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1.
Nature ; 585(7826): 609-613, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32939087

RESUMO

Breaks in DNA strands recruit the protein PARP1 and its paralogue PARP2 to modify histones and other substrates through the addition of mono- and poly(ADP-ribose) (PAR)1-5. In the DNA damage responses, this post-translational modification occurs predominantly on serine residues6-8 and requires HPF1, an accessory factor that switches the amino acid specificity of PARP1 and PARP2 from aspartate or glutamate to serine9,10. Poly(ADP) ribosylation (PARylation) is important for subsequent chromatin decompaction and provides an anchor for the recruitment of downstream signalling and repair factors to the sites of DNA breaks2,11. Here, to understand the molecular mechanism by which PARP enzymes recognize DNA breaks within chromatin, we determined the cryo-electron-microscopic structure of human PARP2-HPF1 bound to a nucleosome. This showed that PARP2-HPF1 bridges two nucleosomes, with the broken DNA aligned in a position suitable for ligation, revealing the initial step in the repair of double-strand DNA breaks. The bridging induces structural changes in PARP2 that signal the recognition of a DNA break to the catalytic domain, which licenses HPF1 binding and PARP2 activation. Our data suggest that active PARP2 cycles through different conformational states to exchange NAD+ and substrate, which may enable PARP enzymes to act processively while bound to chromatin. The processes of PARP activation and the PARP catalytic cycle we describe can explain mechanisms of resistance to PARP inhibitors and will aid the development of better inhibitors as cancer treatments12-16.


Assuntos
Proteínas de Transporte/metabolismo , Quebras de DNA de Cadeia Dupla , Proteínas Nucleares/metabolismo , Nucleossomos/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Biocatálise , Proteínas de Transporte/química , Proteínas de Transporte/ultraestrutura , Microscopia Crioeletrônica , DNA/metabolismo , Reparo do DNA , Ativação Enzimática , Humanos , Modelos Moleculares , NAD/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/ultraestrutura , Nucleossomos/química , Nucleossomos/ultraestrutura , Poli(ADP-Ribose) Polimerases/química , Poli(ADP-Ribose) Polimerases/ultraestrutura , Domínios Proteicos
2.
PLoS One ; 15(9): e0235824, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881898

RESUMO

Pulmonary hypertension due to left heart disease (PH-LHD) is a momentous pulmonary hypertension disease, and left heart disease is the most familiar cause. Mechanical stretching may be a crucial cause of vascular remodeling. While, the underlining mechanism of mechanical stretching-induced in remodeling of pulmonary vein in the early stage of PH-LHD has not been completely elucidated. In our study, the PH-LHD model rats were successfully constructed. After 25 days, doppler echocardiography and hemodynamic examination were performed. In addition, after treatment, the levels of matrix metalloproteinase-9 (MMP-9) and transforming growth factor-ß1 (TGF-ß1) were determined by ELISA, immunohistochemistry and western blot assays in the pulmonary veins. Moreover, the pathological change of pulmonary tissues was evaluated by H&E staining. Our results uncovered that left ventricular insufficiency and interventricular septal shift could be observed in PH-LHD model rats, and the right ventricular systolic pressure (RVSP) and mean left atrial pressure (mLAP) were also elevated in PH-LHD model rats. Meanwhile, we found that MMP-9 and TGF-ß1 could be highly expressed in PH-LHD model rats. Besides, we revealed that stretch-activated channel (SAC)/mitogen-activated protein kinases (MAPKs) signaling pathway could be involved in the upregulations of MMP-9 and TGF-ß1 mediated by mechanical stretching in pulmonary vein. Therefore, current research revealed that mechanical stretching induced the increasing expressions of MMP-9 and TGF-ß1 in pulmonary vein, which could be mediated by activation of SAC/MAPKs signaling pathway in the early stage of PH-LHD.


Assuntos
Hipertensão Pulmonar/fisiopatologia , Sistema de Sinalização das MAP Quinases , Metaloproteinase 9 da Matriz/metabolismo , Veias Pulmonares/fisiopatologia , Fator de Crescimento Transformador beta1/metabolismo , Disfunção Ventricular Esquerda/fisiopatologia , Animais , Fenômenos Biomecânicos , Modelos Animais de Doenças , Ativação Enzimática , Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/metabolismo , Masculino , Veias Pulmonares/metabolismo , Ratos , Ratos Sprague-Dawley , Estresse Mecânico , Remodelação Vascular , Disfunção Ventricular Esquerda/complicações , Disfunção Ventricular Esquerda/metabolismo
3.
PLoS One ; 15(9): e0235960, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986718

