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1.
Chem Commun (Camb) ; 60(26): 3575-3578, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38470032

RESUMO

ZnO quantum dots (QDs) supported on porous nitrogen-doped carbon (ZnOQDs/P-NC) exhibited excellent electrochemical performance for the electroreduction of CO2 to CO with a faradaic efficiency of 95.3% and a current density of 21.6 mA cm-2 at -2.2 V vs. Ag/Ag+.

2.
Small ; : e2311694, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38363062

RESUMO

As a fundamental product of CO2 conversion through two-electron transfer, CO is used to produce numerous chemicals and fuels with high efficiency, which has broad application prospects. In this work, it has successfully optimized catalytic activity by fabricating an electrocatalyst featuring crystalline-amorphous CoO-InOx interfaces, thereby significantly expediting CO production. The 1.21%CoO-InOx consists of randomly dispersed CoO crystalline particles among amorphous InOx nanoribbons. In contrast to the same-phase structure, the unique CoO-InOx heterostructure provides plentiful reactive crystalline-amorphous interfacial sites. The Faradaic efficiency of CO (FECO ) can reach up to 95.67% with a current density of 61.72 mA cm-2 in a typical H-cell using MeCN containing 0.5 M 1-Butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6 ) as the electrolyte. Comprehensive experiments indicate that CoO-InOx interfaces with optimization of charge transfer enhance the double-layer capacitance and CO2 adsorption capacity. Theoretical calculations further reveal that the regulating of the electronic structure at interfacial sites not only optimizes the Gibbs free energy of *COOH intermediate formation but also inhibits HER, resulting in high selectivity toward CO.

3.
Sci Total Environ ; 919: 170869, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38342446

RESUMO

In recent years, global warming has led to frequent instances of extremely high temperatures during summer, arousing significant concern about the adverse effects of high temperature. Among these, heat stroke is the most serious, which has detrimental effects on the all organs of human body, especially on brain. However, the comprehensive pathogenesis leading to brain damage remains unclear. In this study, we constructed a mouse model of heat stroke and conducted multi-omics profiling to identify relevant pathogenesis induced by heat stroke. The mice were placed in a constant temperature chamber at 42 °C with a humidity of 50 %, and the criteria for success in modeling were that the rectal temperature reached 42 °C and that the mice were trembling. Then the mice were immediately taken out for further experiments. Firstly, we conducted cFos protein localization and identified the cerebral cortex, especially the anterior cingulate cortex as the region exhibiting the most pronounced damage. Secondly, we performed metabolomics, transcriptomics, and proteomics analysis on cerebral cortex. This multi-omics investigation unveiled noteworthy alterations in proteins and metabolites within pathways associated with neurotransmitter systems, heatstroke-induced mitochondrial dysfunction, encompassing histidine and pentose phosphate metabolic pathways, as well as oxidative stress. In addition, the cerebral cortex exhibited pronounced Reactive Oxygen Species (ROS) production, alongside significant downregulation of the mitochondrial outer membrane protein Tomm40 and mitochondrial permeability transition pore, implicating cerebral cortex mitochondrial dysfunction as the primary instigator of neural impairment. This study marks a significant milestone as the first to employ multi-omics analysis in exploring the molecular mechanisms underlying heat stroke-induced damage in cerebral cortex neurons. It comprehensively identifies all potentially impacted pathways by heat stroke, laying a solid foundation for ensuing research endeavors. Consequently, this study introduces a fresh angle to clinical approaches in heatstroke prevention and treatment, as well as establishes an innovative groundwork for shaping future-forward environmental policies.


Assuntos
Golpe de Calor , Doenças Mitocondriais , Camundongos , Humanos , Animais , Multiômica , Encéfalo/metabolismo , Córtex Cerebral/patologia , Doenças Mitocondriais/complicações , Doenças Mitocondriais/metabolismo
4.
Nat Commun ; 14(1): 7725, 2023 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-38001082

