution of metabolic conditions at 1 year post VSG.
Asunto(s)
Índice de Masa Corporal , Gastrectomía , Pérdida de Peso , Humanos , Femenino , Masculino , Adolescente , Gastrectomía/métodos , Gastrectomía/efectos adversos , Resultado del Tratamiento , Obesidad Mórbida/cirugía , Obesidad Infantil/cirugía , Dislipidemias/epidemiología , Cirugía Bariátrica/métodos , Periodo PreoperatorioRESUMEN
Mitochondrial fatty acid oxidation (FAO) is essential for hematopoietic stem cell (HSC) self-renewal; however, the mechanism by which mitochondrial metabolism controls HSC fate remains unknown. Here, we show that within the hematopoietic lineage, HSCs have the largest mitochondrial NADPH pools, which are required for proper HSC cell fate and homeostasis. Bioinformatic analysis of the HSC transcriptome, biochemical assays, and genetic inactivation of FAO all indicate that FAO-generated NADPH fuels cholesterol synthesis in HSCs. Interference with FAO disturbs the segregation of mitochondrial NADPH toward corresponding daughter cells upon single HSC division. Importantly, we have found that the FAO-NADPH-cholesterol axis drives extracellular vesicle (EV) biogenesis and release in HSCs, while inhibition of EV signaling impairs HSC self-renewal. These data reveal the existence of a mitochondrial NADPH-cholesterol axis for EV biogenesis that is required for hematopoietic homeostasis and highlight the non-stochastic nature of HSC fate determination.
Asunto(s)
Vesículas Extracelulares , Células Madre Hematopoyéticas , NADP/metabolismo , Células Madre Hematopoyéticas/metabolismo , Diferenciación Celular/fisiología , Autorrenovación de las CélulasRESUMEN
Spermatogenesis is a complex process that involves cooperation of germ cells and testicular somatic cells. Various genetic disorders lead to impaired spermatogenesis, defective sperm function and male infertility. Here we show that Cnot7(-/-) males are sterile owing to oligo-astheno-teratozoospermia, suggesting that Cnot7, a CCR4-associated transcriptional cofactor, is essential for spermatogenesis. Maturation of spermatids is unsynchronized and impaired in seminiferous tubules of Cnot7(-/-) mice. Transplantation of spermatogonial stem cells from male Cnot7(-/-) mice to seminiferous tubules of Kit mutant mice (Kit(W/W-v)) restores spermatogenesis, suggesting that the function of testicular somatic cells is damaged in the Cnot7(-/-) condition. The testicular phenotypes of Cnot7(-/-) mice are similar to those of mice deficient in retinoid X receptor beta (Rxrb). We further show that Cnot7 binds the AF-1 domain of Rxrb and that Rxrb malfunctions in the absence of Cnot7. Therefore, Cnot7 seems to function as a coregulator of Rxrb in testicular somatic cells and is thus involved in spermatogenesis.
Asunto(s)
Proteínas Cromosómicas no Histona/fisiología , Proteínas de Unión al ADN/fisiología , Regulación de la Expresión Génica , Oligospermia/complicaciones , Motilidad Espermática , Espermatozoides/anomalías , Animales , Células COS , Factor 1 de Ensamblaje de la Cromatina , Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Femenino , Fibroblastos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Desnudos , Oligospermia/etiología , Oligospermia/genética , Fenotipo , Proteínas Proto-Oncogénicas c-kit/genética , Proteínas Proto-Oncogénicas c-kit/fisiología , Túbulos Seminíferos/metabolismo , Espermatogénesis/genética , Trasplante de Células MadreRESUMEN
Coagulation factor X (FX) deficiency causes severe hemorrhagic symptoms. We herein report a 90-year-old man with hemorrhagic symptoms and prolongation of prothrombin time (PT) and activated partial thromboplastin time (APTT). Cross-mixing tests showed a factor deficiency pattern, but administration of plasma products was not effective. Acquired coagulation factor deficiency was suspected, and immunosuppressive therapy was started. After the intervention, his hemorrhagic symptoms improved. A decrease in FX activity was later confirmed, and anti-FX autoantibody was retrospectively detected by an enzyme-linked immunosorbent assay. Immediate intervention is important for patients suspected of having acquired coagulation factor deficiency.
