RESUMEN
Protein kinase R (PKR), a key double-stranded RNA (dsRNA)-activated sensor, is pivotal for cellular responses to diverse stimuli. This protocol delineates a comprehensive methodological framework employing single luciferase assays, yeast assays, immunoblot assays, and quantitative PCR (qPCR) to discern and validate PKR activities and their downstream impacts on NF-κB-activating signaling pathways. These methodologies furnish a systematic approach to unraveling the role of PKR as a dsRNA sensor and effector in antiviral innate immunity, enabling in-depth analyses of dsRNA sensor activities.
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Inmunidad Innata , ARN Bicatenario , eIF-2 Quinasa , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , ARN Bicatenario/inmunología , ARN Bicatenario/genética , Humanos , FN-kappa B/metabolismo , Transducción de Señal , AnimalesRESUMEN
Cisplatin is a common anticancer drug, but its frequent nephrotoxicity limits its clinical use. Small GTP-binding protein GDP dissociation stimulator (smgGDS), a small GTPase chaperone protein, was considerably downregulated during cisplatin-induced acute kidney injury (CDDP-AKI), especially in renal tubular epithelial cells. SmgGDS-knockdown mice was established and found that smgGDS knockdown promoted CDDP-AKI, as demonstrated by an increase in serum creatine, blood urea nitrogen levels and the appearance of tubular patterns. RNA sequencing suggested that protein kinase RNA-like ER kinase (PERK), which bridges mitochondria-associated ER membranes, was involved in smgGDS knockdown following CDDP-AKI, and then identified that smgGDS knockdown increased phosphorylated-PERK in vivo and in vitro. Furthermore, we confirmed that smgGDS deficiency aggravated apoptosis and ER stress in vivo and in vitro. And the ER stress inhibitor 4-Phenylbutyric acid and the inhibition of PERK phosphorylation mitigated smgGDS deficiency-induced ER stress related apoptosis following cisplatin treatment, while the eIF2α phosphorylation inhibitor could not reverse the smgGDS deficiency accelerated cell death. Furthermore, the over-expression of smgGDS could reverse the ER stress and apoptosis caused by CDDP. Overall, smgGDS regulated PERK-dependent ER stress and apoptosis, thereby influencing renal damage. This study identified a target for diagnosing and treating cisplatin-induced acute kidney injury.
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Lesión Renal Aguda , Cisplatino , Estrés del Retículo Endoplásmico , eIF-2 Quinasa , Cisplatino/efectos adversos , Cisplatino/toxicidad , Animales , Lesión Renal Aguda/inducido químicamente , Lesión Renal Aguda/metabolismo , Lesión Renal Aguda/patología , Lesión Renal Aguda/genética , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Estrés del Retículo Endoplásmico/efectos de los fármacos , Ratones , Masculino , Apoptosis/efectos de los fármacos , Ratones Endogámicos C57BL , Antineoplásicos/efectos adversos , Antineoplásicos/toxicidad , FosforilaciónRESUMEN
BACKGROUND: Acute myeloid leukemia (AML) is characterized by the abnormal proliferation of myeloid precursor cells and presents significant challenges in treatment due to its heterogeneity. Recently, the NLRP3 inflammasome has emerged as a potential contributor to AML pathogenesis, although its precise mechanisms remain poorly understood. METHODS: Public genome datasets were utilized to evaluate the expression of NLRP3 inflammasome-related genes (IL-1ß, IL-18, ASC, and NLRP3) in AML patients compared to healthy individuals. CRISPR/Cas9 technology was employed to generate NLRP3-deficient MOLM-13 AML cells, followed by comprehensive characterization using real-time PCR, western blotting, FACS analysis, and transmission electron and immunofluorescence microscopy. Proteomic analyses were conducted to identify NLRP3-dependent alterations in protein levels, with a focus on the eIF2 kinase PERK-mediated signaling pathways. Additionally, in vivo studies were performed using a leukemic mouse model to elucidate the pathogenic role of NLRP3 in AML. RESULTS: Elevated expression of NLRP3 was significantly associated with diminished overall survival in AML patients. Genetic deletion, pharmacological inhibition and silencing by RNA interference of NLRP3 led to decreased AML cell survival through the induction of apoptosis. Proteomic analyses uncovered NLRP3-dependent alterations in protein translation, characterized by enhanced eIF2α phosphorylation in NLRP3-deficient AML cells. Moreover, inhibition of PERK-mediated eIF2α phosphorylation reduced apoptosis by downregulating pro-apoptotic Bcl-2 family members. In vivo studies demonstrated reduced leukemic burden in mice engrafted with NLRP3 knockout AML cells, as evidenced by alleviated leukemic symptoms. CONCLUSION: Our findings elucidate the involvement of the NLRP3/PERK/eIF2 axis as a novel driver of AML cell survival. Targeting NLRP3-induced signaling pathways, particularly through the PERK/eIF2 axis, presents a promising therapeutic strategy for AML intervention. These insights into the role of the NLRP3 inflammasome offer potential avenues for improving the prognosis and treatment outcomes of AML patients.