RESUMO

Current therapies for myeloproliferative neoplasms (MPNs) improve symptoms but have limited effect on tumor size. In preclinical studies, tamoxifen restored normal apoptosis in mutated hematopoietic stem/progenitor cells (HSPCs). TAMARIN Phase-II, multicenter, single-arm clinical trial assessed tamoxifen's safety and activity in patients with stable MPNs, no prior thrombotic events and mutated JAK2V617F, CALRins5 or CALRdel52 peripheral blood allele burden ≥20% (EudraCT 2015-005497-38). 38 patients were recruited over 112w and 32 completed 24w-treatment. The study's A'herns success criteria were met as the primary outcome ( ≥ 50% reduction in mutant allele burden at 24w) was observed in 3/38 patients. Secondary outcomes included ≥25% reduction at 24w (5/38), ≥50% reduction at 12w (0/38), thrombotic events (2/38), toxicities, hematological response, proportion of patients in each IWG-MRT response category and ELN response criteria. As exploratory outcomes, baseline analysis of HSPC transcriptome segregates responders and non-responders, suggesting a predictive signature. In responder HSPCs, longitudinal analysis shows high baseline expression of JAK-STAT signaling and oxidative phosphorylation genes, which are downregulated by tamoxifen. We further demonstrate in preclinical studies that in JAK2V617F+ cells, 4-hydroxytamoxifen inhibits mitochondrial complex-I, activates integrated stress response and decreases pathogenic JAK2-signaling. These results warrant further investigation of tamoxifen in MPN, with careful consideration of thrombotic risk.


Assuntos
Transtornos Mieloproliferativos , Neoplasias , Humanos , Transtornos Mieloproliferativos/tratamento farmacológico , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/patologia , Janus Quinase 2/genética , Janus Quinase 2/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Transdução de Sinais , Neoplasias/metabolismo , Tamoxifeno/uso terapêutico , Tamoxifeno/metabolismo , Mutação , Calreticulina/genética , Calreticulina/metabolismo
5.
Nat Cancer ; 4(8): 1193-1209, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37550517

RESUMO

Aging facilitates the expansion of hematopoietic stem cells (HSCs) carrying clonal hematopoiesis-related somatic mutations and the development of myeloid malignancies, such as myeloproliferative neoplasms (MPNs). While cooperating mutations can cause transformation, it is unclear whether distinct bone marrow (BM) HSC-niches can influence the growth and therapy response of HSCs carrying the same oncogenic driver. Here we found different BM niches for HSCs in MPN subtypes. JAK-STAT signaling differentially regulates CDC42-dependent HSC polarity, niche interaction and mutant cell expansion. Asymmetric HSC distribution causes differential BM niche remodeling: sinusoidal dilation in polycythemia vera and endosteal niche expansion in essential thrombocythemia. MPN development accelerates in a prematurely aged BM microenvironment, suggesting that the specialized niche can modulate mutant cell expansion. Finally, dissimilar HSC-niche interactions underpin variable clinical response to JAK inhibitor. Therefore, HSC-niche interactions influence the expansion rate and therapy response of cells carrying the same clonal hematopoiesis oncogenic driver.


Assuntos
Transtornos Mieloproliferativos , Neoplasias , Humanos , Idoso , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/terapia , Transtornos Mieloproliferativos/patologia , Medula Óssea/patologia , Medula Óssea/fisiologia , Células-Tronco Hematopoéticas/patologia , Osso e Ossos/patologia , Microambiente Tumoral/genética
6.
Chem Commun (Camb) ; 59(64): 9746-9749, 2023 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-37482813

RESUMO

A novel and tunable synthesis of Fe/CuOx bimetallic catalysts has been achieved via a simple Fe-precipitation and calcination method, which was used for highly efficient CO2 electroreduction to control the wide-ranging CO to H2 ratio by simply changing the ratio of metals. The faradaic efficiency of CO could reach 86.1% with a current density of 49.1 mA cm-2. The ratio of CO/H2 could reach 1.94 to 6.18 and it was discovered that the Fe/CuOx bimetallic catalysts could easily get different ratios of syngas, which can be applied directly in industry.

