RESUMO
Measuring cellular and tissue mechanics inside intact living organisms is essential for interrogating the roles of force in physiological and disease processes. Current agents for studying the mechanobiology of intact, living organisms are limited by poor light penetration and material stability. Magnetomotive ultrasound is an emerging modality for real-time in vivo imaging of tissue mechanics. Nonetheless, it has poor sensitivity and spatiotemporal resolution. Here we describe magneto-gas vesicles (MGVs), protein nanostructures based on gas vesicles and magnetic nanoparticles that produce differential ultrasound signals in response to varying mechanical properties of surrounding tissues. These hybrid nanomaterials significantly improve signal strength and detection sensitivity. Furthermore, MGVs enable non-invasive, long-term and quantitative measurements of mechanical properties within three-dimensional tissues and in vivo fibrosis models. Using MGVs as novel contrast agents, we demonstrate their potential for non-invasive imaging of tissue elasticity, offering insights into mechanobiology and its application to disease diagnosis and treatment.
Assuntos
Nanopartículas , Nanoestruturas , Diagnóstico por Imagem/métodos , Proteínas/química , Acústica , Nanopartículas/químicaRESUMO
BACKGROUND: We previously identified ezetimibe, an inhibitor of Niemann-Pick C1-like intracellular cholesterol transporter 1 and European Medicines Agency-approved lipid-lowering agent, as a potent autophagy activator. However, its efficacy against pulmonary fibrosis has not yet been evaluated. This study aimed to determine whether ezetimibe has therapeutic potential against idiopathic pulmonary fibrosis. METHODS: Primary lung fibroblasts isolated from both humans and mice were employed for mechanistic in vitro experiments. mRNA sequencing of human lung fibroblasts and gene set enrichment analysis were performed to explore the therapeutic mechanism of ezetimibe. A bleomycin-induced pulmonary fibrosis mouse model was used to examine in vivo efficacy of the drug. Tandem fluorescent-tagged microtubule-associated protein 1 light chain 3 transgenic mice were used to measure autophagic flux. Finally, the medical records of patients with idiopathic pulmonary fibrosis from three different hospitals were reviewed retrospectively, and analyses on survival and lung function were conducted to determine the benefits of ezetimibe. RESULTS: Ezetimibe inhibited myofibroblast differentiation by restoring the mechanistic target of rapamycin complex 1-autophagy axis with fine control of intracellular cholesterol distribution. Serum response factor, a potential autophagic substrate, was identified as a primary downstream effector in this process. Similarly, ezetimibe ameliorated bleomycin-induced pulmonary fibrosis in mice by inhibiting mechanistic target of rapamycin complex 1 activity and increasing autophagic flux, as observed in mouse lung samples. Patients with idiopathic pulmonary fibrosis who regularly used ezetimibe showed decreased rates of all-cause mortality and lung function decline. CONCLUSION: Our study presents ezetimibe as a potential novel therapeutic for idiopathic pulmonary fibrosis.
Assuntos
Anticolesterolemiantes , Autofagia , Modelos Animais de Doenças , Reposicionamento de Medicamentos , Ezetimiba , Fibrose Pulmonar Idiopática , Ezetimiba/uso terapêutico , Ezetimiba/farmacologia , Animais , Fibrose Pulmonar Idiopática/tratamento farmacológico , Humanos , Camundongos , Autofagia/efeitos dos fármacos , Masculino , Anticolesterolemiantes/uso terapêutico , Anticolesterolemiantes/farmacologia , Feminino , Camundongos Transgênicos , Bleomicina , Pulmão/patologia , Pulmão/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/efeitos dos fármacos , Estudos Retrospectivos , Idoso , Pessoa de Meia-Idade , Camundongos Endogâmicos C57BL , Miofibroblastos/efeitos dos fármacos , Miofibroblastos/metabolismo , Colesterol/metabolismoRESUMO