RESUMO

OBJECTIVE: To investigate the effects of AMPK activation on mitochondrial inhibition by uremic serum through the AMPK-activated rat peritoneal macrophages stimulated by uremic serum, thereby providing a reference for the clinical treatment of chronic kidney disease. METHODS: Twenty-two male Sprague-Dawley (SD) rats were included as experimental subjects. Fifteen rats were constructed into chronic kidney disease models (the model group). The remaining seven rats only received renal capsule stripping instead of nephrectomy (the sham-operated group). Ten weeks after model construction, the bodyweight, blood biochemical indicators, and metabolic parameters of rats in groups were measured. Meanwhile, the expression of the M1 phenotype marker protein in peritoneal macrophages was determined. RESULTS: Ten weeks after model construction, the bodyweight of rats in the model group was significantly lower than that in the sham-operated group. The values of urea nitrogen and serum creatinine were significantly higher than those in the sham-operated group (P<0.01). The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and the monocyte chemoattractant protein 1 (MCP-1) of rats in the model group were significantly higher than those in the sham-operated group (P <0.01). After the lipopolysaccharide (LPS) stimulation, the expressions of M1 phenotype marker mRNA in the model group was significantly increased. The expression of mitochondrial structural protein mRNA in the peritoneal macrophages of rats in the model group was significantly lower than that in the sham-operated group. The expression of M1 phenotype marker mRNA was significantly decreased in the uremic serum group after AMPK agonist (P<0.01). CONCLUSION: In rats with chronic renal insufficiency, mitochondrial regeneration was dysfunctional in macrophages. By activating AMPK, the inhibitory effect of uremia serum on mitochondrial regeneration of macrophages was improved. Therefore, AMPK was a critical factor that could regulate mitochondrial regeneration of macrophages.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Ativação Enzimática , Macrófagos Peritoneais/metabolismo , Mitocôndrias/metabolismo , Uremia/metabolismo , Animais , Macrófagos Peritoneais/patologia , Masculino , Mitocôndrias/patologia , Dinâmica Mitocondrial , RNA Mensageiro/metabolismo , RNA Mitocondrial/metabolismo , Ratos , Ratos Sprague-Dawley , Uremia/sangue , Uremia/patologia
4.
PLoS Biol ; 18(9): e3000866, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32881857

RESUMO

The small GTPase RhoA is a central signaling enzyme that is involved in various cellular processes such as cytoskeletal dynamics, transcription, and cell cycle progression. Many signal transduction pathways activate RhoA-for instance, Gαq-coupled Histamine 1 Receptor signaling via Gαq-dependent activation of RhoGEFs such as p63. Although multiple upstream regulators of RhoA have been identified, the temporal regulation of RhoA and the coordination of different upstream components in its regulation have not been well characterized. In this study, live-cell measurement of RhoA activation revealed a biphasic increase of RhoA activity upon histamine stimulation. We showed that the first and second phase of RhoA activity are dependent on p63 and Ca2+/PKC, respectively, and further identified phosphorylation of serine 240 on p115 RhoGEF by PKC to be the mechanistic link between PKC and RhoA. Combined approaches of computational modeling and quantitative measurement revealed that the second phase of RhoA activation is insensitive to rapid turning off of the receptor and is required for maintaining RhoA-mediated transcription after the termination of the receptor signaling. Thus, two divergent pathways enable both rapid activation and persistent signaling in receptor-mediated RhoA signaling via intricate temporal regulation.


Assuntos
Histamina/farmacologia , Proteína rhoA de Ligação ao GTP/metabolismo , Animais , Sinalização do Cálcio/efeitos dos fármacos , Células Cultivadas , Ativação Enzimática/efeitos dos fármacos , Células HeLa , Humanos , Camundongos , Fosforilação/efeitos dos fármacos , Proteína Quinase C/metabolismo , Receptores Histamínicos/metabolismo , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Transdução de Sinais/efeitos dos fármacos
5.
Nat Commun ; 11(1): 4480, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32900992

RESUMO

Macroautophagy initiates by formation of isolation membranes, but the source of phospholipids for the membrane biogenesis remains elusive. Here, we show that autophagic membranes incorporate newly synthesized phosphatidylcholine, and that CTP:phosphocholine cytidylyltransferase ß3 (CCTß3), an isoform of the rate-limiting enzyme in the Kennedy pathway, plays an essential role. In starved mouse embryo fibroblasts, CCTß3 is initially recruited to autophagic membranes, but upon prolonged starvation, it concentrates on lipid droplets that are generated from autophagic degradation products. Omegasomes and isolation membranes emanate from around those lipid droplets. Autophagy in prolonged starvation is suppressed by knockdown of CCTß3 and is enhanced by its overexpression. This CCTß3-dependent mechanism is also present in U2OS, an osteosarcoma cell line, and autophagy and cell survival in starvation are decreased by CCTß3 depletion. The results demonstrate that phosphatidylcholine synthesis through CCTß3 activation on lipid droplets is crucial for sustaining autophagy and long-term cell survival.


