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1.
Hepatology ; 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34320238

RESUMO

BACKGROUND AND AIMS: NAFLD has become a tremendous burden for public health; however, there is no drug for NAFLD therapy at present. Impaired endo-lysosome-mediated protein degradation is observed in a variety of metabolic disorders, such as atherosclerosis, type 2 diabetes mellitus, and NAFLD. Small integral membrane protein of lysosome/late endosome (SIMPLE) is a regulator of endosome-to-lysosome trafficking and cell signaling, but the role that SIMPLE plays in NAFLD progression remains unknown. Here we investigated SIMPLE function in NAFLD development and sophisticated mechanism therein. APPROACH AND RESULTS: This study found that in vitro knockdown of SIMPLE significantly aggravated lipid accumulation and inflammation in hepatocytes treated with metabolic stimulation. Consistently, in vivo experiments showed that liver-specific Simple-knockout (Simple-HKO) mice exhibited more severe high-fat diet (HFD)-induced, high-fat-high-cholesterol diet (HFHC)-induced, and methionine-choline-deficient diet (MCD)-induced steatosis, glucose intolerance, inflammation, and fibrosis than those fed with normal chow (NC) diet. Meanwhile, RNA-sequencing demonstrated the up-regulated signaling pathways and signature genes involved in lipid metabolism, inflammation, and fibrosis in Simple-HKO mice compared with control mice under metabolic stress. Mechanically, we found SIMPLE directly interact with epidermal growth factor receptor (EGFR). SIMPLE deficiency results in dysregulated degradation of EGFR, subsequently hyperactivated EGFR phosphorylation, thus exaggerating NAFLD development. Moreover, we demonstrated that using EGFR inhibitor or silencing EGFR expression could ameliorate lipid accumulation induced by the knockdown of SIMPLE. CONCLUSIONS: SIMPLE ameliorated NASH by prompting EGFR degradation and can be a potential therapeutic candidate for NASH.

2.
Cell Metab ; 33(8): 1640-1654.e8, 2021 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-34107313

RESUMO

Obesity is characterized by the excessive accumulation of the white adipose tissue (WAT), but healthy expansion of WAT via adipocyte hyperplasia can offset the negative metabolic effects of obesity. Thus, identification of novel adipogenesis regulators that promote hyperplasia may lead to effective therapies for obesity-induced metabolic disorders. Using transcriptomic approaches, we identified transmembrane BAX inhibitor motif-containing 1 (TMBIM1) as an inhibitor of adipogenesis. Gain or loss of function of TMBIM1 in preadipocytes inhibited or promoted adipogenesis, respectively. In vivo, in response to caloric excess, adipocyte precursor (AP)-specific Tmbim1 knockout (KO) mice displayed WAT hyperplasia and improved systemic metabolic health, while overexpression of Tmbim1 in transgenic mice showed the opposite effects. Moreover, mature adipocyte-specific Tmbim1 KO did not affect WAT cellularity or nutrient homeostasis. Mechanistically, TMBIM1 binds to and promotes the autoubiquitination and degradation of NEDD4, which is an E3 ligase that stabilizes PPARγ. Our data show that TMBIM1 is a potent repressor of adipogenesis and a potential therapeutic target for obesity-related metabolic disease.

3.
Cell Metab ; 33(2): 258-269.e3, 2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33421384

RESUMO

Corticosteroid therapy is now recommended as a treatment in patients with severe COVID-19. But one key question is how to objectively identify severely ill patients who may benefit from such therapy. Here, we assigned 12,862 COVID-19 cases from 21 hospitals in Hubei Province equally to a training and a validation cohort. We found that a neutrophil-to-lymphocyte ratio (NLR) > 6.11 at admission discriminated a higher risk for mortality. Importantly, however, corticosteroid treatment in such individuals was associated with a lower risk of 60-day all-cause mortality. Conversely, in individuals with an NLR ≤ 6.11 or with type 2 diabetes, corticosteroid treatment was not associated with reduced mortality, but rather increased risks of hyperglycemia and infections. These results show that in the studied cohort corticosteroid treatment is associated with beneficial outcomes in a subset of COVID-19 patients who are non-diabetic and with severe symptoms as defined by NLR.