BACKGROUND AND AIMS: Currently there is no Food and Drug Administration-approved drug to treat NAFLD and NASH, the rates of which are increasing worldwide. Although NAFLD/NASH are highly complex and heterogeneous conditions, most pharmacotherapy pipelines focus on a single mechanistic target. Considering the importance of the gut-liver axis in their pathogenesis, we investigated the therapeutic effect of a long-acting dual agonist of glucagon-like peptide (GLP)-1 and GLP-2 receptors in mice with NAFLD/NASH. APPROACH AND RESULTS: C57BL/6J mice were fed a choline-deficient high-fat diet/high fructose and sucrose solution. After 16 weeks, mice were randomly allocated to receive vehicle, GLP1-Fc, GLP2-Fc, or GLP1/2-Fc fusion (GLP1/2-Fc) subcutaneously every 2 days for 4 weeks. Body weight was monitored, insulin/glucose tolerance tests were performed, feces were collected, and microbiome profiles were analyzed. Immobilized cell systems were used to evaluate direct peptide effect. Immunohistochemistry, quantitative PCR, immunoblot analysis, tunnel assay, and biochemical assays were performed to assess drug effects on inflammation, hepatic fibrosis, cell death, and intestinal structures. The mice had well-developed NASH phenotypes. GLP1/2-Fc reduced body weight, glucose levels, hepatic triglyceride levels, and cellular apoptosis. It improved liver fibrosis, insulin sensitivity, and intestinal tight junctions, and increased microvillus height, crypt depth, and goblet cells of intestine compared with a vehicle group. Similar effects of GLP1/2-Fc were found in in vitro cell systems. GLP1/2-Fc also changed microbiome profiles. We applied fecal microbiota transplantation (FMT) gain further insight into the mechanism of GLP1/2-Fc-mediated protection. We confirmed that FMT exerted an additive effect on GLP1-Fc group, including the body weight change, liver weight, hepatic fat accumulation, inflammation, and hepatic fibrosis. CONCLUSIONS: A long-acting dual agonist of GLP-1 and GLP-2 receptors is a promising therapeutic strategy to treat NAFLD/NASH.
Assuntos
Microbiota , Hepatopatia Gordurosa não Alcoólica , Animais , Peso Corporal , Dieta Hiperlipídica/efeitos adversos , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 2/metabolismo , Inflamação/metabolismo , Fígado/patologia , Cirrose Hepática/complicações , Camundongos , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/patologiaRESUMO
BACE1 is the rate-limiting enzyme for amyloid-ß peptides (Aß) generation, a key event in the pathogenesis of Alzheimer's disease (AD). By an unknown mechanism, levels of BACE1 and a BACE1 mRNA-stabilizing antisense RNA (BACE1-AS) are elevated in the brains of AD patients, implicating that dysregulation of BACE1 expression plays an important role in AD pathogenesis. We found that nuclear factor erythroid-derived 2-related factor 2 (NRF2/NFE2L2) represses the expression of BACE1 and BACE1-AS through binding to antioxidant response elements (AREs) in their promoters of mouse and human. NRF2-mediated inhibition of BACE1 and BACE1-AS expression is independent of redox regulation. NRF2 activation decreases production of BACE1 and BACE1-AS transcripts and Aß production and ameliorates cognitive deficits in animal models of AD. Depletion of NRF2 increases BACE1 and BACE1-AS expression and Aß production and worsens cognitive deficits. Our findings suggest that activation of NRF2 can prevent a key early pathogenic process in AD.