Asunto(s)
Deficiencia del Factor X , Masculino , Humanos , Anciano de 80 o más Años , Deficiencia del Factor X/tratamiento farmacológico , Estudios Retrospectivos , Corticoesteroides , Autoanticuerpos , Factores de Coagulación SanguíneaRESUMEN
Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent hepatic disorders that 20-30% of the world population suffers from. The feature of NAFLD is excess lipid accumulation in the liver, exacerbating multiple metabolic syndromes such as hyperlipidemia, hypercholesterolemia, hypertension, and type 2 diabetes. Approximately 20-30% of NAFLD cases progress to more severe chronic hepatitis, known as non-alcoholic steatohepatitis (NASH), showing deterioration of hepatic functions and liver fibrosis followed by cirrhosis and cancer. Previous studies uncovered that several metabolic regulators had roles in disease progression as key factors. Peroxisome proliferator-activated receptor alpha (PPARα) has been identified as one of the main players in hepatic lipid homeostasis. PPARα is abundantly expressed in hepatocytes, and is a ligand-dependent nuclear receptor belonging to the NR1C nuclear receptor subfamily, orchestrating lipid/glucose metabolism, inflammation, cell proliferation, and carcinogenesis. PPARα agonists are expected to be novel prescription drugs for NASH treatment, and some of them (e.g., Lanifibranor) are currently under clinical trials. These potential novel drugs are developed based on the knowledge of PPARα-activating target genes related to NAFLD and NASH. Intriguingly, PPARα is known to suppress the expression of subsets of target genes under agonist treatment; however, the mechanisms of PPARα-mediated gene suppression and functions of these genes are not well understood. In this review, we summarize and discuss the mechanisms of target gene repression by PPARα and the roles of repressed target genes on hepatic lipid metabolism, fibrosis and carcinogenesis related to NALFD and NASH, and provide future perspectives for PPARα pharmaceutical potentials.
RESUMEN
Extracellular vesicles (EVs) have gained considerable attention as vital circulating biomarkers since their structure and composition resemble the originating cells. The investigation of EVs' biochemical and biophysical properties is of great importance to map them to their parental cells and to better understand their functionalities. In this study, a novel frequency-dependent impedance measurement system has been developed to characterize EVs based on their unique dielectric properties. The system is composed of an insulator-based dielectrophoretic (iDEP) device to entrap and immobilize a cluster of vesicles followed by utilizing electrical impedance spectroscopy (EIS) to measure their impedance at a wide frequency spectrum, aiming to analyze both their membrane and cytosolic charge-dependent contents. The EIS was initially utilized to detect nano-size vesicles with different biochemical compositions, including liposomes synthesized with different lipid compositions, as well as EVs and lipoproteins with similar biophysical properties but dissimilar biochemical properties. Moreover, EVs derived from the same parental cells but treated with different culture conditions were characterized to investigate the correlation of impedance changes with biochemical properties and functionality in terms of pro-inflammatory responses. The system also showed the ability to discriminate between EVs derived from different cellular origins as well as among size-sorted EVs harbored from the same cellular origin. This proof-of-concept approach is the first step towards utilizing EIS as a label-free, non-invasive, and rapid sensor for detection and characterization of pathogenic EVs and other nanovesicles in the future.
Asunto(s)
Espectroscopía Dieléctrica , Vesículas Extracelulares , Impedancia EléctricaRESUMEN
A variety of stem cells are controlled by the actions of multiple growth factors in vitro. However, it remains largely unclear how growth factors control the proliferation and differentiation of stem cells in vivo. Here, we describe a novel paracrine mechanism for regulating a stem cell niche in early mammalian embryos, which involves communication between the inner cell mass (ICM) and the trophectoderm, from which embryonic stem (ES) cells and trophoblast stem (TS) cells can be derived, respectively. It is known that ES cells produce fibroblast growth factor (FGF)4 and that TS cells produce bone morphogenetic protein (Bmp)4. We provide evidence that FRS2alpha mediates activation of the extracellular signal-regulated progein kinase (ERK) pathway to enhance expression of transcription factor Cdx2 in TS cells in response to FGF4. Cdx2 in turn binds to an FGF4-responsive enhancer element of the promoter region of Bmp4, leading to production and secretion of Bmp4. Moreover, exogenous Bmp4 is able to rescue the defective growth of Frs2alpha-null ICM. These findings suggest an important role of Cdx2 for production of Bmp4 in TS cells to promote the proper growth of early mouse embryos.