Assuntos
Corticosteroides/uso terapêutico , COVID-19/tratamento farmacológico , Linfócitos/citologia , Neutrófilos/citologia , Corticosteroides/efeitos adversos , Área Sob a Curva , COVID-19/mortalidade , COVID-19/patologia , COVID-19/virologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/patologia , Humanos , Hiperglicemia/complicações , Hiperglicemia/patologia , Tempo de Internação , Modelos de Riscos Proporcionais , Curva ROC , Fatores de Risco , SARS-CoV-2/isolamento & purificação , Índice de Gravidade de Doença , Taxa de Sobrevida , Resultado do Tratamento
4.
Cell Metab ; 32(2): 176-187.e4, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32592657

RESUMO

Statins are lipid-lowering therapeutics with favorable anti-inflammatory profiles and have been proposed as an adjunct therapy for COVID-19. However, statins may increase the risk of SARS-CoV-2 viral entry by inducing ACE2 expression. Here, we performed a retrospective study on 13,981 patients with COVID-19 in Hubei Province, China, among which 1,219 received statins. Based on a mixed-effect Cox model after propensity score-matching, we found that the risk for 28-day all-cause mortality was 5.2% and 9.4% in the matched statin and non-statin groups, respectively, with an adjusted hazard ratio of 0.58. The statin use-associated lower risk of mortality was also observed in the Cox time-varying model and marginal structural model analysis. These results give support for the completion of ongoing prospective studies and randomized controlled trials involving statin treatment for COVID-19, which are needed to further validate the utility of this class of drugs to combat the mortality of this pandemic.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Anti-Hipertensivos/uso terapêutico , Infecções por Coronavirus/tratamento farmacológico , Reposicionamento de Medicamentos/métodos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Pneumonia Viral/tratamento farmacológico , Idoso , Enzima de Conversão de Angiotensina 2 , Betacoronavirus/efeitos dos fármacos , COVID-19 , Comorbidade , Infecções por Coronavirus/mortalidade , Síndrome da Liberação de Citocina/tratamento farmacológico , Quimioterapia Combinada , Feminino , Humanos , Hipertensão/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Pandemias , Peptidil Dipeptidase A/efeitos dos fármacos , Pneumonia Viral/mortalidade , Estudos Retrospectivos , SARS-CoV-2
6.
Circulation ; 137(14): 1486-1504, 2018 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-29229612

RESUMO

BACKGROUND: Cardiac hypertrophy and its resultant heart failure are among the most common causes of mortality worldwide. Abnormal protein degradation, especially the impaired lysosomal degradation of large organelles and membrane proteins, is involved in the progression of cardiac hypertrophy. However, the underlying mechanisms have not been fully elucidated. METHODS: We investigated cardiac transmembrane BAX inhibitor motif containing 1 (TMBIM1) mRNA and protein expression levels in samples from patients with heart failure and mice with aortic banding (AB)-induced cardiac hypertrophy. We generated cardiac-specific Tmbim1 knockout mice and cardiac-specific Tmbim1-overexpressing transgenic mice and then challenged them with AB surgery. We used microarray, confocal image, and coimmunoprecipitation analyses to identify the downstream targets of TMBIM1 in cardiac hypertrophy. Tmbim1/Tlr4 double-knockout mice were generated to investigate whether the effects of TMBIM1 on cardiac hypertrophy were Toll-like receptor 4 (TLR4) dependent. Finally, lentivirus-mediated TMBIM1 overexpression in a monkey AB model was performed to evaluate the therapeutic potential of TMBIM1. RESULTS: TMBIM1 expression was significantly downregulated on hypertrophic stimuli in both human and mice heart samples. Silencing cardiac Tmbim1 aggravated AB-induced cardiac hypertrophy. This effect was blunted by Tmbim1 overexpression. Transcriptome profiling revealed that the TLR4 signaling pathway was disrupted dramatically by manipulation of Tmbim1. The effects of TMBIM1 on cardiac hypertrophy were shown to be dependent on TLR4 in double-knockout mice. Fluorescent staining indicated that TMBIM1 promoted the lysosome-mediated degradation of activated TLR4. Coimmunoprecipitation assays confirmed that TMBIM1 directly interacted with tumor susceptibility gene 101 via a PTAP motif and accelerated the formation of multivesicular bodies that delivered TLR4 to the lysosomes. Finally, lentivirus-mediated TMBIM1 overexpression reversed AB-induced cardiac hypertrophy in monkeys. CONCLUSIONS: TMBIM1 protects against pathological cardiac hypertrophy through promoting the lysosomal degradation of activated TLR4. Our findings reveal the central role of TMBIM1 as a multivesicular body regulator in the progression of pathological cardiac hypertrophy, as well as the role of vesicle trafficking in signaling regulation during cardiac hypertrophy. Moreover, targeting TMBIM1 could be a novel therapeutic strategy for treating cardiac hypertrophy and heart failure.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Cardiomegalia/patologia , Insuficiência Cardíaca/patologia , Motivos de Aminoácidos , Animais , Proteínas Reguladoras de Apoptose/química , Proteínas Reguladoras de Apoptose/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Complexos Endossomais de Distribuição Requeridos para Transporte/química , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Haplorrinos , Humanos , Lisossomos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
7.
Nat Med ; 23(6): 742-752, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28481357