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Apoptosis , Factor 2 Eucariótico de Iniciación , Leucemia Mieloide Aguda , Proteína con Dominio Pirina 3 de la Familia NLR , eIF-2 Quinasa , Leucemia Mieloide Aguda/patología , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/genética , Humanos , Apoptosis/genética , Animales , Factor 2 Eucariótico de Iniciación/metabolismo , Factor 2 Eucariótico de Iniciación/genética , Ratones , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Transducción de Señal , Línea Celular Tumoral , Progresión de la Enfermedad , Inflamasomas/metabolismoRESUMEN
Recent investigations have revealed that oxidative stress can lead to neuronal damage and disrupt mitochondrial and endoplasmic reticulum functions after intracerebral hemorrhage (ICH). However, there is limited evidence elucidating their role in maintaining neuronal homeostasis. Metabolomics analysis, RNA sequencing, and CUT&Tag-seq were performed to investigate the mechanism underlying the interaction between the PERK/ATF4 branch of the endoplasmic reticulum stress (ERS) and mitochondrial one-carbon (1C) metabolism during neuronal resistance to oxidative stress. The association between mitochondrial 1C metabolism and the PERK/ATF4 branch of the ERS after ICH was investigated using transcription factor motif analysis and co-immunoprecipitation. The findings revealed interactions between the GRP78/PERK/ATF4 and mitochondrial 1C metabolism, which are important in preserving neuronal homeostasis after ICH. ATF4 is an upstream transcription factor that directly regulates the expression of 1C metabolism genes. Additionally, the GRP78/PERK/ATF4 forms a negative regulatory loop with MTHFD2 because of the interaction between GRP78 and MTHFD2. This study presents evidence of disrupted 1C metabolism and the occurrence of ERS in neurons post-ICH. Supplementing exogenous NADPH or interfering with the PERK/ATF4 could reduce symptoms related to neuronal injuries, suggesting new therapeutic prospects for ICH.
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Factor de Transcripción Activador 4 , Hemorragia Cerebral , Estrés del Retículo Endoplásmico , Mitocondrias , Neuronas , eIF-2 Quinasa , Factor de Transcripción Activador 4/metabolismo , Estrés del Retículo Endoplásmico/fisiología , Animales , Neuronas/metabolismo , eIF-2 Quinasa/metabolismo , Hemorragia Cerebral/metabolismo , Mitocondrias/metabolismo , Chaperón BiP del Retículo Endoplásmico/metabolismo , Carbono/metabolismo , Ratas , Ratones , Masculino , Ratas Sprague-Dawley , Estrés OxidativoRESUMEN
The double-stranded DNA (dsDNA) sensor STING has been increasingly implicated in responses to "sterile" endogenous threats and pathogens without nominal DNA or cyclic di-nucleotide stimuli. Previous work showed an endoplasmic reticulum (ER) stress response, known as the unfolded protein response (UPR), activates STING. Herein, we sought to determine if ER stress generated a STING ligand, and to identify the UPR pathways involved. Induction of IFN-ß expression following stimulation with the UPR inducer thapsigargin (TPG) or oxygen glucose deprivation required both STING and the dsDNA-sensing cyclic GMP-AMP synthase (cGAS). Furthermore, TPG increased cytosolic mitochondrial DNA, and immunofluorescence visualized dsDNA punctae in murine and human cells, providing a cGAS stimulus. N-acetylcysteine decreased IFN-ß induction by TPG, implicating reactive oxygen species (ROS). However, mitoTEMPO, a mitochondrial oxidative stress inhibitor did not impact TPG-induced IFN. On the other hand, inhibiting the inositol requiring enzyme 1 (IRE1) ER stress sensor and its target transcription factor XBP1 decreased the generation of cytosolic dsDNA. iNOS upregulation was XBP1-dependent, and an iNOS inhibitor decreased cytosolic dsDNA and IFN-ß, implicating ROS downstream of the IRE1-XBP1 pathway. Inhibition of the PKR-like ER kinase (PERK) pathway also attenuated cytoplasmic dsDNA release. The PERK-regulated apoptotic factor Bim was required for both dsDNA release and IFN-ß mRNA induction. Finally, XBP1 and PERK pathways contributed to cytosolic dsDNA release and IFN-induction by the RNA virus, Vesicular Stomatitis Virus (VSV). Together, our findings suggest that ER stressors, including viral pathogens without nominal STING or cGAS ligands such as RNA viruses, trigger multiple canonical UPR pathways that cooperate to activate STING and downstream IFN-ß via mitochondrial dsDNA release.