Assuntos
Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Transtornos Cognitivos/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Doença de Alzheimer/patologia , Secretases da Proteína Precursora do Amiloide/genética , Peptídeos beta-Amiloides/metabolismo , Animais , Ácido Aspártico Endopeptidases/genética , Transtornos Cognitivos/patologia , Modelos Animais de Doenças , Regulação da Expressão Gênica , Humanos , Isotiocianatos/farmacologia , Camundongos , Camundongos Transgênicos , Fator 2 Relacionado a NF-E2/biossíntese , Regiões Promotoras Genéticas , Ligação Proteica , Espécies Reativas de Oxigênio/metabolismo , Sulfóxidos , Transcrição GênicaRESUMO
Adipogenesis, a critical process that converts adipocyte precursors into adipocytes, is considered a potential therapeutic target for the treatment of obesity. Ezetimibe, a drug approved by the United States Food and Drug Administration, is used for the treatment of hypercholesterolemia. Recently, it was reported to ameliorate high fat diet-induced dyslipidemia in mice and reduce lipid accumulation in hepatocytes through the activation of AMPK. However, the anti-adipogenic effects of ezetimibe and the underlying molecular mechanism have not yet been elucidated. Here, we found that ezetimibe reduced lipid accumulation via activating AMPK during the early phase of adipogenesis. We also observed that ezetimibe inhibited peroxisome proliferator-activated receptor γ, which is a major transcription factor of adipogenesis. Furthermore, ezetimibe-mediated AMPK activation reduced lipid accumulation by inhibiting mTORC1 signaling, leading to the downregulation of lipogenesis-related genes. Mitotic clonal expansion, required for adipogenesis, accelerates cell cycle progression and cell proliferation. We additionally observed that ezetimibe prevented the progression of mitotic clonal expansion by arresting the cell cycle at the G0/G1 phase, which was followed by the inhibition of cell proliferation. Collectively, ezetimibe-mediated inhibition of adipogenesis is dependent on the AMPK-mTORC1 pathway. Thus, we suggest that ezetimibe might be a promising drug for the treatment of obesity.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Adipogenia/efeitos dos fármacos , Ezetimiba/farmacologia , Metabolismo dos Lipídeos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Células 3T3-L1 , Animais , Compostos Azo , Proliferação de Células , Ativação Enzimática , Regulação da Expressão Gênica , Camundongos , PPAR gama/metabolismo , RNA Interferente Pequeno/metabolismo , Transdução de SinaisRESUMO
Certain members of the peroxiredoxin (Prx) family undergo inactivation through hyperoxidation of the catalytic cysteine to sulfinic acid during catalysis and are reactivated by sulfiredoxin; however, the physiological significance of this reversible regulatory process is unclear. We now show that PrxIII in mouse adrenal cortex is inactivated by H(2)O(2) produced by cytochrome P450 enzymes during corticosterone production stimulated by adrenocorticotropic hormone. Inactivation of PrxIII triggers a sequence of events including accumulation of H(2)O(2), activation of p38 mitogen-activated protein kinase, suppression of steroidogenic acute regulatory protein synthesis, and inhibition of steroidogenesis. Interestingly, levels of inactivated PrxIII, activated p38, and sulfiredoxin display circadian oscillations. Steroidogenic tissue-specific ablation of sulfiredoxin in mice resulted in the persistent accumulation of inactive PrxIII and suppression of the adrenal circadian rhythm of corticosterone production. The coupling of CYP11B1 activity to PrxIII inactivation provides a feedback regulatory mechanism for steroidogenesis that functions independently of the hypothalamic-pituitary-adrenal axis.
Assuntos
Glândulas Suprarrenais/metabolismo , Retroalimentação Fisiológica , Peróxido de Hidrogênio/metabolismo , Mitocôndrias/metabolismo , Peroxirredoxina III/metabolismo , Animais , Colesterol/metabolismo , Corticosterona/biossíntese , Camundongos , Camundongos Transgênicos , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Peroxirredoxina III/fisiologia , Fosfoproteínas/metabolismo , Fosforilação , Esteroide 11-beta-Hidroxilase/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Carbonyl cyanide m-chlorophenyl hydrazone (CCCP) is a mitochondrial depolarizing agent that induces reactive oxygen species (ROS)-mediated cell death. The Nrf2-Keap1 pathway is crucial for the elimination of ROS in stressed cells. However, the molecular mechanism underlying the regulation of the Nrf2-Keap1 pathway in CCCP-induced cell death is unknown. In this study, we demonstrated that CCCP promotes Keap1 degradation, and thereby activates Nrf2. This CCCP-mediated Keap1 degradation is partly dependent on autophagy. Moreover, CCCP-induced Keap1 degradation is mainly reliant on p62, which functions as an adaptor protein during selective autophagy. Lack of p62 blocked CCCP-induced Keap1 degradation and inhibited Nrf2 activation, and thereby increased the accumulation of ROS. Ablation of p62 increased the susceptibility of cells to oxidative stress. These results indicate that p62 plays an important role in protecting cells against oxidative stress through Keap1 degradation-mediated Nrf2 activation.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Proteínas de Choque Térmico/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Linhagem Celular , Fibroblastos/efeitos dos fármacos , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Proteína Sequestossoma-1RESUMO