RESUMO

Non-alcoholic steatohepatitis (NASH) is an increasingly prevalent liver pathology that can progress from non-alcoholic fatty liver disease (NAFLD), and it is a leading cause of cirrhosis and hepatocellular carcinoma. There is currently no pharmacological therapy for NASH. Defective lysosome-mediated protein degradation is a key process that underlies steatohepatitis and a well-recognized drug target in a variety of diseases; however, whether it can serve as a therapeutic target for NAFLD and NASH remains unknown. Here we report that transmembrane BAX inhibitor motif-containing 1 (TMBIM1) is an effective suppressor of steatohepatitis and a previously unknown regulator of the multivesicular body (MVB)-lysosomal pathway. Tmbim1 expression in hepatocytes substantially inhibited high-fat diet-induced insulin resistance, hepatic steatosis and inflammation in mice. Mechanistically, Tmbim1 promoted the lysosomal degradation of toll-like receptor 4 by cooperating with the ESCRT endosomal sorting complex to facilitate MVB formation, and the ubiquitination of Tmbim1 by the E3 ubiquitin ligase Nedd4l was required for this process. We also found that overexpression of Tmbim1 in the liver effectively inhibited a severe form of NAFLD in mice and NASH progression in monkeys. Taken together, these findings could lead to the development of promising strategies to treat NASH by targeting MVB regulators to properly orchestrate the lysosome-mediated protein degradation of key mediators of the disease.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Membrana/metabolismo , Corpos Multivesiculares/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Receptor 4 Toll-Like/metabolismo , Adolescente , Adulto , Animais , Western Blotting , Citocinas/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Feminino , Imunofluorescência , Células HEK293 , Células HeLa , Humanos , Imuno-Histoquímica , Lisossomos/metabolismo , Macaca fascicularis , Masculino , Camundongos , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Ubiquitina-Proteína Ligases Nedd4 , Reação em Cadeia da Polimerase , Tomografia por Emissão de Pósitrons , Células RAW 264.7 , Ubiquitina-Proteína Ligases/metabolismo , Adulto Jovem
8.
J Hepatol ; 65(1): 113-124, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27016281

RESUMO

BACKGROUND & AIMS: Dickkopf-3 (DKK3), a protein belonging to the DKK family, has been extensively investigated in the context of cancer, including liver cancer. However, the role of DKK3 in hepatic steatosis and related metabolic disorders remains largely unexplored. METHODS: We detected the expression of DKK3 in the fatty livers of NAFLD patients and of obese mice and investigated the function of DKK3 in hepatic steatosis and related metabolic disorders by using hepatocyte-specific DKK3 deficiency or overexpression obese mice induced by high fat diet (HFD) or genetic defect (ob/ob). The molecular mechanisms underlying DKK3-regulated hepatic steatosis were further explored and verified in mice. RESULTS: DKK3 expression was significantly decreased in the livers of NAFLD patients and of obese mice as well as in cultured hepatocytes stimulated with palmitate. Further investigation indicated that specific overexpression of DKK3 in hepatocytes enhanced insulin sensitivity and glucose tolerance, reduced the inflammatory response, and ameliorated the imbalance of lipid metabolism in response to HFD or genetic defects. In contrast, DKK3 deficiency in hepatocytes led to an almost complete reversal of these pathologies. Mechanistically, DKK3 combined with Apoptosis signal-regulating kinase 1 (ASK1) under palmitate stimulation, and thus inhibited the activation of the downstream P38/JNK pathway. Importantly, dominant-negative ASK1 blocked the accelerated effects of DKK3 deficiency, while the constitutively active form of ASK1 overcame the inhibitory effects of DKK3 overexpression on HFD-induced metabolic disorders in vivo. CONCLUSION: DKK3 functions as a negative regulator of insulin resistance, hepatic steatosis, and associated inflammatory responses, which depends on its inhibitory regulation of ASK1 activity. LAY SUMMARY: DKK3 expression is decreased in the non-alcoholic fatty liver of humans and mice. Adding DKK3 expression alleviates fatty liver in mice by inhibiting ASK1 activity.