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Citosol , Estrés del Retículo Endoplásmico , Interferón beta , Proteínas de la Membrana , Nucleotidiltransferasas , Respuesta de Proteína Desplegada , Humanos , Animales , Ratones , Nucleotidiltransferasas/metabolismo , Citosol/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Interferón beta/metabolismo , ADN/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , eIF-2 Quinasa/metabolismo , Endorribonucleasas/metabolismo , Proteína 1 de Unión a la X-Box/metabolismo , Proteína 1 de Unión a la X-Box/genética , Tapsigargina/farmacología , Especies Reactivas de Oxígeno/metabolismo , Activación Transcripcional , ADN Mitocondrial/metabolismoRESUMEN
Endoplasmic reticulum (ER) stress induces the repression of protein synthesis throughout the cell. Attempts to understand how localized stress leads to widespread repression have been limited by difficulties in resolving translation rates at the subcellular level. Here, using live-cell imaging of reporter mRNA translation, we unexpectedly found that during ER stress, active translation at mitochondria was significantly protected. The mitochondrial protein ATPase family AAA domain-containing protein 3A (ATAD3A) interacted with protein kinase RNA-like endoplasmic reticulum kinase (PERK) and mediated this effect on localized translation by competing for binding with PERK's target, eukaryotic initiation factor 2 (eIF2). PERK-ATAD3A interactions increased during ER stress, forming mitochondria-ER contact sites. Furthermore, ATAD3A binding attenuated local PERK signaling and rescued the expression of some mitochondrial proteins. Thus, PERK-ATAD3A interactions can control translational repression at a subcellular level, mitigating the impact of ER stress on the cell.
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ATPasas Asociadas con Actividades Celulares Diversas , Estrés del Retículo Endoplásmico , Factor 2 Eucariótico de Iniciación , Proteínas de la Membrana , Proteínas Mitocondriales , Biosíntesis de Proteínas , eIF-2 Quinasa , Humanos , ATPasas Asociadas con Actividades Celulares Diversas/metabolismo , ATPasas Asociadas con Actividades Celulares Diversas/genética , eIF-2 Quinasa/metabolismo , Retículo Endoplásmico/metabolismo , Factor 2 Eucariótico de Iniciación/metabolismo , Células HEK293 , Células HeLa , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Proteínas Mitocondriales/genética , Unión Proteica , ARN Mensajero/metabolismo , ARN Mensajero/genética , Transducción de Señal , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismoRESUMEN
Adar null mutant mouse embryos die with aberrant double-stranded RNA (dsRNA)-driven interferon induction, and Adar Mavs double mutants, in which interferon induction is prevented, die soon after birth. Protein kinase R (Pkr) is aberrantly activated in Adar Mavs mouse pup intestines before death, intestinal crypt cells die, and intestinal villi are lost. Adar Mavs Eifak2 (Pkr) triple mutant mice rescue all defects and have long-term survival. Adenosine deaminase acting on RNA 1 (ADAR1) and PKR co-immunoprecipitate from cells, suggesting PKR inhibition by direct interaction. AlphaFold studies on an inhibitory PKR dsRNA binding domain (dsRBD)-kinase domain interaction before dsRNA binding and on an inhibitory ADAR1 dsRBD3-PKR kinase domain interaction on dsRNA provide a testable model of the inhibition. Wild-type or editing-inactive human ADAR1 expressed in A549 cells inhibits activation of endogenous PKR. ADAR1 dsRNA binding is required for, but is not sufficient for, PKR inhibition. Mutating the ADAR1 dsRBD3-PKR contact prevents co-immunoprecipitation, ADAR1 inhibition of PKR activity, and co-localization of ADAR1 and PKR in cells.
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Adenosina Desaminasa , ARN Bicatenario , Proteínas de Unión al ARN , eIF-2 Quinasa , Adenosina Desaminasa/metabolismo , Adenosina Desaminasa/genética , eIF-2 Quinasa/metabolismo , ARN Bicatenario/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Humanos , Animales , Ratones , Unión Proteica , Activación Enzimática , Células A549 , Dominios ProteicosRESUMEN
Self and nonself discrimination is fundamental to immunity. However, it remains largely enigmatic how the mechanisms of distinguishing nonself from self originated. As an intracellular nucleic acid sensor, protein kinase R (PKR) recognizes double-stranded RNA (dsRNA) and represents a crucial component of antiviral innate immunity. Here, we combine phylogenomic and functional analyses to show that PKR proteins probably originated from a preexisting kinase protein through acquiring dsRNA binding domains at least before the last common ancestor of jawed vertebrates during or before the Silurian period. The function of PKR appears to be conserved across jawed vertebrates. Moreover, we repurpose a protein closely related to PKR proteins into a putative dsRNA sensor, recapturing the making of PKR. Our study illustrates how a nucleic acid sensor might have originated via molecular tinkering with preexisting proteins and provides insights into the origins of innate immunity.