Peroxisome proliferator-activated receptor α (PPARα) activates the ß-oxidation of fatty acids in the liver. Fenofibrate is a potent agonist of PPARα and is used in the treatment of hyperlipidemia. Fenofibrate treatment often induces the production of intracellular reactive oxygen species (ROS), leading to cell death. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway is an essential component of the defense mechanism against oxidative stress. However, the molecular mechanism underlying the regulation of the Nrf2-Keap1 pathway in fenofibrate-induced cell death is not known. In this study, we demonstrated that fenofibrate induces Keap1 degradation and Nrf2 activation. This fenofibrate-mediated Keap1 degradation is partly dependent on autophagy. Furthermore, fenofibrate-induced Keap1 degradation followed by Nrf2 activation is mainly mediated by p62, which functions as an adaptor protein in the autophagic pathway. Consistent with these findings, ablation of p62 increased fenofibrate-mediated apoptotic cell death associated with ROS accumulation. These results strongly suggest that p62 plays a crucial role in preventing fenofibrate-induced cell death.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas do Citoesqueleto/metabolismo , Fenofibrato/administração & dosagem , Fibroblastos/citologia , Fibroblastos/metabolismo , Proteínas de Choque Térmico/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Fibroblastos/efeitos dos fármacos , Hipolipemiantes/administração & dosagem , Proteína 1 Associada a ECH Semelhante a Kelch , Camundongos , Espécies Reativas de Oxigênio/metabolismo , Proteína Sequestossoma-1RESUMO
p70 ribosomal S6 kinase 1 (S6K1) is an important serine/threonine kinase and downstream target of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. PF-4708671 is a specific inhibitor of S6K1, and prevents S6K1-mediated phosphorylation of the S6 protein. PF-4708671 treatment often leads to apoptotic cell death. However, the protective mechanism against PF-4708671-induced cell death has not been elucidated. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway is essential for protecting cells against oxidative stress. p62, an adaptor protein in the autophagic process, enhances Nrf2 activation through the impairment of Keap1 activity. In this study, we showed that PF-4708671 induces autophagic Keap1 degradation-mediated Nrf2 activation in p62-dependent manner. Furthermore, p62-dependent Nrf2 activation plays a crucial role in protecting cells from PF-4708671-mediated apoptosis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas de Choque Térmico/metabolismo , Imidazóis/farmacologia , Fator 2 Relacionado a NF-E2/metabolismo , Piperazinas/farmacologia , Proteínas Quinases S6 Ribossômicas 90-kDa/antagonistas & inibidores , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Autofagia/efeitos dos fármacos , Autofagia/fisiologia , Células Cultivadas , Proteínas do Citoesqueleto/genética , Células HeLa , Proteínas de Choque Térmico/deficiência , Proteínas de Choque Térmico/genética , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch , Camundongos , Inibidores de Proteínas Quinases/farmacologia , Proteólise/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteína Sequestossoma-1 , Transdução de Sinais/efeitos dos fármacosRESUMO
Nonalcoholic fatty liver disease (NAFLD), frequently associated with obesity and diabetes mellitus, is caused by the accumulation of excess fatty acids within liver cells. Palmitic acid (PA), a common saturated fatty acid found in mammals, induces the generation of reactive oxygen species (ROS) and elicits apoptotic cell death, known as lipotoxicity. However, protective mechanisms against PA-induced lipotoxicity have not been elucidated. In this study, we aimed to clarify the role of p62, an adapter protein in the autophagic process, as well as the nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway, in protecting cells from PA-induced lipotoxicity. The Nrf2-Keap1 pathway is essential for the protection of cells from oxidative stress. p62 enhances its binding to Keap1 and leads to Nrf2 activation. Here, we show that PA potentiates Keap1 degradation and thereby activates the transcription of Nrf2 target genes partially through autophagy. Furthermore, this PA-mediated Keap1 degradation depends on p62. Correspondingly, a lack of p62 attenuates the PA-mediated Nrf2 activation and increases the susceptibility of cells to oxidative stress. These results indicate that p62 plays an important role in protecting cells against lipotoxicity through Keap1 degradation-mediated Nrf2 activation.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas de Choque Térmico/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Ácido Palmítico/metabolismo , Proteólise , Animais , Apoptose , Autofagia , Linhagem Celular , Proteína 1 Associada a ECH Semelhante a Kelch , Camundongos , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Proteína Sequestossoma-1RESUMO
Insulin activates sterol regulatory element-binding protein-1c (SREBP-1c) in liver, thereby increasing fatty acid and triglyceride synthesis. We created a line of transgenic rats that produce epitope-tagged human SREBP-1c in liver under control of the constitutive apolipoprotein E promoter/enhancer. This system allows us to dissect the pathway by which insulin stimulates SREBP-1c processing without interference by the insulin-mediated increase in SREBP-1c mRNA. Rats are used because freshly isolated rat hepatocytes respond much more robustly to insulin than do mouse hepatocytes. The data reveal that insulin-mediated stimulation of SREBP-1c processing requires the mechanistic target of rapamycin complex 1 (mTORC1), which also is required for insulin-mediated SREBP-1c mRNA induction. However, in contrast to mRNA induction, insulin stimulation of SREBP-1c processing is blocked by an inhibitor of p70 S6-kinase. The data indicate that the pathways for insulin enhancement of SREBP-1c mRNA and proteolytic processing diverge after mTORC1. Stimulation of processing requires the mTORC1 target p70 S6-kinase, whereas induction of mRNA bypasses this enzyme. Insulin stimulation of both processes is blocked by glucagon. The transgenic rat system will be useful in further defining the molecular mechanism for insulin stimulation of lipid synthesis in liver in normal and diabetic states.