Assuntos
Autofagia/fisiologia , Colina-Fosfato Citidililtransferase/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Animais , Autofagossomos/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular , Colina-Fosfato Citidililtransferase/antagonistas & inibidores , Colina-Fosfato Citidililtransferase/genética , Meios de Cultura , Ativação Enzimática , Técnicas de Silenciamento de Genes , Humanos , Gotículas Lipídicas/metabolismo , Camundongos , Modelos Biológicos , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Osteossarcoma/metabolismo , Osteossarcoma/patologia , Fosfatidilcolinas/metabolismo
6.
Nat Commun ; 11(1): 4596, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32929083

RESUMO

Earlier studies indicate that either the canonical or non-canonical pathways of inflammasome activation have a limited role on malaria pathogenesis. Here, we report that caspase-8 is a central mediator of systemic inflammation, septic shock in the Plasmodium chabaudi-infected mice and the P. berghei-induced experimental cerebral malaria (ECM). Importantly, our results indicate that the combined deficiencies of caspases-8/1/11 or caspase-8/gasdermin-D (GSDM-D) renders mice impaired to produce both TNFα and IL-1ß and highly resistant to lethality in these models, disclosing a complementary, but independent role of caspase-8 and caspases-1/11/GSDM-D in the pathogenesis of malaria. Further, we find that monocytes from malaria patients express active caspases-1, -4 and -8 suggesting that these inflammatory caspases may also play a role in the pathogenesis of human disease.


Assuntos
Caspase 8/metabolismo , Inflamação/patologia , Malária Cerebral/enzimologia , Animais , Encéfalo/patologia , Caspase 1/metabolismo , Células Dendríticas/metabolismo , Ativação Enzimática , Matriz Extracelular/metabolismo , Regulação da Expressão Gênica , Humanos , Interferon gama/metabolismo , Interleucina-1beta/metabolismo , Lipopolissacarídeos , Malária Cerebral/genética , Camundongos Endogâmicos C57BL , Monócitos/metabolismo , Plasmodium chabaudi/fisiologia , Baço/metabolismo , Receptores Toll-Like/metabolismo
7.
Sheng Wu Gong Cheng Xue Bao ; 36(8): 1568-1577, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32924355

RESUMO

Catalase catalyzes the decomposition of H2O2 to H2O and O2, and has a wide range of industrial applications. However, most catalases used in the textile and paper industries are often subjected to high-alkaline challenges which makes it necessary to develop alkaline catalase. In this study, a catalase from Corynebacterium glutamicum was expressed in Escherichia coli, and the expression conditions were optimized. The recombinant catalase was purified by Ni-chelating affinity chromatography, and the recombinant enzyme was characterized. The optimal conditions of producing the recombinant catalase were: an IPTG concentration of 0.2 mmol/L, a culturing temperature of 25 °C and a culturing time of 11 h. The purified catalase had a specific activity of 55 266 U/mg, and it had a high activity in the pH range of 4.0 to11.5, with the highest activity at pH 11.0. When treated in pH 11.0 for 3 h, the enzyme retained 93% of its activity, indicating that the enzyme was qualified with a favorable stability under high-alkaline condition. The recombinant catalase had maximal activity at 30 °C, and showed a satisfactory thermal stability at a range of 25 °C to 50 °C. The apparent Km and Vmax values of purified catalase were 25.89 mmol/L and 185.18 mmol/(minmg), respectively. Besides, different inhibitors, such as sodium dodecyl sulfate (SDS), urea, NaN2, ß-mercaptoethanol, and EDTA had different degrees of inhibition on enzyme activity. The catalase from C. glutamicum shows high catalytic efficiency and high alkaline stability, suggesting its potential utilization in industrial production.


Assuntos
Catalase , Corynebacterium glutamicum , Regulação Enzimológica da Expressão Gênica , Catalase/genética , Catalase/isolamento & purificação , Catalase/metabolismo , Corynebacterium glutamicum/enzimologia , Ativação Enzimática , Estabilidade Enzimática , Concentração de Íons de Hidrogênio
8.
Sheng Wu Gong Cheng Xue Bao ; 36(8): 1578-1589, 2020 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-32924356