7.
Clin Exp Med ; 23(4): 1307-1316, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36168074

RESUMO

The relationship between plasma EBV-DNA load (PEDL) and Epstein-Barr virus (EBV)-encoded small RNA (EBER) during the early treatment of lymphoma remains unclear. We explored discrepancies in PEDL and variables associated with EBER and evaluated the consistency between EBER and qualitative analysis of PEDL (qPEDL). Serial measurements of PEDL were performed to determine the dynamic changes of PEDL in early treatment of lymphoma. As a result, the median PEDL of non-Hodgkin's lymphoma NKT cell subtype (NHL-NKT) was higher than that of non-Hodgkin's lymphoma B cell subtype (NHL-B), the median PEDL of extranodal NK/T cell lymphoma (ENKTCL) was higher than that of diffuse large B cell lymphoma (DLBCL), and the median PEDL of EBER positive was higher than that of EBER negative. Age, Ki-67 ≧ 80%, Bcl-2 ≧ 80%, p53, and qPEDL were related to EBER. The PEDL could distinguish NHL-B, DLBCL, NHL-NKT, and ENKTCL from other lymphoma subtypes. EBER-positive patients spent more time with viral "turn negative (TN)" and "continuous positive (CP)" and less time with viral "continuous negative (CN)." The median PEDL of CP was higher than that of TN. In conclusion, although EBER affects the levels of PEDL in general, it has poor concordance with qPEDL. Our results show, for the first time, that high PEDL and positive EBER present a strong association with viral recurrence and persistent infection in the early treatment of lymphoma.


Assuntos
Infecções por Vírus Epstein-Barr , Linfoma Extranodal de Células T-NK , Linfoma Difuso de Grandes Células B , Humanos , Herpesvirus Humano 4/genética , Infecções por Vírus Epstein-Barr/complicações , Infecção Persistente , Linfoma Difuso de Grandes Células B/patologia , DNA Viral , RNA Viral
8.
Medicine (Baltimore) ; 101(41): e30998, 2022 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-36254081

RESUMO

BACKGROUND: To date, there has been little agreement on what drug is the "best" drug for treating severe COVID-19 patients. This study aimed to assess the efficacy and safety of different medications available at present for severe COVID-19. METHODS: We searched databases for randomized controlled trials (RCTs) published up to February 28, 2022, with no language restrictions, of medications recommended for patients (aged 16 years or older) with severe COVID-19 infection. We extracted data on trials and patient characteristics, and the following primary outcomes: all-cause mortality (ACM), and treatment-emergent adverse events (TEAEs). RESULTS: We identified 4021 abstracts and of these included 48 RCTs comprising 9147 participants through database searches and other sources. For decrease in ACM, we found that ivermectin/doxycycline, C-IVIG (i.e., a hyperimmune anti-COVID-19 intravenous immunoglobulin), methylprednisolone, interferon-beta/standard-of-care (SOC), interferon-beta-1b, convalescent plasma, remdesivir, lopinavir/ritonavir, immunoglobulin gamma, high dosage sarilumab (HS), auxora, and imatinib were effective when compared with placebo or SOC group. We found that colchicine and interferon-beta/SOC were only associated with the TEAEs of severe COVID-19 patients. CONCLUSION: This study suggested that ivermectin/doxycycline, C-IVIG, methylprednisolone, interferon-beta/SOC, interferon-beta-1b, convalescent plasma (CP), remdesivir, lopinavir/ritonavir, immunoglobulin gamma, HS, auxora, and imatinib were efficacious for treating severe COVID-19 patients. We found that most medications were safe in treating severe COVID-19. More large-scale RCTs are still needed to confirm the results of this study.


Assuntos
Tratamento Farmacológico da COVID-19 , COVID-19 , Infecções por Coronavirus , Pneumonia Viral , COVID-19/terapia , Colchicina/uso terapêutico , Infecções por Coronavirus/terapia , Doxiciclina/uso terapêutico , Humanos , Mesilato de Imatinib/uso terapêutico , Imunização Passiva , Imunoglobulinas Intravenosas/uso terapêutico , Interferon beta-1b/uso terapêutico , Ivermectina/efeitos adversos , Lopinavir/uso terapêutico , Metilprednisolona/uso terapêutico , Metanálise em Rede , Pandemias , Pneumonia Viral/terapia , Ensaios Clínicos Controlados Aleatórios como Assunto , Ritonavir/uso terapêutico , Soroterapia para COVID-19
9.
J Appl Stat ; 49(4): 858-883, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35707816

RESUMO

Modeling cyber threats, such as the computer malicious software (malware) propagation dynamics in cyberspace, is an important research problem because models can deepen our understanding of dynamical cyber threats. In this paper, we study the statistical modeling of the macro-level evolution of dynamical cyber attacks. Specifically, we propose a Bayesian structural time series approach for modeling the computer malware propagation dynamics in cyberspace. Our model not only possesses the parsimony property (i.e. using few model parameters) but also can provide the predictive distribution of the dynamics by accommodating uncertainty. Our simulation study shows that the proposed model can fit and predict the computer malware propagation dynamics accurately, without requiring to know the information about the underlying attack-defense interaction mechanism and the underlying network topology. We use the model to study the propagation of two particular kinds of computer malware, namely the Conficker and Code Red worms, and show that our model has very satisfactory fitting and prediction accuracies.