Assuntos
Insulina/farmacologia , Lipogênese/fisiologia , Fígado/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Animais , Apolipoproteínas E/genética , Primers do DNA/genética , Técnicas de Transferência de Genes , Glucagon , Humanos , Immunoblotting , Alvo Mecanístico do Complexo 1 de Rapamicina , Complexos Multiproteicos , Proteínas/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Transgênicos , Reação em Cadeia da Polimerase em Tempo Real , Proteínas Quinases S6 Ribossômicas 70-kDa/antagonistas & inibidores , Serina-Treonina Quinases TORRESUMO
Transcriptional coactivator with a PDZ-binding motif (TAZ) plays a key role in normal tissue homeostasis and tumorigenesis through interaction with several transcription factors. In particular, TAZ deficiency causes abnormal alveolarization and emphysema, and persistent TAZ overexpression contributes to lung cancer and pulmonary fibrosis, suggesting the possibility of a complex mechanism of TAZ function. Recent studies suggest that nuclear factor erythroid 2-related factor 2 (NRF2), an antioxidant defense system, induces TAZ expression during tumorigenesis and that TAZ also activates the NRF2-mediated antioxidant pathway. We thus thought to elucidate the cross-regulation of TAZ and NRF2 and the underlying molecular mechanisms and functions. TAZ directly interacted with NRF2 through the N-terminal domain and suppressed the transcriptional activity of NRF2 by preventing NRF2 from binding to DNA. In addition, the return of NRF2 to basal levels after signaling was inhibited in TAZ deficiency, resulting in sustained nuclear NRF2 levels and aberrantly increased expression of NRF2 targets. TAZ deficiency failed to modulate optimal NRF2 signaling and concomitantly impaired lysosomal acidification and lysosomal enzyme function, accumulating the abnormal autophagy vesicles and reactive oxygen species and causing protein oxidation and cellular damage in the lungs. TAZ restoration to TAZ deficiency normalized dysregulated NRF2 signaling and aberrant lysosomal function and triggered the normal autophagy-lysosomal pathway. Therefore, TAZ is indispensable for the optimal regulation of NRF2-mediated autophagy-lysosomal pathways and for preventing pulmonary damage caused by oxidative stress and oxidized proteins.
Assuntos
Autofagia , Lisossomos , Fator 2 Relacionado a NF-E2 , Fator 2 Relacionado a NF-E2/metabolismo , Autofagia/fisiologia , Lisossomos/metabolismo , Animais , Camundongos , Humanos , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional/metabolismo , Transdução de Sinais , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Espécies Reativas de Oxigênio/metabolismo , Proteínas Adaptadoras de Transdução de SinalRESUMO
Peroxiredoxins (Prxs) contain an active site cysteine that is sensitive to oxidation by H(2)O(2). Mammalian cells express six Prx isoforms that are localized to various cellular compartments. The oxidized active site cysteine of Prx can be reduced by a cellular thiol, thus enabling Prx to function as a locally constrained peroxidase. Regulation of Prx via phosphorylation in response to extracellular signals allows the local accumulation of H(2)O(2) and thereby enables its messenger function. The fact that the oxidation state of the active site cysteine of Prx can be transferred to other proteins that are less intrinsically susceptible to H(2)O(2) also allows Prx to function as an H(2)O(2) sensor.