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Masa Celular Interna del Blastocisto/metabolismo , Proteína Morfogenética Ósea 4/metabolismo , Diferenciación Celular , Proliferación Celular , Células Madre Embrionarias/metabolismo , Factor 4 de Crecimiento de Fibroblastos/metabolismo , Proteínas de Homeodominio/metabolismo , Proteínas de la Membrana/metabolismo , Factores de Transcripción/metabolismo , Trofoblastos/metabolismo , Región de Flanqueo 5' , Animales , Sitios de Unión , Masa Celular Interna del Blastocisto/citología , Masa Celular Interna del Blastocisto/efectos de los fármacos , Proteína Morfogenética Ósea 4/genética , Factor de Transcripción CDX2 , Proteínas Portadoras/metabolismo , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Células Madre Embrionarias/efectos de los fármacos , Elementos de Facilitación Genéticos , Activación Enzimática , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Regulación del Desarrollo de la Expresión Génica , Intrones , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Comunicación Paracrina , Inhibidores de Proteínas Quinasas/farmacología , Interferencia de ARN , ARN Mensajero/metabolismo , Proteínas Recombinantes/metabolismo , Transducción de Señal , Factores de Tiempo , Transfección , Trofoblastos/efectos de los fármacosRESUMEN
BACKGROUND: Oxaliplatin is one of the key drugs for the treatment of colorectal cancer, although it is known to cause hepatic sinusoidal injury. METHOD: Thirty-one patients underwent modified FOLFOX6 therapy from April 2006 and December 2009 at our hospital. Four patients were excluded from this study because they had too many intervals in their therapeutic courses. The size of the spleen and the blood platelet count were analyzed before and after 6 months of FOLFOX therapy. The spleen was measured using CT scan, and the splenic index(SI=length×width×height)was evaluated. RESULTS: After 6 months of treatment, the mean SI was increased from 229 cm3 to 323 cm3(p<0. 01). At the same time, the mean platelet count was decreased from 26. 9 ×10 / / 4 mm3 to 17. 1×104 mm3(p<0. 01). A negative correlation was found between the ratio of SI and the platelet count after 6 months of treatment to baseline(r=-0. 42, p=0. 030). SI increased by>50% in 12 patients (44. 4%). The platelet count decreased more severely in patients whose SI increased by>50%(p=0. 028). CONCLUSIONS: Splenomegaly and thrombocytopenia were observed in patients who underwent FOLFOX therapy. These are candidate parameters for evaluating hepatic sinusoidal injury.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Esplenomegalia/inducido químicamente , Anciano , Femenino , Fluorouracilo/efectos adversos , Humanos , Leucovorina/efectos adversos , Masculino , Compuestos Organoplatinos/efectos adversos , Recuento de PlaquetasRESUMEN
Argonaute 2 (Ago2) is the main component of the RNA-induced silencing complex. We recently showed that liver-specific Ago2-deficiency in mice (L-Ago2 knockout [KO] mice) enhances mitochondrial oxidation and alleviates obesity-associated pathophysiology. However, the precise mechanisms behind the role of hepatic Ago2 in regulating the mitochondrial oxidation associated with glucose metabolism are still unclear. Here, we show that hepatic Ago2 regulates the function of peroxisome proliferator-activated receptor α (PPARα) for oxidative metabolism. In both genetically and diet-induced severe obese conditions, L-Ago2 KO mice developed obesity and hepatic steatosis but exhibited improved glucose metabolism accompanied by lowered expression levels of pathologic microRNAs (miRNAs), including miR-802, miR-103/107, and miR-152, and enhanced expression of PPARα and its target genes regulating oxidative metabolism in the liver. We then investigated the role of hepatic Ago2 in the outcomes of vertical sleeve gastrectomy (VSG) in which PPARα plays a crucial role in a drastic transcription reprogram associated with improved glycemia post VSG. Whereas VSG reduced body weight and improved fatty liver in wild-type mice, these effects were not observed in hepatic Ago2-deficient mice. Conversely, glucose metabolism was improved in a hepatic Ago2-dependent manner post VSG. Treating Ago2-deficient primary hepatocytes with WY-14643, a PPARα agonist, showed that Ago2-deficiency enhances sensitivity to WY-14643 and increases expression of PPARα target genes and mitochondrial oxidation. Our findings suggest that hepatic Ago2 function is intrinsically associated with PPARα that links Ago2-mediated RNA silencing with mitochondrial functions for oxidation and obesity-associated pathophysiology.