10.
Nat Commun ; 13(1): 543, 2022 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-35087060

RESUMO

The sympathetic nervous system has been evolutionary selected to respond to stress and activates haematopoietic stem cells via noradrenergic signals. However, the pathways preserving haematopoietic stem cell quiescence and maintenance under proliferative stress remain largely unknown. Here we found that cholinergic signals preserve haematopoietic stem cell quiescence in bone-associated (endosteal) bone marrow niches. Bone marrow cholinergic neural signals increase during stress haematopoiesis and are amplified through cholinergic osteoprogenitors. Lack of cholinergic innervation impairs balanced responses to chemotherapy or irradiation and reduces haematopoietic stem cell quiescence and self-renewal. Cholinergic signals activate α7 nicotinic receptor in bone marrow mesenchymal stromal cells leading to increased CXCL12 expression and haematopoietic stem cell quiescence. Consequently, nicotine exposure increases endosteal haematopoietic stem cell quiescence in vivo and impairs hematopoietic regeneration after haematopoietic stem cell transplantation in mice. In humans, smoking history is associated with delayed normalisation of platelet counts after allogeneic haematopoietic stem cell transplantation. These results suggest that cholinergic signals preserve stem cell quiescence under proliferative stress.


Assuntos
Colinérgicos/metabolismo , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/metabolismo , Animais , Medula Óssea/metabolismo , Quimiocina CXCL12/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Transplante de Células-Tronco Hematopoéticas , Humanos , Células-Tronco Mesenquimais/metabolismo , Camundongos , Receptores Adrenérgicos beta 3/metabolismo , Fatores de Risco
11.
J Med Virol ; 94(4): 1617-1626, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34882805

RESUMO

This study aimed to assess the efficacy and safety of different medications available at present for severe coronavirus disease 2019 (COVID-19) infection. We searched databases for randomized controlled trials (RCTs) published up to April 30, 2021, with Chinese or English language restriction, of medications recommended for patients (aged 18 years or older) with severe COVID-19 infection. We extracted data on trials and patient characteristics, and the following primary outcomes: all-cause mortality (ACM), and treatment-emergent adverse events (TEAEs). We identified 1855 abstracts and of these included 15 RCTs comprising 3073 participants through database searches and other sources. In terms of efficacy, compared with the standard of care (SOC) group, no significant decrease in ACM was found in α-lipoic acid, convalescent plasma (CP), azithromycin, tocilizumab, methylprednisolone, interferon beta, CP/SOC, high dosage sarilumab, low dosage sarilumab, remdesivir, lopinavir-ritonavir, auxora, and placebo group. Compared with placebo, we found that a significant decrease in ACM was only found in methylprednisolone (odds ratio [OR]: 0.16, 95% confidence interval [CI]: 0.03-0.75]. With respect to TEAEs, the CP group showed lower TEAEs than placebo (OR: 0.07, 95% CI: 0.01-0.58) or SOC (OR: 0.05, 95% CI: 0.01-0.42) group for the therapy of severe COVID-19 patients. This study only demonstrated that methylprednisolone was superior to placebo in treating patients with severe COVID-19 infection. Meanwhile, this further confirmed that the safety of other treatment interventions might be inferior to CP for the therapy of severe COVID-19 patients.


Assuntos
COVID-19/terapia , Metanálise em Rede , COVID-19/mortalidade , Humanos , SARS-CoV-2 , Índice de Gravidade de Doença , Resultado do Tratamento
12.
Aging (Albany NY) ; 13(18): 21866-21902, 2021 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-34531332