Assuntos
Cisteína/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidase/metabolismo , Peroxirredoxinas/metabolismo , Sistemas do Segundo Mensageiro/fisiologia , Animais , Domínio Catalítico/fisiologia , Humanos , Isoenzimas/metabolismo , Oxirredução , Fosforilação/fisiologiaRESUMO
Sulfiredoxin (Srx) is an enzyme that catalyzes the reduction of cysteine sulfinic acid of hyperoxidized peroxiredoxins (Prxs). Having high affinity toward H2O2, 2-Cys Prxs can efficiently reduce H2O2 at low concentration. We previously showed that Prx I is hyperoxidized at a rate of 0.072% per turnover even in the presence of low steady-state levels of H2O2. Here we examine the novel role of Srx in cells exposed to low steady-state levels of H2O2, which can be achieved by using glucose oxidase. Exposure of low steady-state levels of H2O2 (10-20 µm) to A549 or wild-type mouse embryonic fibroblast (MEF) cells does not lead to any significant change in oxidative injury because of the maintenance of balance between H2O2 production and elimination. In contrast, loss-of-function studies using Srx-depleted A549 and Srx-/- MEF cells demonstrate a dramatic increase in extra- and intracellular H2O2, sulfinic 2-Cys Prxs, and apoptosis. Concomitant with hyperoxidation of mitochondrial Prx III, Srx-depleted cells show an activation of mitochondria-mediated apoptotic pathways including mitochondria membrane potential collapse, cytochrome c release, and caspase activation. Furthermore, adenoviral re-expression of Srx in Srx-depleted A549 or Srx-/- MEF cells promotes the reactivation of sulfinic 2-Cys Prxs and results in cellular resistance to apoptosis, with enhanced removal of H2O2. These results indicate that Srx functions as a novel component to maintain the balance between H2O2 production and elimination and then protects cells from apoptosis even in the presence of low steady-state levels of H2O2.
Assuntos
Peróxido de Hidrogênio/farmacologia , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Animais , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Caspase 9/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Citocromos c/metabolismo , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Técnicas de Inativação de Genes , Humanos , Peróxido de Hidrogênio/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/deficiência , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/genética , RNA Interferente Pequeno/genética , Transdução de Sinais/efeitos dos fármacosRESUMO
INTRODUCTION: Cholesterol is an irreplaceable nutrient in pulmonary metabolism; however, studies on high-density lipoprotein cholesterol (HDL-C) levels have shown conflicting results regarding lung function. Therefore, we investigated the association between lung function and HDL-C levels in three cross-sectional studies conducted in the USA and South Korea. METHODS: US National Health and Nutrition Examination Survey (NHANES) III, US NHANES 2007-2012, and Korea National Health and Nutrition Examination Survey (KNHANES) IV-VII performed spirometry and met the American Thoracic Society recommendations. Multiple linear regression models were used to determine the relationship between serum lipid levels and lung function. The models were adjusted for age, sex, household income, body mass index, smoking pack year, use of lipid-lowering medication and race. Serum HDL-C levels were classified into three groups to assess the dose-response relationship according to the guideline from the National Cholesterol Education Program-Adult Treatment Panel III. RESULTS: The adult participants of the KNHANES (n=31 288), NHANES III (n=12 182) and NHANES 2007-2012 (n=9122) were analysed. Multivariate linear regression analysis of the serum cholesterol profiles revealed that only serum HDL-C was associated with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) in all three studies. A 1 SD increase in the HDL-C level increased the percent predicted FVC by 0.5%-1.5% p, and the per cent predicted FEV1 by 0.5%-1.7% p. In terms of HDL-C levels, correlations between the HDL-C groups and the per cent predicted FVC and FEV1 showed dose-response relationships. Compared with the normal group, high HDL-C levels increased FVC by 0.75%-1.79% p and FEV1 by 0.55%-1.90% p, while low levels led to 0.74%-2.19% p and 0.86%-2.68% p reductions in FVC and FEV1, respectively. Subgroup analyses revealed weaker associations in females from KNHANES and NHANES III. CONCLUSION: In the three nationwide cross-sectional studies, high HDL-C levels were associated with improved FVC and FEV1. However, future studies are needed to confirm this correlation and elucidate the underlying mechanisms.