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Evolución Molecular , Filogenia , Vertebrados , eIF-2 Quinasa , Animales , Vertebrados/genética , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , ARN Bicatenario/metabolismo , Inmunidad Innata , Humanos , Ácidos Nucleicos/metabolismo , Evolución BiológicaRESUMEN
Objective To explore the effects of Myxovirus resistance protein A (MxA) on the Janus kinase/Signal transducer and activator of transcription (JAK/STAT) pathway in HepG2 cells. Methods HepG2 cells were transfected with the pcDNA3.1-Flag-MxA construct, and subsequent localization and expression of the MxA protein were detected through immunofluorescence cytochemistry. The presence of MxA protein was further confirmed by using Western blot analysis. Following transfection with MxA small interfering RNA (si-MxA) and subsequent treatment with alpha interferon (IFN-α), real-time fluorescent quantitative PCR was employed to measure the mRNA levels of myxovirus resistance protein A (MxA), protein kinase R (PKR), and oligoadenylate synthase (OAS). Western blot analysis was used to detect the protein expression of MxA, PKR, OAS, signal transducer and activator of transcription 1 (STAT1), phosphorylated STAT1 (pSTAT1), STAT2, phosphorylated STAT2 (p-STAT2) and interferon regulatory factor 9 (IRF9). Additionally, pcDNA3.1-Flag-MxA and pISRE-TA-luc were co-transfected into HepG2 and HepG2.2.15 cells, respectively, to assess the activity of the interferon-stimulated response element (ISRE) by using a luciferase activity assay. Results MxA protein was expressed in both the cytoplasm and nucleus of HepG2 cells, with higher expression levels in the cytoplasm than in the nucleus. Knocking down MxA expression in HepG2 cells did not affect the expression of STAT1, p-STAT1, STAT2, p-STAT2, and IRF9 proteins induced by IFN-α, but significantly reduced the expression of antiviral proteins PKR and OAS. Overexpression of MxA in HepG2 cells enhanced ISRE activity and increased the expression of PKR and OAS proteins, but this effect was inhibited in HepG2.2.15 cells. Conclusion MxA induces the expression of antiviral proteins by enhancing the activity of the JAK/STAT signaling pathway ISRE.
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2',5'-Oligoadenilato Sintetasa , Proteínas de Resistencia a Mixovirus , Factor de Transcripción STAT1 , eIF-2 Quinasa , Humanos , Células Hep G2 , Proteínas de Resistencia a Mixovirus/genética , Proteínas de Resistencia a Mixovirus/metabolismo , 2',5'-Oligoadenilato Sintetasa/genética , 2',5'-Oligoadenilato Sintetasa/metabolismo , eIF-2 Quinasa/genética , eIF-2 Quinasa/metabolismo , Factor de Transcripción STAT1/genética , Factor de Transcripción STAT1/metabolismo , Interferón-alfa/farmacología , Interferón-alfa/genética , Interferón-alfa/metabolismo , Elementos de Respuesta/genética , Transducción de Señal , Factor de Transcripción STAT2/genética , Factor de Transcripción STAT2/metabolismo , Interferones/genética , Interferones/metabolismo , Subunidad gamma del Factor 3 de Genes Estimulados por el Interferón/genética , Subunidad gamma del Factor 3 de Genes Estimulados por el Interferón/metabolismo , Regulación de la Expresión GénicaRESUMEN
Some negative-sense RNA viruses, including measles virus (MeV), share the characteristic that during their infection cycle, cytoplasmic inclusion bodies (IBs) are formed where components of the viral replication machinery are concentrated. As a foci of viral replication, how IBs act to enhance the efficiency of infection by affecting virus-host interactions remains an important topic of investigation. We previously established that upon MeV infection, the epigenetic host protein, WD repeat-containing protein 5 (WDR5), translocates to cytoplasmic viral IBs and facilitates MeV replication. We now show that WDR5 is recruited to IBs by forming a complex with IB-associated MeV phosphoprotein via a conserved binding motif located on the surface of WDR5. Furthermore, we provide evidence that WDR5 promotes viral replication by suppressing a major innate immune response pathway, the double-stranded RNA-mediated activation of protein kinase R and integrated stress response. IMPORTANCE: MeV is a pathogen that remains a global concern, with an estimated 9 million measles cases and 128,000 measles deaths in 2022 according to the World Health Organization. A large population of the world still has inadequate access to the effective vaccine against the exceptionally transmissible MeV. Measles disease is characterized by a high morbidity in children and in immunocompromised individuals. An important area of research for negative-sense RNA viruses, including MeV, is the characterization of the complex interactome between virus and host occurring at cytoplasmic IBs where viral replication occurs. Despite the progress made in understanding IB structures, little is known regarding the virus-host interactions within IBs and the role of these interactions in promoting viral replication and antagonizing host innate immunity. Herein we provide evidence suggesting a model by which MeV IBs utilize the host protein WDR5 to suppress the protein kinase R-integrated stress response pathway.
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Inmunidad Innata , Virus del Sarampión , Sarampión , Replicación Viral , Virus del Sarampión/fisiología , Virus del Sarampión/genética , Humanos , Sarampión/virología , Sarampión/metabolismo , Cuerpos de Inclusión Viral/metabolismo , Interacciones Huésped-Patógeno , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Células HEK293 , Estrés Fisiológico , ARN Bicatenario/metabolismo , Proteínas Virales/metabolismo , Proteínas Virales/genética , AnimalesRESUMEN
The integrated stress response (ISR) is a vital signaling pathway initiated by four kinases, PERK, GCN2, HRI and PKR, that ensure cellular resilience and protect cells from challenges. Here, we investigated whether increasing ISR signaling could rescue diabetes-like phenotypes in a mouse model of diet-induced obesity (DIO). We show that the orally available and clinically approved GCN2 activator halofuginone (HF) can activate the ISR in mouse tissues. We found that daily oral administration of HF increases glucose tolerance whilst reducing weight gain, insulin resistance, and serum insulin in DIO mice. Conversely, the ISR inhibitor GSK2656157, used at low doses to optimize its selectivity, aggravates glucose intolerance in DIO mice. Whilst loss of function mutations in mice and humans have revealed that PERK is the essential ISR kinase that protects from diabetes, our work demonstrates the therapeutic value of increasing ISR signaling by activating the related kinase GCN2 to reduce diabetes phenotypes in a DIO mouse model.