RESUMO

BACKGROUND: Many recent studies have investigated the role of drug interventions for coronavirus disease 2019 (COVID-19) infection. However, an important question has been raised about how to select the effective and secure medications for COVID-19 patients. The aim of this analysis was to assess the efficacy and safety of the various medications available for severe and non-severe COVID-19 patients based on randomized placebo-controlled trials (RPCTs). METHODS: We did an updated network meta-analysis. We searched the databases from inception until July 31, 2021, with no language restrictions. We included RPCTs comparing 49 medications and placebo in the treatment of severe and non-severe patients (aged 18 years or older) with COVID-19 infection. We extracted data on the trial and patient characteristics, and the following primary outcomes: all-cause mortality, the ratios of virological cure, and treatment-emergent adverse events. Odds ratio (OR) and their 95% confidence interval (CI) were used as effect estimates. RESULTS: From 3,869 publications, we included 61 articles related to 73 RPCTs (57 in non-severe COVID-19 patients and 16 in severe COVID-19 patients), comprising 20,680 patients. The mean sample size was 160 (interquartile range 96-393) in this study. The median duration of follow-up drugs intervention was 28 days (interquartile range 21-30). For increase in virological cure, we only found that proxalutamide (OR 9.16, 95% CI 3.15-18.30), ivermectin (OR 6.33, 95% CI 1.22-32.86), and low dosage bamlanivimab (OR 5.29, 95% CI 1.12-24.99) seemed to be associated with non-severe COVID-19 patients when compared with placebo, in which proxalutamide seemed to be better than low dosage bamlanivimab (OR 5.69, 95% CI 2.43-17.65). For decrease in all-cause mortality, we found that proxalutamide (OR 0.13, 95% CI 0.09-0.19), imatinib (OR 0.49, 95% CI 0.25-0.96), and baricitinib (OR 0.58, 95% CI 0.42-0.82) seemed to be associated with non-severe COVID-19 patients; however, we only found that immunoglobulin gamma (OR 0.27, 95% CI 0.08-0.89) was related to severe COVID-19 patients when compared with placebo. For change in treatment-emergent adverse events, we only found that sotrovimab (OR 0.21, 95% CI 0.13-0.34) was associated with non-severe COVID-19 patients; however, we did not find any medications that presented a statistical difference when compared with placebo among severe COVID-19 patients. CONCLUSION: We conclude that marked variations exist in the efficacy and safety of medications between severe and non-severe patients with COVID-19. It seems that monoclonal antibodies (e.g., low dosage bamlanivimab, baricitinib, imatinib, and sotrovimab) are a better choice for treating severe or non-severe COVID-19 patients. Clinical decisions to use preferentially medications should carefully consider the risk-benefit profile based on efficacy and safety of all active interventions in patients with COVID-19 at different levels of infection.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Tratamento Farmacológico da COVID-19 , Fatores Imunológicos/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Azetidinas/uso terapêutico , COVID-19/mortalidade , Humanos , Mesilato de Imatinib/uso terapêutico , Metanálise em Rede , Oxazóis/uso terapêutico , Purinas/uso terapêutico , Pirazóis/uso terapêutico , SARS-CoV-2 , Índice de Gravidade de Doença , Sulfonamidas/uso terapêutico , Tioidantoínas/uso terapêutico , Resultado do Tratamento
13.
J Biol Chem ; 296: 100133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33268378

RESUMO

Receptors for the peptide hormones glucagon-like peptide-1 (GLP-1R), glucose-dependent insulinotropic polypeptide (GIPR), and glucagon (GCGR) are important regulators of insulin secretion and energy metabolism. GLP-1R agonists have been successfully deployed for the treatment of type 2 diabetes, but it has been suggested that their efficacy is limited by target receptor desensitization and downregulation due to recruitment of ß-arrestins. Indeed, recently described GLP-1R agonists with reduced ß-arrestin-2 recruitment have delivered promising results in preclinical and clinical studies. We therefore aimed to determine if the same phenomenon could apply to the closely related GIPR and GCGR. In HEK293 cells depleted of both ß-arrestin isoforms the duration of G protein-dependent cAMP/PKA signaling was increased in response to the endogenous ligand for each receptor. Moreover, in wildtype cells, "biased" GLP-1, GCG, and GIP analogs with selective reductions in ß-arrestin-2 recruitment led to reduced receptor endocytosis and increased insulin secretion over a prolonged stimulation period, although the latter effect was only seen at high agonist concentrations. Biased GCG analogs increased the duration of cAMP signaling, but this did not lead to increased glucose output from hepatocytes. Our study provides a rationale for the development of GLP-1R, GIPR, and GCGR agonists with reduced ß-arrestin recruitment, but further work is needed to maximally exploit this strategy for therapeutic purposes.