Assuntos
Hepatopatia Gordurosa não Alcoólica , Obesidade , Animais , Dieta Hiperlipídica , Hepatócitos , Humanos , Resistência à Insulina , Fígado , MAP Quinase Quinase Quinase 5 , Camundongos , Camundongos Endogâmicos C57BL
9.
Hypertension ; 67(5): 866-77, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27021007

RESUMO

The calcium-responsive molecule, calcineurin, has been well characterized to play a causal role in pathological cardiac hypertrophy over the past decade. However, the intrinsic negative regulation of calcineurin signaling during the progression of cardiomyocyte hypertrophy remains enigmatic. Herein, we explored the role of EPI64C, a dual inhibitor of both Ras and calcineurin signaling during T-cell activation, in pressure overload-induced cardiac hypertrophy. We generated a cardiac-specific Epi64c conditional knockout mouse strain and showed that loss of Epi64c remarkably exacerbates pressure overload-induced cardiac hypertrophy. In contrast, EPI64C gain-of-function in cardiomyocyte-specific Epi64c transgenic mice exerts potent protective effects against cardiac hypertrophy. Mechanistically, the cardioprotective effects of EPI64C are largely attributed to the disrupted calcineurin signaling but are independent of its Ras suppressive capability. Molecular studies have indicated that the 406 to 446 C-terminal amino acids in EPI64C directly bind to the 287 to 337 amino acids in the catalytic domain of calcineurin, which is responsible for the EPI64C-mediated suppressive effects. We further extrapolated our studies to cynomolgus monkeys and showed that gene therapy based on lentivirus-mediated EPI64C overexpression in the monkey hearts blunted pressure overload-induced cardiac hypertrophy. Our study thus identified EPI64C as a novel negative regulator in cardiac hypertrophy by targeting calcineurin signaling and demonstrated the potential of gene therapy and drug development for treating cardiac hypertrophy.


Assuntos
Angiotensina II/farmacologia , Calcineurina/metabolismo , Débito Cardíaco Elevado , Cardiomegalia/prevenção & controle , Proteínas Ativadoras de GTPase/metabolismo , Animais , Western Blotting , Cardiomegalia/metabolismo , Cardiomegalia/fisiopatologia , Modelos Animais de Doenças , Haplorrinos , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Miócitos Cardíacos/metabolismo , Pressão , Distribuição Aleatória , Recuperação de Função Fisiológica , Medição de Risco , Sensibilidade e Especificidade , Transdução de Sinais/fisiologia
10.
Nat Commun ; 7: 10592, 2016 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-26882989

RESUMO

Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, insulin resistance and a systemic pro-inflammatory response. Here we show that tumour necrosis factor receptor-associated factor 3 (TRAF3) is upregulated in mouse and human livers with hepatic steatosis. After 24 weeks on a high-fat diet (HFD), obesity, insulin resistance, hepatic steatosis and inflammatory responses are significantly ameliorated in liver-specific TRAF3-knockout mice, but exacerbated in transgenic mice overexpressing TRAF3 in hepatocytes. The detrimental effects of TRAF3 on hepatic steatosis and related pathologies are confirmed in ob/ob mice. We further show that in response to HFD, hepatocyte TRAF3 binds to TGF-ß-activated kinase 1 (TAK1) to induce TAK1 ubiquitination and subsequent autophosphorylation, thereby enhancing the activation of downstream IKKß-NF-κB and MKK-JNK-IRS1(307) signalling cascades, while disrupting AKT-GSK3ß/FOXO1 signalling. The TRAF3-TAK1 interaction and TAK1 ubiquitination are indispensable for TRAF3-regulated hepatic steatosis. In conclusion, hepatocyte TRAF3 promotes HFD-induced or genetic hepatic steatosis in a TAK1-dependent manner.


Assuntos
Fígado Gorduroso/metabolismo , Hepatócitos/metabolismo , Resistência à Insulina , MAP Quinase Quinase Quinases/metabolismo , Fator 3 Associado a Receptor de TNF/metabolismo , Animais , Fígado Gorduroso/genética , Feminino , Humanos , Fígado/metabolismo , MAP Quinase Quinase Quinases/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ligação Proteica , Transdução de Sinais , Fator 3 Associado a Receptor de TNF/genética
11.
J Hepatol ; 64(1): 146-59, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26334576