RESUMO

As self-subunit swapping chaperones or metallochaperones, the activators assist nitrile hydratases to take up metal ions and they are essential for active expression of nitrile hydratases. Compared with nitrile hydratases, the activators have a low sequence identity. Study of the activation characteristics and the relationships between structures and functions of the activators is of great significance for understanding the maturation mechanism of nitrile hydratase. We co-expressed low-molecular-mass nitrile hydratase (L-NHase) from Rhodococcus rhodochrous J1 with four heterologous activators respectively and determined their activation abilities. Then we made sequence analysis and structure modelling, and studied the functions of the important domains of the activators. Results showed that all four heterologous activators could activate L-NHase, however, the specific activities of L-NHases were different after activation. L-NHase showed the highest specific activity after being activated by activator A, which was 97.79% of that of the original enzyme, but the specific activity of L-NHase after being activated by activator G was only 23.94% of that of the original enzyme. Activator E and activator G had conserved domains (TIGR03889), and deletion of their partial sequences resulted in a substantial loss of activation abilities for both activators. Replacing the N-terminal sequence of activator G with the N-terminal sequence of activator E, and adding the C-terminal sequence of activator E to the C-terminus of activator G could increase the specific activity of L-NHase by 178.40%. The activation by nitrile hydratase activators was universal and specific, and the conserved domains of activators were critical for activation, while the N-terminal domain and C-terminal domain also had important effects on activation.


Assuntos
Hidroliases , Rhodococcus , Ativação Enzimática , Hidroliases/genética , Hidroliases/metabolismo , Peso Molecular , Rhodococcus/enzimologia , Rhodococcus/genética
9.
Nat Commun ; 11(1): 4029, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32788597

RESUMO

In autosomal dominant optic atrophy (ADOA), caused by mutations in the mitochondrial cristae biogenesis and fusion protein optic atrophy 1 (Opa1), retinal ganglion cell (RGC) dysfunction and visual loss occur by unknown mechanisms. Here, we show a role for autophagy in ADOA pathogenesis. In RGCs expressing mutated Opa1, active 5' AMP-activated protein kinase (AMPK) and its autophagy effector ULK1 accumulate at axonal hillocks. This AMPK activation triggers localized hillock autophagosome accumulation and mitophagy, ultimately resulting in reduced axonal mitochondrial content that is restored by genetic inhibition of AMPK and autophagy. In C. elegans, deletion of AMPK or of key autophagy and mitophagy genes normalizes the axonal mitochondrial content that is reduced upon mitochondrial dysfunction. In conditional, RGC specific Opa1-deficient mice, depletion of the essential autophagy gene Atg7 normalizes the excess autophagy and corrects the visual defects caused by Opa1 ablation. Thus, our data identify AMPK and autophagy as targetable components of ADOA pathogenesis.


Assuntos
Autofagia , Atrofia Óptica Autossômica Dominante/complicações , Transtornos da Visão/complicações , Adenilato Quinase/metabolismo , Animais , Autofagia/genética , Axônios/patologia , Caenorhabditis elegans/metabolismo , Modelos Animais de Doenças , Ativação Enzimática , GTP Fosfo-Hidrolases/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismo , Mitofagia , Mutação/genética , Fosforilação , Células Ganglionares da Retina/patologia
10.
Science ; 369(6503)2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32732395

RESUMO

Family B heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) play important roles in carbohydrate metabolism. Recent structures of family B GPCR-Gs protein complexes reveal a disruption in the α-helix of transmembrane segment 6 (TM6) not observed in family A GPCRs. To investigate the functional impact of this structural difference, we compared the structure and function of the glucagon receptor (GCGR; family B) with the ß2 adrenergic receptor (ß2AR; family A). We determined the structure of the GCGR-Gs complex by means of cryo-electron microscopy at 3.1-angstrom resolution. This structure shows the distinct break in TM6. Guanosine triphosphate (GTP) turnover, guanosine diphosphate release, GTP binding, and G protein dissociation studies revealed much slower rates for G protein activation by the GCGR compared with the ß2AR. Fluorescence and double electron-electron resonance studies suggest that this difference is due to the inability of agonist alone to induce a detectable outward movement of the cytoplasmic end of TM6.


Assuntos
Subunidades alfa Gs de Proteínas de Ligação ao GTP/química , Receptores Adrenérgicos beta 2/química , Receptores de Glucagon/química , Microscopia Crioeletrônica , Ativação Enzimática , Humanos , Estrutura Secundária de Proteína
11.
Am J Med Sci ; 360(3): 279-286, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32829780