Assuntos
AMP Cíclico/metabolismo , Polipeptídeo Inibidor Gástrico/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Incretinas/farmacologia , Receptores dos Hormônios Gastrointestinais/metabolismo , beta-Arrestinas/metabolismo , Animais , Polipeptídeo Inibidor Gástrico/genética , Glucagon/metabolismo , Peptídeo 1 Semelhante ao Glucagon/genética , Receptor do Peptídeo Semelhante ao Glucagon 1/genética , Células HEK293 , Humanos , Secreção de Insulina , Ligantes , Camundongos , Camundongos Endogâmicos C57BL , Receptores dos Hormônios Gastrointestinais/genética , Transdução de Sinais , beta-Arrestinas/genética
14.
Int J Mol Sci ; 21(21)2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-33182425

RESUMO

The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, using biorthogonal labelling of GLP-1R to determine its localisation and degradation after treatment with GLP-1, exendin-4 and several further GLP-1R agonist peptides. We also characterised the effect of a rare GLP1R coding variant, T149M, and the role of endosomal peptidase endothelin-converting enzyme-1 (ECE-1), in GLP1R trafficking. Our data reveal how treatment with GLP-1 versus exendin-4 is associated with preferential GLP-1R targeting towards a recycling pathway. GLP-1, but not exendin-4, is a substrate for ECE-1, and the resultant propensity to intra-endosomal degradation, in conjunction with differences in binding affinity, contributes to alterations in GLP-1R trafficking behaviours and degradation. The T149M GLP-1R variant shows reduced signalling and internalisation responses, which is likely to be due to disruption of the cytoplasmic region that couples to intracellular effectors. These observations provide insights into how ligand- and genotype-specific factors can influence GLP-1R trafficking.


Assuntos
Endocitose/fisiologia , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/fisiologia , Transporte Proteico/fisiologia , Animais , Linhagem Celular , Citoplasma/metabolismo , Endossomos/metabolismo , Endossomos/fisiologia , Enzimas Conversoras de Endotelina/metabolismo , Células HEK293 , Humanos , Ligantes , Camundongos
15.
Br J Pharmacol ; 177(17): 3905-3923, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32436216

RESUMO

BACKGROUND AND PURPOSE: Amino acid substitutions at the N-termini of glucagon-like peptide-1 (GLP-1) receptor agonist peptides result in distinct patterns of intracellular signalling, sub-cellular trafficking and efficacy in vivo. Here, we to determine whether sequence differences at the ligand C-termini of clinically approved GLP-1 receptor agonists exendin-4 and lixisenatide lead to similar phenomena. EXPERIMENTAL APPROACH: Exendin-4, lixisenatide and N-terminally substituted analogues with biased signalling characteristics were compared across a range of in vitro trafficking and signalling assays in different cell types. Fluorescent ligands and new time-resolved FRET approaches were developed to study agonist behaviours at the cellular and sub-cellular level. Anti-hyperglycaemic and anorectic effects of each parent ligand and their biased derivatives were assessed in mice. KEY RESULTS: Lixisenatide and exendin-4 showed equal binding affinity, but lixisenatide was fivefold less potent for cAMP signalling. Both peptides induced extensive GLP-1 receptor clustering in the plasma membrane and were rapidly endocytosed, but the GLP-1 receptor recycled more slowly to the cell surface after lixisenatide treatment. These combined deficits resulted in reduced maximal sustained insulin secretion and reduced anti-hyperglycaemic and anorectic effects in mice with lixisenatide. N-terminal substitution of His1 by Phe1 to both ligands had favourable effects on their pharmacology, resulting in improved insulin release and lowering of blood glucose. CONCLUSION AND IMPLICATIONS: Changes to the C-terminus of exendin-4 affect signalling potency and GLP-1 receptor trafficking via mechanisms unrelated to GLP-1 receptor occupancy. These differences were associated with changes in their ability to control blood glucose and therefore may be therapeutically relevant.