RESUMO

BACKGROUND & AIMS: The hallmarks of hepatic ischemia/reperfusion (I/R) injury, a common clinical problem that occurs during liver surgical procedures, include severe cell death and inflammatory responses that contribute to early graft failure and a higher incidence of organ rejection. Unfortunately, effective therapeutic strategies are limited. Tumor necrosis factor receptor (TNFR)-associated factor (TRAF) 3 transduces apoptosis and/or inflammation-related signaling pathways to regulate cell survival and cytokine production. However, the role of TRAF3 in hepatic I/R-induced liver damage remains unknown. METHODS: Hepatocyte- or myeloid cell-specific TRAF3 knockdown or transgenic mice were subjected to an I/R model in vivo, and in vitro experiments were performed by treating primary hepatocytes from these mice with hypoxia/reoxygenation stimulation. The function of TRAF3 in I/R-induced liver damage and the potential underlying mechanisms were investigated through various phenotypic analyses and biological approaches. RESULTS: Hepatocyte-specific, but not myeloid cell-specific, TRAF3 deficiency reduced cell death, inflammatory cell infiltration, and cytokine production in both in vivo and in vitro hepatic I/R models, whereas hepatic TRAF3 overexpression resulted in the opposite effects. Mechanistically, TRAF3 directly binds to TAK1, which enhances the activation of the downstream NF-κB and JNK pathways. Importantly, inhibition of TAK1 almost completely reversed the TRAF3 overexpression-mediated exacerbation of I/R injury. CONCLUSIONS: TRAF3 is a novel hepatic I/R mediator that promotes liver damage and inflammation via TAK1-dependent activation of the JNK and NF-κB pathways. Inhibition of hepatic TRAF3 may represent a promising approach to protect the liver against I/R injury-related diseases.


Assuntos
Fígado/irrigação sanguínea , Traumatismo por Reperfusão/etiologia , Fator 3 Associado a Receptor de TNF/fisiologia , Animais , Feminino , Humanos , MAP Quinase Quinase Quinases/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/fisiologia , Traumatismo por Reperfusão/prevenção & controle
12.
Nucleic Acids Res ; 44(6): 2613-27, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-26615201

RESUMO

The Hox genes encode transcription factors that determine embryonic pattern formation. In embryonic stem cells, the Hox genes are silenced by PRC2. Recent studies have reported a role for long noncoding RNAs in PRC2 recruitment in vertebrates. However, little is known about how PRC2 is recruited to the Hox genes in ESCs. Here, we used stable knockdown and knockout strategies to characterize the function of the long noncoding RNAGm15055 in the regulation of Hoxa genes in mouse ESCs. We found that Gm15055 is highly expressed in mESCs and its expression is maintained by OCT4.Gm15055 represses Hoxa gene expression by recruiting PRC2 to the cluster and maintaining the H3K27me3 modification on Hoxa promoters. A chromosome conformation capture assay revealed the close physical association of the Gm15055 locus to multiple sites at the Hoxa gene cluster in mESCs, which may facilitate the in cis targeting of Gm15055RNA to the Hoxa genes. Furthermore, an OCT4-responsive positive cis-regulatory element is found in the Gm15055 gene locus, which potentially regulates both Gm15055 itself and the Hoxa gene activation. This study suggests how PRC2 is recruited to the Hoxa locus in mESCs, and implies an elaborate mechanism for Hoxa gene regulation in mESCs.


Assuntos
Proteínas de Homeodomínio/genética , Células-Tronco Embrionárias Murinas/metabolismo , Família Multigênica , Fator 3 de Transcrição de Octâmero/genética , Complexo Repressor Polycomb 2/genética , RNA Longo não Codificante/genética , Animais , Linhagem Celular , Cromatina/química , Cromatina/metabolismo , Regulação da Expressão Gênica , Histonas/genética , Histonas/metabolismo , Proteínas de Homeodomínio/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas/citologia , Fator 3 de Transcrição de Octâmero/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Regiões Promotoras Genéticas , RNA Longo não Codificante/antagonistas & inibidores , RNA Longo não Codificante/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais
13.
Hypertension ; 66(3): 604-16, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26269654