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Obesidad , Fenotipo , Piperidinas , Proteínas Serina-Treonina Quinasas , Quinazolinonas , Transducción de Señal , eIF-2 Quinasa , Animales , Quinazolinonas/farmacología , Piperidinas/farmacología , Ratones , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Obesidad/patología , Obesidad/metabolismo , Obesidad/prevención & control , Obesidad/genética , Transducción de Señal/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Ratones Endogámicos C57BL , Masculino , Resistencia a la Insulina , Insulina/metabolismo , Insulina/sangre , Estrés Fisiológico/efectos de los fármacos , Modelos Animales de Enfermedad , Dieta Alta en Grasa/efectos adversos , Diabetes Mellitus/patología , Diabetes Mellitus/metabolismo , Diabetes Mellitus/genética , Diabetes Mellitus/tratamiento farmacológico , Diabetes Mellitus/prevención & control , Intolerancia a la Glucosa/tratamiento farmacológico , Adenina/análogos & derivados , IndolesRESUMEN
HIV disease remains prevalent in the USA and chronic kidney disease remains a major cause of morbidity in HIV-1-positive patients. Host double-stranded RNA (dsRNA)-activated protein kinase (PKR) is a sensor for viral dsRNA, including HIV-1. We show that PKR inhibition by compound C16 ameliorates the HIV-associated nephropathy (HIVAN) kidney phenotype in the Tg26 transgenic mouse model, with reversal of mitochondrial dysfunction. Combined analysis of single-nucleus RNA-seq and bulk RNA-seq data revealed that oxidative phosphorylation was one of the most downregulated pathways and identified signal transducer and activator of transcription (STAT3) as a potential mediating factor. We identified in Tg26 mice a novel proximal tubular cell cluster enriched in mitochondrial transcripts. Podocytes showed high levels of HIV-1 gene expression and dysregulation of cytoskeleton-related genes, and these cells dedifferentiated. In injured proximal tubules, cell-cell interaction analysis indicated activation of the pro-fibrogenic PKR-STAT3-platelet-derived growth factor (PDGF)-D pathway. These findings suggest that PKR inhibition and mitochondrial rescue are potential novel therapeutic approaches for HIVAN.
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Nefropatía Asociada a SIDA , Ratones Transgénicos , Mitocondrias , eIF-2 Quinasa , Animales , Humanos , Ratones , Nefropatía Asociada a SIDA/genética , Nefropatía Asociada a SIDA/metabolismo , Nefropatía Asociada a SIDA/patología , Modelos Animales de Enfermedad , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , VIH-1/genética , VIH-1/fisiología , Mitocondrias/metabolismo , Podocitos/metabolismo , Factor de Transcripción STAT3/metabolismo , Factor de Transcripción STAT3/genéticaRESUMEN
Nonalcoholic fatty liver disease (NAFLD) is a liver disease causing different progressive pathological changes. Trimethylamine N-oxide (TMAO), a product of gut microbiota metabolism, is a specific agonist of the protein kinase R-like endoplasmic reticulum kinase (PERK) pathway, one of the endoplasmic reticulum stress (ERS) pathways. TMAO has been associated with the occurrence and development of NAFLD based on the results of previous studies, but whether the simple consumption of TMAO can directly induce NAFLD and its underlying mechanism remain unclear. To investigate this question, we constructed an animal model in which adult male zebrafish were fed a controlled diet containing 1â¯% or 3â¯% TMAO for 20 weeks. Eventually, we observed that TMAO caused lipid accumulation, inflammatory infiltration, liver injury and liver fibrosis in zebrafish livers; meanwhile, the PERK signaling pathway was activated in the zebrafish livers. This finding was further confirmed in HepG2 cells and hepatic stellate cells models. In conclusion, this study found that TMAO directly induced different pathological states of NAFLD in zebrafish liver, and the activation of PERK pathway is an important mechanism, which may provide crucial strategies for the diagnosis and treatment of NAFLD.