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Proteínas Argonautas/deficiencia , Hígado/metabolismo , Obesidad/metabolismo , Obesidad/cirugía , PPAR alfa/metabolismo , Animales , Proteínas Argonautas/genética , Cirugía Bariátrica , Glucosa/metabolismo , Prueba de Tolerancia a la Glucosa , Control Glucémico , Hepatocitos/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/tratamiento farmacológico , Obesidad/genética , Estrés Oxidativo , PPAR alfa/genética , Pirimidinas/administración & dosificaciónRESUMEN
The bile salt export pump (BSEP) is responsible for the export of bile acid from hepatocytes. Impaired transcellular transport of bile acids in hepatocytes with mutations in BSEP causes cholestasis. Compensatory mechanisms to regulate the intracellular bile acid concentration in human hepatocytes with BSEP deficiency remain unclear. To define pathways that prevent cytotoxic accumulation of bile acid in hepatocytes, we developed a human induced pluripotent stem cell-based model of isogenic BSEP-deficient hepatocytes in a Transwell culture system. Induced hepatocytes (i-Heps) exhibited defects in the apical export of bile acids but maintained a low intracellular bile acid concentration by inducing basolateral export. Modeling the autoregulation of bile acids on hepatocytes, we found that BSEP-deficient i-Heps suppressed de novo bile acid synthesis using the FXR pathway via basolateral uptake and export without apical export. These observations inform the development of therapeutic targets to reduce the overall bile acid pool in patients with BSEP deficiency.
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Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/fisiología , Ácidos y Sales Biliares/metabolismo , Hepatocitos/citología , Hepatocitos/metabolismo , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Transporte Biológico , Sistemas CRISPR-Cas , Técnicas de Cultivo de Célula/métodos , Diferenciación Celular , Células Cultivadas , Edición Génica , Humanos , Modelos Biológicos , MutaciónRESUMEN
The stability of mRNA influences the abundance of cellular transcripts and proteins. Deadenylases play critical roles in mRNA turnover and thus are important for the regulation of various biological events. Here, we report the identification and characterization of CCR4b/CNOT6L, which is homologous to yeast CCR4 mRNA deadenylase. CCR4b is localized mainly in the cytoplasm and displays deadenylase activity both in vitro and in vivo. CCR4b forms a multisubunit complex similar to the yeast CCR4-NOT complex. Suppression of CCR4b by RNA interference results in growth retardation of NIH 3T3 cells accompanied by elevation of both p27(Kip1) mRNA and p27(Kip1) protein. Reintroduction of wild-type CCR4b, but not mutant CCR4b lacking deadenylase activity, restores the growth of CCR4b-depleted NIH 3T3 cells. The data suggest that CCR4b regulates cell growth in a manner dependent on its deadenylase activity. We also show that p27(Kip1) mRNA is stabilized and its poly(A) tail is preserved in CCR4b-depleted cells. Our findings provide evidence that CCR4b deadenylase is a constituent of the mammalian CCR4-NOT complex and regulates the turnover rate of specific target mRNAs. Thus, CCR4b may be involved in various cellular events that include cell proliferation.