RESUMO

Neuronal death after ischemic stroke involves multiple pathophysiological events, as well as a complex molecular mechanism. Inhibiting a single therapeutic target that is involved in several ischemic signaling cascades may be a promising strategy for stroke management. Here, we report the versatile biological roles of tumor necrosis factor receptor-associated factor 3 (TRAF3) in ischemic stroke. Using several genetically manipulated mouse strains, we also demonstrated that TRAF3 inhibition can be neuroprotective. TRAF3 expression, which is robustly induced in response to ischemia/reperfusion (I/R) injury, was detected in neurons. Overexpression of TRAF3 in neurons led to aggravated neuronal loss and enlarged infarcts; these effects were reversed in TRAF3-knockout mice. Neuronal TRAF3 also contributed to c-Jun kinase-, nuclear factor κB- and Rac-1-induced neuronal death, inflammation, and oxidative stress. Mechanistically, we showed that TRAF3 interacts with transforming growth factor-ß-activated kinase 1 (TAK1) and potentiates phosphorylation and activation of TAK1. Phosphorylated TAK1 sequentially initiated activation of nuclear factor κB, Rac-1/NADPH oxidase, and c-Jun kinase/c-Jun signaling cascades. Using a combination of adenoviruses encoding dominant-negative TAK1 and the TAK1 inhibitor 5Z-7-oxozeaenol, we demonstrated that the TRAF3-mediated activation of ischemic cascades was TAK1-dependent. More importantly, the adverse phenotypes observed in TRAF3-overexpressing mice were completely reversed when the TRAF3-TAK1 interaction was prevented. Therefore, we have shown that TRAF3 is a central regulator of ischemic pathways, including nuclear factor κB, Rac-1, and c-Jun kinase signaling, via its interaction with and activation of TAK1. Furthermore, certain components of the TRAF3-TAK1 signaling pathway are potentially promising therapeutic targets in ischemic stroke.


Assuntos
Isquemia Encefálica/metabolismo , Morte Celular/fisiologia , Neurônios/metabolismo , Acidente Vascular Cerebral/metabolismo , Fator 3 Associado a Receptor de TNF/metabolismo , Animais , Isquemia Encefálica/patologia , MAP Quinase Quinase Quinases/genética , MAP Quinase Quinase Quinases/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , NF-kappa B/metabolismo , Neurônios/patologia , Transdução de Sinais/fisiologia , Acidente Vascular Cerebral/patologia , Fator 3 Associado a Receptor de TNF/genética , Regulação para Cima
14.
J Neurosci ; 35(34): 12047-62, 2015 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-26311783

RESUMO

UNLABELLED: Cell-surface receptors provide potential targets for the translation of bench-side findings into therapeutic strategies; however, this approach for the treatment of stroke is disappointing, at least partially due to an incomplete understanding of the targeted factors. Previous studies of oncostatin M (OSM), a member of the gp130 cytokine family, have been limited, as mouse models alone may not strongly resemble the human condition enough. In addition, the precise function of OSM in the CNS remains unclear. Here, we report that human OSM is neuroprotective in vivo and in vitro by recruiting OSMRß in the setting of ischemic stroke. Using gain- and loss-of-function approaches, we demonstrated that decreased neuronal OSMRß expression results in deteriorated stroke outcomes but that OSMRß overexpression in neurons is cerebroprotective. Moreover, administering recombinant human OSM to mice before the onset of I/R showed that human OSM can be protective in rodent models of ischemic stroke. Mechanistically, OSM/OSMRß activate the JAK2/STAT3 prosurvival signaling pathway. Collectively, these data support that human OSM may represent a promising drug candidate for stroke treatment. SIGNIFICANCE STATEMENT: OSM, a member of the gp130 cytokine family, regulates neuronal function and survival. OSM engages a second receptor, either LIFRα or OSMRß, before recruiting gp130. However, it is not clear whether OSM/OSMRß signaling is involved in neuroprotection in the setting of ischemic stroke. Recent studies show that, compared with mouse disease models, the OSM receptor system in rats more closely resembles that in humans. In the present study, we use genetic manipulations of OSMRß in both mouse and rat stroke models to demonstrate that OSMRß in neurons is critical for neuronal survival during cerebral ischemic/reperfusion. Interestingly, administration of human OSM also leads to improved stroke outcomes. Therefore, OSM may represent a promising drug candidate for stroke treatment.


Assuntos
Isquemia Encefálica/metabolismo , Isquemia Encefálica/prevenção & controle , Subunidade beta de Receptor de Oncostatina M/biossíntese , Oncostatina M/biossíntese , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/prevenção & controle , Animais , Isquemia Encefálica/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Gravidez , Ratos , Ratos Sprague-Dawley , Acidente Vascular Cerebral/patologia
15.
Hypertension ; 66(2): 356-67, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26034202