RESUMO

BACKGROUND: The essential role of 6-phosphogluconate dehydrogenase (6PGD), the enzyme catalyzing the oxidative pentose phosphate pathway, in tumor growth and metabolism has garnered attention in recent years. In this work, we are the first to demonstrate that aberrant activation of 6PGD is a feature in renal cell carcinoma (RCC) and is critically involved in renal carcinogenesis and chemo- and immuno-resistance. MATERIALS AND METHODS: 6PGD expression and activity were systematically analyzed in normal and malignant renal cells and tissues. The roles of 6PGD and its downstream mechanism were investigated using gain-of-function and loss-of-function approaches. RESULTS: 6PGD expression and enzyme activity were increased in RCC cells and patients' samples. Activation of 6PGD via gain-of-function approach promoted growth of normal kidney but not RCC cells, and alleviated the efficacy of chemotherapeutic (e.g., 5-FU) and immunotherapeutic (e.g., IFN-α) agents. In contrast, 6PGD inhibition using siRNA knockdown and pharmacological inhibitor physcion augmented the inhibitory effects of 5-FU and IFN-α in RCC. Mechanistic studies demonstrated that 6PGD inhibition activated AMPK signaling, leading to ACC1 enzyme inhibition and reduction of lipid synthesis. In addition, 6PGD inhibition disrupted NADPH and NADH homeostasis in RCC cells as shown by the decreased level of NADPH and NADH, and suppressed SIRT-1 activity. AMPK inhibition by siRNA knockdown reversed the inhibitory effects of physcion, demonstrating that the effect of 6PGD inhibition is AMPK activation dependent. CONCLUSIONS: Our work provides preclinical evidence that 6PGD inhibition may represent a potential therapeutic strategy to augment the efficacy of RCC standard of care drugs.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Carcinoma de Células Renais/terapia , Reprogramação Celular/fisiologia , Neoplasias Renais/terapia , Fosfogluconato Desidrogenase/metabolismo , Transdução de Sinais/fisiologia , Proteínas Quinases Ativadas por AMP/genética , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/patologia , Linhagem Celular , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/fisiologia , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Fluoruracila/uso terapêutico , Técnicas de Silenciamento de Genes , Humanos , Imunoterapia , Interferon-alfa/uso terapêutico , Rim/patologia , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/patologia , NADP/fisiologia , Fosfogluconato Desidrogenase/antagonistas & inibidores , Fosfogluconato Desidrogenase/genética , RNA Interferente Pequeno , Regulação para Cima
12.
Infection ; 48(5): 665-669, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32737833

RESUMO

Novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) became pandemic by the end of March 2020. In contrast to the 2002-2003 SARS-CoV outbreak, which had a higher pathogenicity and lead to higher mortality rates, SARSCoV-2 infection appears to be much more contagious. Moreover, many SARS-CoV-2 infected patients are reported to develop low-titer neutralizing antibody and usually suffer prolonged illness, suggesting a more effective SARS-CoV-2 immune surveillance evasion than SARS-CoV. This paper summarizes the current state of art about the differences and similarities between the pathogenesis of the two coronaviruses, focusing on receptor binding domain, host cell entry and protease activation. Such differences may provide insight into possible intervention strategies to fight the pandemic.


Assuntos
Betacoronavirus/patogenicidade , Infecções por Coronavirus/epidemiologia , Pandemias , Pneumonia Viral/epidemiologia , Vírus da SARS/patogenicidade , Síndrome Respiratória Aguda Grave/epidemiologia , Glicoproteína da Espícula de Coronavírus/imunologia , Anticorpos Antivirais/biossíntese , Betacoronavirus/imunologia , Catepsinas/genética , Catepsinas/imunologia , Infecções por Coronavirus/enzimologia , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/patologia , Ativação Enzimática/imunologia , Humanos , Evasão da Resposta Imune , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/imunologia , Pneumonia Viral/enzimologia , Pneumonia Viral/imunologia , Pneumonia Viral/patologia , Ligação Proteica , Domínios Proteicos , Vírus da SARS/imunologia , Serina Endopeptidases/genética , Serina Endopeptidases/imunologia , Síndrome Respiratória Aguda Grave/enzimologia , Síndrome Respiratória Aguda Grave/imunologia , Síndrome Respiratória Aguda Grave/patologia , Índice de Gravidade de Doença , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Internalização do Vírus , Replicação Viral
13.
Med Hypotheses ; 143: 110142, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32759013

RESUMO

BACKGROUND: Pulmonary hypertension is a significant complication for some patients with COVID-19 pneumonia, especially those requiring intensive care. Tachyphylaxis to the current therapy, inhaled nitric oxide (iNO), is also common. In vitro, folic acid directly increases nitric oxide (NO) production and extends its duration of action; effects which could be of benefit in reversing pulmonary hypertension and severe hypoxaemia. Our work has shown that, in the systemic circulation, folic acid in high dose rapidly improves nitric oxide mediated vasodilation, by activating endothelial nitric oxide synthase (eNOS). HYPOTHESIS: A similar effect of high dose folic acid on pulmonary endothelial function would be expected from the same mechanism and would lead to improvement in pulmonary perfusion. We therefore hypothesise that folic acid, 5 mg or greater, is a useful therapeutic option for pulmonary hypertension and/or refractory severe hypoxaemia, in patients with severe COVID-19 associated pneumonia in whom NO therapy is considered, with a very low risk of adverse effects.