Assuntos
Receptor do Peptídeo Semelhante ao Glucagon 1 , Peptídeos , Animais , Exenatida/farmacologia , Hipoglicemiantes/farmacologia , Insulina , Camundongos , Peptídeos/farmacologia
16.
ACS Pharmacol Transl Sci ; 3(2): 345-360, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32296773

RESUMO

Signal bias and membrane trafficking have recently emerged as important considerations in the therapeutic targeting of the glucagon-like peptide-1 receptor (GLP-1R) in type 2 diabetes and obesity. In the present study, we have evaluated a peptide series with varying sequence homology between native GLP-1 and exendin-4, the archetypal ligands on which approved GLP-1R agonists are based. We find notable differences in agonist-mediated cyclic AMP signaling, recruitment of ß-arrestins, endocytosis, and recycling, dependent both on the introduction of a His → Phe switch at position 1 and the specific midpeptide helical regions and C-termini of the two agonists. These observations were linked to insulin secretion in a beta cell model and provide insights into how ligand factors influence GLP-1R function at the cellular level.

18.
Prog Lipid Res ; 74: 145-159, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30951736

RESUMO

The increased adipose tissue mass of obese individuals enhances the risk of metabolic syndrome, type 2 diabetes and cardiovascular diseases. During pathological expansion of adipose tissue, multiple molecular controls of lipid storage, adipocyte turn-over and endocrine secretion are perturbed and abnormal lipid metabolism results in a distinct lipid profile. There is a role for ceramides and sphingosine 1-phosphate (S1P) in inducing adipose dysfunction. For instance, the alteration of ceramide biosynthesis, through the de-regulation of key enzymes, results in aberrant formation of ceramides (e.g. C16:0 and C18:0) which block insulin signaling and promote adipose inflammation. Furthermore, S1P can induce defective adipose tissue phenotypes by promoting chronic inflammation and inhibiting adipogenesis. These abnormal changes are discussed in the context of possible therapeutic approaches to re-establish normal adipose function and to, thereby, increase insulin sensitivity in type 2 diabetes. Such novel approaches include blockade of ceramide biosynthesis using inhibitors of sphingomyelinase or dihydroceramide desaturase and by antagonism of S1P receptors, such as S1P2.


Assuntos
Tecido Adiposo/metabolismo , Tecido Adiposo/fisiopatologia , Ceramidas/metabolismo , Lisofosfolipídeos/metabolismo , Esfingosina/análogos & derivados , Animais , Humanos , Esfingosina/metabolismo
19.
Mol Cell Biochem ; 439(1-2): 141-150, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28780753

RESUMO

Peripheral nerve injury is a common disease with a low recovery rate. A better understanding of the molecular changes underlying peripheral nerve injury and regeneration may contribute to the development of novel therapies for the treatment of peripheral nerve injury. In the current study, we analyzed differentially expressed genes in rat sciatic nerve stumps at 1, 4, 7, and 14 days post nerve crush and built biological functional networks at each time point. Our outcomes suggested that "Neurological Disease" involved networks were significant at 1 day post nerve crush, "Cellular Assembly and Organization" involved networks were important at 4 and 7 days post nerve crush, while "Tissue Morphology" involved networks were important at 14 days post nerve crush. We also investigated the temporal expression patterns as well as central genes of these critical networks. Taken together, our study revealed genetic networks and gene-gene interactions in the injured nerve stumps and thus might enhance our understanding of peripheral nerve regeneration.


Assuntos
Redes Reguladoras de Genes , Regeneração Nervosa , Proteínas do Tecido Nervoso , Traumatismos dos Nervos Periféricos , Nervo Isquiático/fisiologia , Animais , Masculino , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Traumatismos dos Nervos Periféricos/genética , Traumatismos dos Nervos Periféricos/metabolismo , Traumatismos dos Nervos Periféricos/patologia , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/patologia
20.
Front Pharmacol ; 8: 820, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29249966

RESUMO

Dysregulation of Hedgehog (Hh) signaling pathway is one of the hallmarks of pancreatic ductal adenocarcinoma (PDA). Lithium, a clinical mood stabilizer for the treatment of mental disorders, is known to suppress tumorigenic potential of PDA cells by targeting the Hh/Gli signaling pathway. In this study, we investigated the molecular mechanism of lithium induced down-regulation of Hh/Gli1. Our data show that lithium promotes the poly-ubiquitination and proteasome-mediated degradation of Gli1 through activating E3 ligase ITCH. Additionally, lithium enhances interaction between Gli1 and SUFU via suppressing GSK3ß, which phosphorylates SUFU and destabilizes the SUFU-Gli1 inhibitory complex. Our studies illustrate a novel mechanism by which lithium suppresses Hh signaling via simultaneously promoting ITCH-dependent Gli1 ubiquitination/degradation and SUFU-mediated Gli1 inhibition.

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