Assuntos
Colesterol , Pulmão , Feminino , Humanos , Adulto , Estados Unidos/epidemiologia , Inquéritos Nutricionais , Estudos Transversais , República da Coreia/epidemiologia , Lipoproteínas HDLRESUMO
Nonalcoholic steatohepatitis (NASH) is associated with imbalance of gut microbiome, indicating participation of gut environment in hepatic health status. Therefore, modulating gut environment via fecal microbiota transplantation (FMT) is a promising therapeutic procedure for NASH patients. However, the effect and mechanism of the FMT remains largely unknown. Here, we investigated the gut-liver axis to understand the FMT-mediated hepatic improvement in NASH. Feces from specific pathogen free mice were infused allogeneically into gastrointestinal tract of mice fed with high fat, high cholesterol and fructose (HFHCF), resulting in suppressing hepatic pathogenic events, featured by decreasing inflammatory and fibrotic mediators. The FMT elevated NF-E2-related factor 2 (NRF2), a key transcription factor that regulates antioxidant enzymes, in livers. The HFHCF-induced NASH increased intestinal permeability with abundant Facklamia and Aerococcus, an imbalanced gut environment that was significantly improved by the FMT, characterized with restoration of intestinal barrier function and an enrichment of Clostridium. Notably, the gut environment created by FMT was inferred to produce metabolites from the aromatic biogenic amine degradation pathway, specifically 4-hydroxyphenylacetic acid (4-HPA), which is known to ameliorate liver injury. We suggest that gut-derived molecules, related to hepatic improvement such as 4-HPA are the potential therapeutic agents for preventing and treating NASH.
Assuntos
Hepatopatia Gordurosa não Alcoólica , Humanos , Animais , Camundongos , Hepatopatia Gordurosa não Alcoólica/terapia , Transplante de Microbiota Fecal , Estresse Oxidativo , Inflamação/terapia , Inflamação/patologiaRESUMO
Ferroptosis, a type of cell death induced by lipid peroxidation, has emerged as a novel anti-cancer strategy. Cancer cells frequently acquire resistance to ferroptosis. However, the underlying mechanisms are poorly understood. To address this issue, we conducted a thorough investigation of the genomic and transcriptomic data derived from hundreds of human cancer cell lines and primary tissue samples, with a particular focus on non-small cell lung carcinoma (NSCLC). It was observed that mutations in Kelch-like ECH-associated protein 1 (KEAP1) and subsequent nuclear factor erythroid 2-related factor 2 (NRF2, also known as NFE2L2) activation are strongly associated with ferroptosis resistance in NSCLC. Additionally, AIFM2 gene, which encodes ferroptosis suppressor protein 1 (FSP1), was identified as the gene most significantly correlated with ferroptosis resistance, followed by multiple NRF2 targets. We found that inhibition of NRF2 alone was not sufficient to reduce FSP1 protein levels and promote ferroptosis, whereas FSP1 inhibition effectively sensitized KEAP1-mutant NSCLC cells to ferroptosis. Furthermore, we found that combined inhibition of FSP1 and NRF2 induced ferroptosis more intensely. Our findings imply that FSP1 is a crucial suppressor of ferroptosis whose expression is partially dependent on NRF2 and that synergistically targeting both FSP1 and NRF2 may be a promising strategy for overcoming ferroptosis resistance in cancer.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Ferroptose , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/genética , Ferroptose/genética , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Neoplasias Pulmonares/genética , Fator 2 Relacionado a NF-E2/genéticaRESUMO