RESUMO

Cardiac hypertrophy, a common early symptom of heart failure, is regulated by numerous signaling pathways. Here, we identified tumor necrosis factor receptor-associated factor 3 (TRAF3), an adaptor protein in tumor necrosis factor-related signaling cascades, as a key regulator of cardiac hypertrophy in response to pressure overload. TRAF3 expression was upregulated in hypertrophied mice hearts and failing human hearts. Four weeks after aortic banding, cardiac-specific conditional TRAF3-knockout mice exhibited significantly reduced cardiac hypertrophy, fibrosis, and dysfunction. Conversely, transgenic mice overexpressing TRAF3 in the heart developed exaggerated cardiac hypertrophy in response to pressure overload. TRAF3 also promoted an angiotensin II- or phenylephrine-induced hypertrophic response in isolated cardiomyocytes. Mechanistically, TRAF3 directly bound to TANK-binding kinase 1 (TBK1), causing increased TBK1 phosphorylation in response to hypertrophic stimuli. This interaction between TRAF3 and TBK1 further activated AKT signaling, which ultimately promoted the development of cardiac hypertrophy. Our findings not only reveal a key role of TRAF3 in regulating the hypertrophic response but also uncover TRAF3-TBK1-AKT as a novel signaling pathway in the development of cardiac hypertrophy and heart failure. This pathway may represent a potential therapeutic target for this pathological process.


Assuntos
Cardiomegalia/patologia , Cardiomegalia/fisiopatologia , Transdução de Sinais/fisiologia , Fator 3 Associado a Receptor de TNF/fisiologia , Regulação para Cima/fisiologia , Angiotensina II/farmacologia , Animais , Modelos Animais de Doenças , Feminino , Humanos , Hipertrofia , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Fenilefrina/farmacologia , Fosforilação/fisiologia , Proteínas Serina-Treonina Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Fator 3 Associado a Receptor de TNF/deficiência , Fator 3 Associado a Receptor de TNF/genética
16.
Hypertension ; 66(3): 571-81, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26101343

RESUMO

The adaptor protein Src homology 2-B3 (SH2B3), which belongs to a subfamily of Src homology 2 proteins, is a broad inhibitor of growth factors and cytokine signaling in hematopoietic cells. However, the role of SH2B3 in nonhematopoietic systems, particularly cardiomyocytes, has not been defined. In this study, we observed noticeable increase in SH2B3 protein expression during pathological cardiac remodeling in both humans and rodents. Follow-up in vitro gain- and loss-of-function studies suggested that SH2B3 promotes the cardiomyocyte hypertrophy response. Consistent with the cell phenotype, SH2B3 knockout (SH2B3(-/-)) mice exhibited attenuated cardiac remodeling with preserved cardiac function after chronic pressure overload. Conversely, cardiac-specific SH2B3 overexpression aggravated pressure overload-triggered cardiac hypertrophy, fibrosis, and dysfunction. Mechanistically, SH2B3 accelerates and exacerbates cardiac remodeling through the activation of focal adhesion kinase, which, in turn, activates the prohypertrophic downstream phosphoinositide 3-kinase-AKT-mammalian target of rapamycin/glycogen synthase kinase 3ß signaling pathway. Finally, we generated a novel SH2B3 knockout rat line and further confirmed the protective effects of SH2B3 deficiency on cardiac remodeling across species. Collectively, our data indicate that SH2B3 functions as a novel and effective modulator of cardiac remodeling and failure.


Assuntos
Pressão Sanguínea/fisiologia , Cardiomegalia/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Animais , Cardiomegalia/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana , Camundongos , Camundongos Knockout , Ratos , Transdução de Sinais/fisiologia
17.
Biochim Biophys Acta ; 1852(2): 365-78, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24807060

RESUMO

The interferon-regulatory factor (IRF) family comprises nine members in mammals. Although this transcription factor family was originally thought to function primarily in the immune system, contributing to both the innate immune response and the development of immune cells, recent advances have revealed that IRFs plays critical roles in other biological processes, such as metabolism. Accordingly, abnormalities in the expression and/or function of IRFs have increasingly been linked to disease. Herein, we provide an update on the recent progress regarding the regulation of immune responses and immune cell development associated with IRFs. Additionally, we discuss the relationships between IRFs and immunity, metabolism, and disease, with a particular focus on the role of IRFs as stress sensors. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.


Assuntos
Doença , Imunidade , Fatores Reguladores de Interferon/metabolismo , Metabolismo , Animais , Humanos , Imunidade Inata , Modelos Biológicos
18.
Mol Cell Biol ; 34(20): 3867-79, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25135475

RESUMO

HOX cluster genes are activated sequentially in their positional order along the chromosome during vertebrate development. This phenomenon, known as temporal colinearity, depends on transcriptional silencing of 5' HOX genes. Chromatin looping was recently identified as a conserved feature of silent HOX clusters, with CCCTC-binding factor (CTCF) binding sites located at the loop bases. However, the potential contribution of CTCF to HOX cluster silencing and the underlying mechanism have not been established. Here, we demonstrate that the HOXA locus is organized by CTCF into chromatin loops and that CTCF depletion causes significantly enhanced activation of HOXA3 to -A7, -A9 to -A11, and -A13 in response to retinoic acid, with the highest effect observed for HOXA9. Our subsequent analyses revealed that CTCF facilitates the stabilization of Polycomb repressive complex 2 (PRC2) and trimethylated lysine 27 of histone H3 (H3K27me3) at the human HOXA locus. Our results reveal that CTCF functions as a controller of HOXA cluster silencing and mediates PRC2-repressive higher-order chromatin structure.