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Inhibidor p27 de las Quinasas Dependientes de la Ciclina/genética , Ribonucleasas/deficiencia , Animales , Ciclo Celular , Línea Celular , Proliferación Celular , Clonación Molecular , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , ADN Complementario , Exorribonucleasas/metabolismo , Regulación de la Expresión Génica , Humanos , Ratones , Células 3T3 NIH , Poli A/metabolismo , Unión Proteica , Transporte de Proteínas , Estabilidad del ARN , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ribonucleasas/química , Fracciones Subcelulares/metabolismo , Distribución TisularRESUMEN
Almost all life forms can detect and decode light information for adaptive advantage. Examples include the visual system, in which photoreceptor signals are processed into virtual images, and the circadian system, in which light entrains a physiological clock. Here we describe a light response pathway in mice that employs encephalopsin (OPN3, a 480 nm, blue-light-responsive opsin) to regulate the function of adipocytes. Germline null and adipocyte-specific conditional null mice show a light- and Opn3-dependent deficit in thermogenesis and become hypothermic upon cold exposure. We show that stimulating mouse adipocytes with blue light enhances the lipolysis response and, in particular, phosphorylation of hormone-sensitive lipase. This response is Opn3 dependent. These data establish a key mechanism in which light-dependent, local regulation of the lipolysis response in white adipocytes regulates energy metabolism.
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Adipocitos Marrones/metabolismo , Adipocitos Marrones/efectos de la radiación , Adipocitos Blancos/metabolismo , Adipocitos Blancos/efectos de la radiación , Luz , Opsinas de Bastones/metabolismo , Termogénesis/efectos de la radiación , Animales , Frío , Metabolismo Energético/efectos de la radiación , Perfilación de la Expresión Génica , Lipólisis/efectos de la radiación , Ratones Endogámicos C57BL , Fenotipo , Fotones , Termogénesis/genéticaRESUMEN
The abundant in neuroepithelium area (ana) gene was originally identified as a member of the tob/btg family of antiproliferative genes. Like the other family members, Ana inhibits growth of NIH3T3 cells when overexpressed. However, whether or not Ana is involved in tumor progression has been elusive. Here, we show that expression of ana is relatively high in the lung, the expression being restricted in type II alveolar epithelial cells. We further show that ana expression is reduced in 97% of the human lung cancer cell lines examined (61/63) and 86% of clinical samples from lung adenocarcinoma patients (36/42). Long-term observation of ana-deficient (ana−/) mice reveals that 8% of them develop lung tumors (5/66) by 21 months after birth, while 0% of wild-type mice (0/35) develop the same type of tumors. We also show that exogenously expressed ana gene product suppresses the levels of matrix metalloproteinase-2 (MMP-2) and plasminogen activator inhibitor-1 (PAI-1) expression in lung cancer cells. Taken together, we propose that ana functions as a tumor suppressor and that its product inhibits tumor progression as well by suppressing angiogenesis, invasion, and metastasis.
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Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Proteínas/metabolismo , Proteínas/fisiología , Adenocarcinoma/genética , Adulto , Anciano , Anciano de 80 o más Años , Animales , Proteínas de Ciclo Celular , Proliferación Celular , Femenino , Humanos , Pulmón/metabolismo , Pulmón/patología , Neoplasias Pulmonares/genética , Masculino , Metaloproteinasa 2 de la Matriz/genética , Metaloproteinasa 2 de la Matriz/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Persona de Mediana Edad , Células 3T3 NIH , Inhibidor 1 de Activador Plasminogénico/genética , Inhibidor 1 de Activador Plasminogénico/metabolismo , Proteínas/genética , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Exosomes are nano-scale membrane-encapsulated vesicles produced by the majority of cells and have emerged as a rich source of biomarkers for a wide variety of diseases. Although many approaches have been developed for exosome isolation from biofluids, most of them have substantial shortcomings including long processing time, inefficiency, high cost, lack of specificity and/or surface marker-dependency. To address these issues, here we report a novel insulator-based dielectrophoretic (iDEP) device predicated on an array of borosilicate micropipettes to rapidly isolate exosomes from conditioned cell culture media and biofluids, such as plasma, serum, and saliva. The device is capable of exosome isolation from small sample volumes of 200 µL within 20 minutes under a relatively low (10 V cm-1) direct current (DC). This device is easy to fabricate thus, no cleanroom facility and expensive equipment are needed. Therefore, the iDEP device offers a rapid and cost-effective strategy for exosome isolation from biofluids in timely manner while maintaining the yield and purity.