UNLABELLED: Peroxiredoxins (Prxs) are peroxidases that catalyze the reduction of reactive oxygen species (ROS). The active site cysteine residue of members of the 2-Cys Prx subgroup (Prx I to IV) of Prxs is hyperoxidized to cysteine sulfinic acid (Cys-SO(2) ) during catalysis with concomitant loss of peroxidase activity. Reactivation of the hyperoxidized Prx is catalyzed by sulfiredoxin (Srx). Ethanol consumption induces the accumulation of cytochrome P450 2E1 (CYP2E1), a major contributor to ethanol-induced ROS production in the liver. We now show that chronic ethanol feeding markedly increased the expression of Srx in the liver of mice in a largely Nrf2-dependent manner. Among Prx I to IV, only Prx I was found to be hyperoxidized in the liver of ethanol-fed wildtype mice, and the level of Prx I-SO(2) increased to ≈30% to 50% of total Prx I in the liver of ethanol-fed Srx(-/-) mice. This result suggests that Prx I is the most active 2-Cys Prx in elimination of ROS from the liver of ethanol-fed mice and that, despite the up-regulation of Srx expression by ethanol, the capacity of Srx is not sufficient to counteract the hyperoxidation of Prx I that occurs during ROS reduction. A protease protection assay revealed that a large fraction of Prx I is located together with CYP2E1 at the cytosolic side of the endoplasmic reticulum membrane. The selective role of Prx I in ROS removal is thus likely attributable to the proximity of Prx I and CYP2E1. CONCLUSION: The pivotal functions of Srx and Prx I in protection of the liver in ethanol-fed mice was evident from the severe oxidative damage observed in mice lacking either Srx or Prx I.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Etanol/toxicidade , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Peroxirredoxinas/metabolismo , Animais , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Citocromo P-450 CYP2E1/metabolismo , Masculino , Camundongos , Oxirredução , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/deficiência , Peroxirredoxina III , Espécies Reativas de Oxigênio/metabolismoRESUMO
Hepatic lipotoxicity is a crucial factor in nonalcoholic steatohepatitis resulting from excessive saturated fatty acid-induced reactive oxygen species (ROS)-mediated cell death, which is associated with the accumulation of endoplasmic reticulum (ER) stress in the liver. The unfolded protein response (UPR) alleviates ER stress by restoring ER protein folding homeostasis. However, whether UPR contributes ROS elimination under lipotoxicity remains unclear. The Kelch like ECH-associated protein 1 (KEAP1)-nuclear factor, erythroid 2 like 2 (Nrf2) pathway provides antioxidant defense against lipotoxic stress by eliminating ROS and can be activated by the p62-Unc-51 like autophagy activating kinase 1 (ULK1) axis. However, the upstream molecular regulator of the p62-ULK1 axis-induced KEAP1-Nrf2 pathway in the same context remains unidentified. Here, we demonstrated that PKR-like ER kinase (PERK), a UPR sensor, directly phosphorylates p62 and ULK1, thereby activating the noncanonical KEAP1-Nrf2 pathway. We also elucidated the molecular mechanism underlying the PERK-mediated p62-ULK1 axis-dependent noncanonical KEAP1-Nrf2 pathway, which could represent a promising therapeutic strategy against hepatic lipotoxicity.
Assuntos
Proteína 1 Associada a ECH Semelhante a Kelch , Fígado , Fator 2 Relacionado a NF-E2 , Proteínas Serina-Treonina Quinases , eIF-2 Quinase , Autofagia , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fígado/metabolismo , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Proteína Sequestossoma-1/genética , Proteína Sequestossoma-1/metabolismo , eIF-2 Quinase/metabolismoRESUMO
Although autophagy is critical for pancreatic ß-cell function, the role and mechanism of mitophagy in ß-cells are unclear. We studied the role of lysosomal Ca2+ in TFEB activation by mitochondrial or metabolic stress and that of TFEB-mediated mitophagy in ß-cell function. Mitochondrial or metabolic stress induced mitophagy through lysosomal Ca2+ release, increased cytosolic Ca2+ and TFEB activation. Lysosomal Ca2+ replenishment by ER- > lysosome Ca2+ refilling was essential for mitophagy. ß-cell-specific Tfeb knockout (TfebΔß-cell) abrogated high-fat diet (HFD)-induced mitophagy, accompanied by increased ROS and reduced mitochondrial cytochrome c oxidase activity or O2 consumption. TfebΔß-cell mice showed aggravation of HFD-induced glucose intolerance and impaired insulin release. Metabolic or mitochondrial stress induced TFEB-dependent expression of mitophagy receptors including Ndp52 and Optn, contributing to the increased mitophagy. These results suggest crucial roles of lysosomal Ca2+ release coupled with ER- > lysosome Ca2+ refilling and TFEB activation in mitophagy and maintenance of pancreatic ß-cell function during metabolic stress.