Assuntos
Cromatina/genética , Inativação Gênica , Proteínas de Homeodomínio/genética , Complexo Repressor Polycomb 2/fisiologia , Proteínas Repressoras/fisiologia , Sequência de Bases , Fator de Ligação a CCCTC , Linhagem Celular Tumoral , Cromatina/metabolismo , Loci Gênicos , Histonas/metabolismo , Proteínas de Homeodomínio/metabolismo , Proteínas de Homeodomínio/ultraestrutura , Humanos , Conformação Molecular , Estabilidade Proteica , Deleção de Sequência , Tretinoína/fisiologia
19.
J Biol Chem ; 287(36): 30641-52, 2012 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-22825848

RESUMO

Matrix attachment region (MAR)-binding protein (MARBP) has profound influence on gene transcriptional control by tethering genes to the nuclear scaffold. MARBP SATB2 is recently known as a versatile regulator functioning in the differentiation of multiple cell types including embryonic stem cells, osteoblasts and immunocytes. Roles of SATB2 in erythroid cells and its working mechanism in orchestrating target gene expression are largely unexplored. We show here that SATB2 is expressed in erythroid cells and activates γ-globin genes by binding to MARs in their promoters and recruiting histone acetylase PCAF. Further analysis in higher-order chromatin structure shows that SATB2 affects physical proximity of human (G)γ- and (A)γ-globin promoters via self-association. We also found that SATB2 interacts with SATB1, which specifically activates ε-globin gene expression. Our results establish SATB2 as a novel γ-globin gene regulator and provide a glimpse of the differential and cooperative roles of SATB family proteins in modulating clustered genes transcription and mediating higher-order chromatin structures.


Assuntos
Células Eritroides/metabolismo , Regulação da Expressão Gênica/fisiologia , Proteínas de Ligação à Região de Interação com a Matriz/metabolismo , Regiões de Interação com a Matriz/fisiologia , Família Multigênica/fisiologia , Fatores de Transcrição/metabolismo , gama-Globinas/biossíntese , Animais , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Células Eritroides/citologia , Humanos , Células K562 , Proteínas de Ligação à Região de Interação com a Matriz/genética , Camundongos , Fatores de Transcrição/genética , Transcrição Genética/fisiologia , gama-Globinas/genética
20.
Nucleic Acids Res ; 40(11): 4804-15, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22328728

RESUMO

The higher order chromatin structure has recently been revealed as a critical new layer of gene transcriptional control. Changes in higher order chromatin structures were shown to correlate with the availability of transcriptional factors and/or MAR (matrix attachment region) binding proteins, which tether genomic DNA to the nuclear matrix. How posttranslational modification to these protein organizers may affect higher order chromatin structure still pending experimental investigation. The type III histone deacetylase silent mating type information regulator 2, S. cerevisiae, homolog 1 (SIRT1) participates in many physiological processes through targeting both histone and transcriptional factors. We show that MAR binding protein SATB1, which mediates chromatin looping in cytokine, MHC-I and ß-globin gene loci, as a new type of SIRT1 substrate. SIRT1 expression increased accompanying erythroid differentiation and the strengthening of ß-globin cluster higher order chromatin structure, while knockdown of SIRT1 in erythroid k562 cells weakened the long-range interaction between two SATB1 binding sites in the ß-globin locus, MAR(HS2) and MAR(ε). We also show that SIRT1 activity significantly affects ε-globin gene expression in a SATB1-dependent manner and that knockdown of SIRT1 largely blocks ε-globin gene activation during erythroid differentiation. Our work proposes that SIRT1 orchestrates changes in higher order chromatin structure during erythropoiesis, and reveals the dynamic higher order chromatin structure regulation at posttranslational modification level.


Assuntos
Regulação da Expressão Gênica , Proteínas de Ligação à Região de Interação com a Matriz/metabolismo , Regiões de Interação com a Matriz , Sirtuína 1/metabolismo , Globinas épsilon/genética , Células Cultivadas , Células Eritroides/efeitos dos fármacos , Células Eritroides/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hemina/farmacologia , Humanos , Células K562 , Região de Controle de Locus Gênico , Globinas beta/genética , Globinas épsilon/biossíntese
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