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Estrés del Retículo Endoplásmico , Metilaminas , Enfermedad del Hígado Graso no Alcohólico , Pez Cebra , eIF-2 Quinasa , Metilaminas/toxicidad , Metilaminas/metabolismo , Animales , Enfermedad del Hígado Graso no Alcohólico/inducido químicamente , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/patología , Masculino , eIF-2 Quinasa/metabolismo , Humanos , Células Hep G2 , Estrés del Retículo Endoplásmico/efectos de los fármacos , Hígado/efectos de los fármacos , Hígado/patología , Hígado/metabolismo , Modelos Animales de Enfermedad , Transducción de Señal/efectos de los fármacos , Células Estrelladas Hepáticas/efectos de los fármacos , Células Estrelladas Hepáticas/metabolismo , Células Estrelladas Hepáticas/patología , Metabolismo de los Lípidos/efectos de los fármacos , Cirrosis Hepática/inducido químicamente , Cirrosis Hepática/patología , Cirrosis Hepática/metabolismoRESUMEN
Colorectal cancer (CRC) ranks among the leading causes of cancer-related deaths worldwide. Enhancing CRC diagnosis and prognosis requires the development of improved biomarkers and therapeutic targets. Emerging evidence suggests that the unfolded protein response (UPR) plays a pivotal role in CRC progression, presenting new opportunities for diagnosis, treatment, and prevention. This study hypothesizes that genetic variants in endoplasmic reticulum (ER) stress response genes influence CRC susceptibility. We examined the frequencies of SNPs in PERK (rs13045) and GRP78/BiP (rs430397) within a South Iranian cohort. We mapped the cellular and molecular features of PERK and GRP78 genes in colorectal cancer, observing their differential expressions in tumor and metastatic tissues. We constructed co-expression and protein-protein interaction networks and performed gene set enrichment analysis, highlighting autophagy as a significant pathway through KEGG. Furthermore, the study included 64 CRC patients and 60 control subjects. DNA extraction and genotyping were conducted using high-resolution melting (HRM) analysis. Significant differences in PERK and GRP78 expressions were observed between CRC tissues and controls. Variations in PERK and GRP78 genotypes were significantly correlated with CRC risk. Utilizing a Multi-Target Directed Ligands approach, a dual PERK/GRP78 inhibitor was designed and subjected to molecular modeling studies. Docking experiments indicated high-affinity binding between the proposed inhibitor and both genes, PERK and GRP78, suggesting a novel therapy for CRC. These findings highlight the importance of understanding genetic backgrounds in different populations to assess CRC risk. Polymorphisms in UPR signaling pathway elements may serve as potential markers for predicting CRC susceptibility, paving the way for personalized therapeutic strategies.
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Neoplasias Colorrectales , Chaperón BiP del Retículo Endoplásmico , Proteínas de Choque Térmico , Polimorfismo de Nucleótido Simple , eIF-2 Quinasa , Humanos , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Neoplasias Colorrectales/tratamiento farmacológico , eIF-2 Quinasa/genética , eIF-2 Quinasa/metabolismo , Masculino , Femenino , Proteínas de Choque Térmico/genética , Persona de Mediana Edad , Simulación del Acoplamiento Molecular , Regulación Neoplásica de la Expresión Génica , Predisposición Genética a la Enfermedad , Terapia Molecular Dirigida , Anciano , Estrés del Retículo Endoplásmico/genética , Estrés del Retículo Endoplásmico/efectos de los fármacos , Mapas de Interacción de Proteínas/genéticaRESUMEN
The mitochondrial unfolded protein response (UPRmt) is triggered through eIF2α phosphorylation in mammals. However, the mechanisms of UPRmt activation and the influence of eIF2α phosphorylation on mitochondrial protein translation remain unclear. In this study, we confirmed that the UPRmt is a rapid and specific stress response that occurs through pharmacological induction of eIF2α phosphorylation, along with the phosphorylation of eIF2α, ATF4, and CHOP. Moreover, with the upregulation of the expression of some chaperones, cytochrome P450 enzymes, and DDIT4, as determined by RNA-Seq and ribosome profiling, eIF2α phosphorylation was found to be essential for the expression of ATF4 and CHOP, after which ATF4 trafficked into the nucleus and initiated CHOP expression. In addition, the generation of ROS and mitochondrial morphology were not affected by the GTPP-induced UPRmt. Furthermore, we investigated the mechanism by which HRI kinase-mediated UPRmt is induced by mitochondrial unfolded proteins via CRISPR-Cas9 technology, mitochondrial recruitment of HRI and interaction with other proteins. Moreover, we confirmed that mitochondrial protein translation and mitochondrial protein import were inhibited through eIF2α phosphorylation with the accumulation of unfolded mitochondrial proteins. These findings reveal the molecular mechanism of the UPRmt and its impact on cellular protein translation, which will offer novel insights into the functions of the UPRmt, including its implications for human disease and pathobiology.
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Factor de Transcripción Activador 4 , Factor 2 Eucariótico de Iniciación , Mitocondrias , Proteínas Mitocondriales , Biosíntesis de Proteínas , Respuesta de Proteína Desplegada , Mitocondrias/metabolismo , Humanos , Proteínas Mitocondriales/metabolismo , Factor 2 Eucariótico de Iniciación/metabolismo , Fosforilación , Factor de Transcripción Activador 4/metabolismo , Factor de Transcripción CHOP/metabolismo , Células HEK293 , Animales , eIF-2 Quinasa/metabolismoRESUMEN
The endoplasmic reticulum (ER) is an essential organelle that maintains intracellular Ca2+ homeostasis, folds newly synthesized secreted and membrane proteins, and facilitates post-translational protein modifications. Misfolding and aggregation of unfolded proteins within the ER lumen can activate endoplasmic reticulum stress (ERS), which in turn activates three different downstream signaling pathways: protein kinase R-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α(IRE-1α), and activating transcription factor 6 (ATF6). These pathways affect cell survival, differentiation, and phenotype transition. Recent studies have shown a close interaction between the downstream signaling cascade of ERS and the signaling pathways that induce macrophage polarization towards pro-inflammatory M1 type (IFN-γ and LPS) and anti-inflammatory M2 type (IL-4 and IL-10). However, the specific molecular mechanisms underlying these interactions are complex and intriate. The article summarizes the primary mechanisms by which ERS mediates macrophage polarization, focusing on discussing the molecular mechanisms by which three different downstream signals of ERS affect macrophage polarization.