Assuntos
Betacoronavirus , Infecções por Coronavirus/complicações , Ácido Fólico/uso terapêutico , Hipertensão Pulmonar/tratamento farmacológico , Óxido Nítrico/metabolismo , Pandemias , Pneumonia Viral/complicações , Administração por Inalação , Animais , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Ativação Enzimática/efeitos dos fármacos , Ácido Fólico/administração & dosagem , Ácido Fólico/farmacologia , Humanos , Hipertensão Pulmonar/complicações , Hipóxia/tratamento farmacológico , Hipóxia/etiologia , Camundongos , Óxido Nítrico/administração & dosagem , Óxido Nítrico/uso terapêutico , Óxido Nítrico Sintase Tipo III/efeitos dos fármacos , Taquifilaxia
14.
Nat Commun ; 11(1): 3859, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737298

RESUMO

Non-enzymatic proteins including antibodies function as biomarkers and are used as biopharmaceuticals in several diseases. Protein-responsive soft materials capable of the controlled release of drugs and proteins have potential for use in next-generation diagnosis and therapies. Here, we describe a supramolecular/agarose hydrogel composite that can release a protein in response to a non-enzymatic protein. A non-enzymatic protein-responsive system is developed by hybridization of an enzyme-sensitive supramolecular hydrogel with a protein-triggered enzyme activation set. In situ imaging shows that the supramolecular/agarose hydrogel composite consists of orthogonal domains of supramolecular fibers and agarose, which play distinct roles in protein entrapment and mechanical stiffness, respectively. Integrating the enzyme activation set with the composite allows for controlled release of the embedded RNase in response to an antibody. Such composite hydrogels would be promising as a matrix embedded in a body, which can autonomously release biopharmaceuticals by sensing biomarker proteins.


Assuntos
Anidrase Carbônica II/química , Preparações de Ação Retardada/síntese química , Hidrogéis/química , Ribonucleases/química , Sefarose/química , Animais , Anticorpos/química , Avidina/química , Biotina/química , Anidrase Carbônica II/antagonistas & inibidores , Inibidores da Anidrase Carbônica/química , Bovinos , Ativação Enzimática , Transição de Fase , Reologia , Ribonucleases/antagonistas & inibidores , Sulfonamidas/química
15.
Nat Commun ; 11(1): 3841, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737323

RESUMO

Histone deacetylases (HDACs) are key enzymes in epigenetics and important drug targets in cancer biology. Whilst it has been established that HDACs regulate many cellular processes, far less is known about the regulation of these enzymes themselves. Here, we show that HDAC8 is allosterically regulated by shifts in populations between exchanging states. An inactive state is identified, which is stabilised by a range of mutations and resembles a sparsely-populated state in equilibrium with active HDAC8. Computational models show that the inactive and active states differ by small changes in a regulatory region that extends up to 28 Å from the active site. The regulatory allosteric region identified here in HDAC8 corresponds to regions in other class I HDACs known to bind regulators, thus suggesting a general mechanism. The presented results pave the way for the development of allosteric HDAC inhibitors and regulators to improve the therapy for several disease states.


Assuntos
Inibidores de Histona Desacetilases/química , Histona Desacetilases/química , Ácidos Hidroxâmicos/química , Indóis/química , Proteínas Repressoras/química , Vorinostat/química , Regulação Alostérica , Sítio Alostérico , Domínio Catalítico , Clonagem Molecular , Cristalografia por Raios X , Ativação Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Inibidores de Histona Desacetilases/metabolismo , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Ácidos Hidroxâmicos/metabolismo , Indóis/metabolismo , Simulação de Dinâmica Molecular , Mutação , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Repressoras/antagonistas & inibidores , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Especificidade por Substrato , Termodinâmica , Vorinostat/metabolismo
16.
J Immunol ; 205(6): 1564-1579, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32747502

RESUMO

Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic human coronavirus causing severe disease and mortality. MERS-CoV infection failed to elicit robust IFN response, suggesting that the virus might have evolved strategies to evade host innate immune surveillance. In this study, we identified and characterized type I IFN antagonism of MERS-CoV open reading frame (ORF) 8b accessory protein. ORF8b was abundantly expressed in MERS-CoV-infected Huh-7 cells. When ectopically expressed, ORF8b inhibited IRF3-mediated IFN-ß expression induced by Sendai virus and poly(I:C). ORF8b was found to act at a step upstream of IRF3 to impede the interaction between IRF3 kinase IKKε and chaperone protein HSP70, which is required for the activation of IKKε and IRF3. An infection study using recombinant wild-type and ORF8b-deficient MERS-CoV further confirmed the suppressive role of ORF8b in type I IFN induction and its disruption of the colocalization of HSP70 with IKKε. Ectopic expression of HSP70 relieved suppression of IFN-ß expression by ORF8b in an IKKε-dependent manner. Enhancement of IFN-ß induction in cells infected with ORF8b-deficient virus was erased when HSP70 was depleted. Taken together, HSP70 chaperone is important for IKKε activation, and MERS-CoV ORF8b suppresses type I IFN expression by competing with IKKε for interaction with HSP70.