Asunto(s)
Estrés del Retículo Endoplásmico , Macrófagos , Transducción de Señal , Macrófagos/metabolismo , Humanos , Animales , Factor de Transcripción Activador 6/metabolismo , Factor de Transcripción Activador 6/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/fisiología , Activación de Macrófagos , eIF-2 Quinasa/metabolismo , Retículo Endoplásmico/metabolismo , Polaridad CelularRESUMEN
BACKGROUND/AIM: Breast cancer is the most predominant type of cancer affecting women worldwide and the current therapeutic treatment for breast cancer patients is not adequately effective. This study aimed to investigate the mechanism of 17-AAG, a heat shock protein (HSP90) inhibitor, as a treatment for inducing breast cancer cell apoptosis. MATERIALS AND METHODS: The pharmacology network was employed to examine the correlation of 17-AAG with the gene expression profiles of breast cancer, obtained by Gene Expression Profiling Interactive Analysis (GEPIA). MTT and flow cytometry were utilized to investigate cell proliferation and cell apoptosis, respectively. Dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay and western blot analysis were employed to examine the correlation between cellular oxidant levels and protein expression. Immunofluorescence staining was utilized to confirm the protein localization and assess DNA damage. RESULTS: The pharmacological network analysis revealed that HSP90 serves as the common target connecting 17-AAG and breast cancer genes. Treatment with 17-AAG significantly increased cell apoptosis. Moreover, the treatment resulted in up-regulation of cellular oxidant levels and PERK/eIF2α expression. In line with these, protein localization after treatment revealed an increase in DNA damage, correlating with higher ER stress levels. Furthermore, GEPIA demonstrated that PERK and eIF2α expression were significantly higher in breast invasive carcinoma compared to other tumor types. CONCLUSION: HSP90 emerges as a potential target for inducing apoptosis in breast cancer cells by disrupting protein homeostasis in the endoplasmic reticulum, possibly through PERK/eIF2α up-regulation. 17-AAG, an HSP90 inhibitor, may therefore potentially hold an alternative therapeutic strategy for breast cancer treatment.
Asunto(s)
Apoptosis , Benzoquinonas , Neoplasias de la Mama , Estrés del Retículo Endoplásmico , Factor 2 Eucariótico de Iniciación , Lactamas Macrocíclicas , eIF-2 Quinasa , Humanos , Benzoquinonas/farmacología , Lactamas Macrocíclicas/farmacología , Apoptosis/efectos de los fármacos , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/metabolismo , Femenino , Estrés del Retículo Endoplásmico/efectos de los fármacos , Factor 2 Eucariótico de Iniciación/metabolismo , Factor 2 Eucariótico de Iniciación/genética , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Línea Celular Tumoral , Proteínas HSP90 de Choque Térmico/metabolismo , Proteínas HSP90 de Choque Térmico/genética , Proliferación Celular/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacosRESUMEN
The study investigates the therapeutic effects and mechanisms of ginsenoside Rg_1(GRg_1) on sepsis-induced acute lung injury(SALI). A murine model of SALI was created using cecal ligation and puncture(CLP) surgery, and mice were randomly assigned to groups for GRg_1 intervention. Survival and body weight changes were recorded, lung function was assessed with a non-invasive lung function test system, and lung tissue damage was evaluated through HE staining. The content and expression of inflammatory factors were measured by ELISA and qRT-PCR. Apoptosis was examined using flow cytometry and TUNEL staining. The activation and expression of apoptosis-related molecules cysteinyl aspartate specific proteinase 3(caspase-3), B-cell lymphoma-2(Bcl-2), Bcl-2 associated X protein(Bax), and endoplasmic reticulum stress-related molecules protein kinase R-like endoplasmic reticulum kinase(PERK), eukaryotic initiation factor 2α(eIF2α), activating transcription factor 4(ATF4), and C/EBP homologous protein(CHOP) were studied using Western blot and qRT-PCR. In addition, an in vitro model of lipopolysaccharide(LPS)-induced lung alveolar epithelial cell injury was used, with the application of the endoplasmic reticulum stress inducer tunicamycin to validate the action mechanism of GRg_1. RESULTS:: indicated that, when compared to the model group, GRg_1 intervention significantly enhanced the survival time of CLP mice, mitigated body weight loss, and improved impaired lung function indices. The GRg_1-treated mice also displayed reduced lung tissue pathological scores, a reduced lung tissue wet-to-dry weight ratio, and lower protein content in the bronchoalveolar lavage fluid. Serum levels of interleukin-6(IL-6), interleukin-1ß(IL-1ß), and tumor necrosis factor-α(TNF-α), as well as the mRNA expressions of these cytokines in lung tissues, were decreased. There was a notable decrease in the proportion of apopto-tic alveolar epithelial cells, and down-regulated expressions of caspase-3, Bax, PERK, eIF2α, ATF4, and CHOP and up-regulated expression of Bcl-2 were observed. In vitro findings showed that the apoptosis-lowering and apoptosis-related protein down-regulating effects of GRg_1 were significantly inhibited with the co-application of tunicamycin. Altogether, GRg_1 reduces apoptosis of alveolar epithelial cells, inhibits inflammation in the lungs, alleviates lung injury, and enhances lung function, possibly through the PERK/eIF2α/ATF4/CHOP pathway.
Asunto(s)
Factor de Transcripción Activador 4 , Lesión Pulmonar Aguda , Células Epiteliales Alveolares , Apoptosis , Factor 2 Eucariótico de Iniciación , Ginsenósidos , Sepsis , Factor de Transcripción CHOP , eIF-2 Quinasa , Animales , Lesión Pulmonar Aguda/tratamiento farmacológico , Lesión Pulmonar Aguda/metabolismo , Lesión Pulmonar Aguda/genética , Ginsenósidos/farmacología , Factor de Transcripción Activador 4/metabolismo , Factor de Transcripción Activador 4/genética , Ratones , Apoptosis/efectos de los fármacos , Factor de Transcripción CHOP/metabolismo , Factor de Transcripción CHOP/genética , Sepsis/tratamiento farmacológico , Sepsis/complicaciones , Sepsis/metabolismo , Sepsis/genética , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Factor 2 Eucariótico de Iniciación/metabolismo , Factor 2 Eucariótico de Iniciación/genética , Masculino , Células Epiteliales Alveolares/efectos de los fármacos , Células Epiteliales Alveolares/metabolismo , Humanos , Estrés del Retículo Endoplásmico/efectos de los fármacos , Ratones Endogámicos C57BLRESUMEN
Transposable elements (TEs) are mobile genetic modules of viral derivation that have been co-opted to become modulators of mammalian gene expression. TEs are a major source of endogenous dsRNAs, signaling molecules able to coordinate inflammatory responses in various physiological processes. Here, we provide evidence for a positive involvement of TEs in inflammation-driven bone repair and mineralization. In newly fractured mice bone, we observed an early transient upregulation of repeats occurring concurrently with the initiation of the inflammatory stage. In human bone biopsies, analysis revealed a significant correlation between repeats expression, mechanical stress and bone mineral density. We investigated a potential link between LINE-1 (L1) expression and bone mineralization by delivering a synthetic L1 RNA to osteoporotic patient-derived mesenchymal stem cells and observed a dsRNA-triggered protein kinase (PKR)-mediated stress response that led to strongly increased mineralization. This response was associated with a strong and transient inflammation, accompanied by a global translation attenuation induced by eIF2α phosphorylation. We demonstrated that L1 transfection reshaped the secretory profile of osteoblasts, triggering a paracrine activity that stimulated the mineralization of recipient cells.
Asunto(s)
Inflamación , Elementos de Nucleótido Esparcido Largo , Células Madre Mesenquimatosas , eIF-2 Quinasa , Animales , eIF-2 Quinasa/metabolismo , eIF-2 Quinasa/genética , Ratones , Humanos , Inflamación/metabolismo , Inflamación/genética , Inflamación/patología , Células Madre Mesenquimatosas/metabolismo , Elementos de Nucleótido Esparcido Largo/genética , Osteoblastos/metabolismo , Calcificación Fisiológica/genéticaRESUMEN
Yaba monkey tumor virus (YMTV) and Tanapox virus (TPV) are members of the Yatapoxvirus genus and can infect humans and other primates. Despite the threat posed by yatapoxviruses, the factors determining their host range are poorly understood. In this study, we analyzed the ability of YMTV and TPV orthologs of vaccinia virus K3 (called 012 in YMTV and TPV), which share 75% amino acid identity with one another, to inhibit PKR from 15 different primate species. We first used a luciferase-based reporter, and found that YMTV and TPV K3 orthologs inhibited PKR in a species-specific manner and showed distinct PKR inhibition profiles. TPV 012 inhibited PKR from 11 primates, including humans, substantially better than YMTV 012. In contrast, both K3 orthologs inhibited the other four primate PKRs comparably well. Using YMTV 012 and TPV 012 hybrids, we mapped the region responsible for the differential PKR inhibition to the C- terminus of the K3 orthologs. Next, we generated chimeric vaccinia virus strains to investigate whether TPV K3 and YMTV K3 orthologs could rescue the replication of a vaccinia virus strain that lacks PKR inhibitors K3L and E3L. Virus replication in primate-derived cells generally correlated with the patterns observed in the luciferase-based assay. Together, these observations demonstrate that yatapoxvirus K3 orthologs have distinct PKR inhibition profiles and inhibit PKR in a species-specific manner, which may contribute to the differential susceptibility of primate species to yatapoxvirus infections.