Assuntos
Ativação Enzimática/imunologia , Quinase I-kappa B/imunologia , Interferon Tipo I/imunologia , Coronavírus da Síndrome Respiratória do Oriente Médio/imunologia , Proteínas Virais/imunologia , Betacoronavirus , Linhagem Celular , Infecções por Coronavirus , Proteínas de Choque Térmico HSP70/imunologia , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Quinase I-kappa B/metabolismo , Interferon Tipo I/metabolismo , Coronavírus da Síndrome Respiratória do Oriente Médio/metabolismo , Pandemias , Pneumonia Viral , Proteínas Virais/metabolismo
17.
PLoS Biol ; 18(6): e3000732, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32603375

RESUMO

Coordination of gene expression with nutrient availability supports proliferation and homeostasis and is shaped by protein acetylation. Yet how physiological/pathological signals link acetylation to specific gene expression programs and whether such responses are cell-type-specific is unclear. AMP-activated protein kinase (AMPK) is a key energy sensor, activated by glucose limitation to resolve nutrient supply-demand imbalances, critical for diabetes and cancer. Unexpectedly, we show here that, in gastrointestinal cancer cells, glucose activates AMPK to selectively induce EP300, but not CREB-binding protein (CBP). Consequently, EP300 is redirected away from nuclear receptors that promote differentiation towards ß-catenin, a driver of proliferation and colorectal tumorigenesis. Importantly, blocking glycogen synthesis permits reactive oxygen species (ROS) accumulation and AMPK activation in response to glucose in previously nonresponsive cells. Notably, glycogen content and activity of the ROS/AMPK/EP300/ß-catenin axis are opposite in healthy versus tumor sections. Glycogen content reduction from healthy to tumor tissue may explain AMPK switching from tumor suppressor to activator during tumor evolution.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Neoplasias Colorretais/metabolismo , Proteína p300 Associada a E1A/metabolismo , Glucose/farmacologia , Animais , Proteína de Ligação a CREB/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/patologia , Ativação Enzimática/efeitos dos fármacos , Glicogênio/metabolismo , Camundongos Endogâmicos C57BL , Ligação Proteica/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , beta Catenina/metabolismo
18.
Nature ; 585(7826): 597-602, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32612235

RESUMO

The mechanistic target of rapamycin complex 1 (mTORC1) is a key metabolic hub that controls the cellular response to environmental cues by exerting its kinase activity on multiple substrates1-3. However, whether mTORC1 responds to diverse stimuli by differentially phosphorylating specific substrates is poorly understood. Here we show that transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy4,5, is phosphorylated by mTORC1 via a substrate-specific mechanism that is mediated by Rag GTPases. Owing to this mechanism, the phosphorylation of TFEB-unlike other substrates of mTORC1, such as S6K and 4E-BP1- is strictly dependent on the amino-acid-mediated activation of RagC and RagD GTPases, but is insensitive to RHEB activity induced by growth factors. This mechanism has a crucial role in Birt-Hogg-Dubé syndrome, a disorder that is caused by mutations in the RagC and RagD activator folliculin (FLCN) and is characterized by benign skin tumours, lung and kidney cysts and renal cell carcinoma6,7. We found that constitutive activation of TFEB is the main driver of the kidney abnormalities and mTORC1 hyperactivity in a mouse model of Birt-Hogg-Dubé syndrome. Accordingly, depletion of TFEB in kidneys of these mice fully rescued the disease phenotype and associated lethality, and normalized mTORC1 activity. Our findings identify a mechanism that enables differential phosphorylation of mTORC1 substrates, the dysregulation of which leads to kidney cysts and cancer.


Assuntos
Síndrome de Birt-Hogg-Dubé/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/química , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/deficiência , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Síndrome de Birt-Hogg-Dubé/genética , Síndrome de Birt-Hogg-Dubé/patologia , Linhagem Celular , Modelos Animais de Doenças , Ativação Enzimática , Células HeLa , Humanos , Neoplasias Renais/metabolismo , Neoplasias Renais/patologia , Camundongos , Camundongos Knockout , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Fosforilação , Ligação Proteica , Proteínas Proto-Oncogênicas/deficiência , Proteínas Proto-Oncogênicas/genética , Proteína Enriquecida em Homólogo de Ras do Encéfalo/metabolismo , Especificidade por Substrato , Proteína 2 do Complexo Esclerose Tuberosa/metabolismo , Proteínas Supressoras de Tumor/deficiência , Proteínas Supressoras de Tumor/genética
19.
Arterioscler Thromb Vasc Biol ; 40(9): 2143-2158, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32640903

RESUMO

OBJECTIVE: ERα (estrogen receptor alpha) exerts nuclear genomic actions and also rapid membrane-initiated steroid signaling. The mutation of the cysteine 451 into alanine in vivo has recently revealed the key role of this ERα palmitoylation site on some vasculoprotective actions of 17ß-estradiol (E2) and fertility. Here, we studied the in vivo role of the arginine 260 of ERα which has also been described to be involved in its E2-induced rapid signaling with PI-3K (phosphoinositide 3-kinase) as well as G protein in cultured cell lines. Approach and Results: We generated a mouse model harboring a point mutation of the murine counterpart of this arginine into alanine (R264A-ERα). In contrast to the C451A-ERα, the R264A-ERα females are fertile with standard hormonal serum levels and normal control of hypothalamus-pituitary ovarian axis. Although R264A-ERα protein abundance was normal, the well-described membrane ERα-dependent actions of estradiol, such as the rapid dilation of mesenteric arteries and the acceleration of endothelial repair of carotid, were abrogated in R264A-ERα mice. In striking contrast, E2-regulated gene expression was highly preserved in the uterus and the aorta, revealing intact nuclear/genomic actions in response to E2. Consistently, 2 recognized nuclear ERα-dependent actions of E2, namely atheroma prevention and flow-mediated arterial remodeling were totally preserved. CONCLUSIONS: These data underline the exquisite role of arginine 264 of ERα for endothelial membrane-initiated steroid signaling effects of E2 but not for nuclear/genomic actions. This provides the first model of fertile mouse with no overt endocrine abnormalities with specific loss-of-function of rapid ERα signaling in vascular functions.


Assuntos
Lesões das Artérias Carótidas/tratamento farmacológico , Endotélio Vascular/efeitos dos fármacos , Estradiol/farmacologia , Receptor alfa de Estrogênio/agonistas , Terapia de Reposição de Estrogênios , Estrogênios/farmacologia , Fertilidade/efeitos dos fármacos , Artérias Mesentéricas/efeitos dos fármacos , Mutação Puntual , Animais , Aterosclerose/metabolismo , Aterosclerose/patologia , Aterosclerose/prevenção & controle , Lesões das Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/patologia , Lesões das Artérias Carótidas/fisiopatologia , Proliferação de Células/efeitos dos fármacos , Endotélio Vascular/lesões , Endotélio Vascular/metabolismo , Endotélio Vascular/fisiopatologia , Ativação Enzimática , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Ciclo Estral/efeitos dos fármacos , Feminino , Masculino , Artérias Mesentéricas/metabolismo , Artérias Mesentéricas/fisiopatologia , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase Tipo III/metabolismo , Ovariectomia , Reepitelização/efeitos dos fármacos , Transdução de Sinais , Fatores de Tempo , Útero/efeitos dos fármacos , Útero/metabolismo , Remodelação Vascular/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos
20.
Life Sci ; 258: 118151, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32726661

RESUMO

AIMS: Hepatic glucose metabolism involves a variety of catabolic and anabolic pathways, and the dynamic balance of glucose metabolism is regulated in response to environmental and nutritional changes. The molecular mechanism of glucose metabolism in liver is complex and has not been fully elucidated so far. In this study, we hope to elucidate the target and mechanism of cinnamaldehyde (CA) in regulating glucose metabolism. MATERIALS AND METHODS: Molecular image tracing and magnetic capture in combination with an alkynyl-CA probe (Al-CA) was used to show CA covalently binds to α-enolase (ENO1) in both mouse liver and HepG2 cells. Accurate metabolic flow assays subsequently demonstrated that the utilization of glycogenic amino acids and the biosynthesis of tricarboxylic acid (TCA) cycle intermediates were strengthened, which was detected using nontargeted and targeted metabolomics analyses. KEY FINDINGS: Our study shows that CA covalently bonds with ENO1, which affects the stability and activity of ENO1 and changes the dynamic balance of glucose metabolism. The interruption of gluconeogenic reflux by ENO1 enhanced TCA cycle, and eventually led to a decrease in blood glucose and the improvement of mitochondrial efficiency. SIGNIFICANCE: These results provide a detailed description of how CA maintains the dynamic balance of glucose utilization and improves energy metabolism.


Assuntos
Acroleína/análogos & derivados , Biomarcadores Tumorais/metabolismo , Proteínas de Ligação a DNA/metabolismo , Ativação Enzimática/efeitos dos fármacos , Aromatizantes/farmacologia , Gluconeogênese/efeitos dos fármacos , Glucose/metabolismo , Fosfopiruvato Hidratase/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Acroleína/farmacologia , Animais , Ciclo do Ácido Cítrico/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Células Hep G2 , Humanos , Camundongos , Simulação de Acoplamento Molecular
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