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1.
Proc Natl Acad Sci U S A ; 117(35): 21723-21730, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817560

RESUMO

G proteins are activated when they associate with G protein-coupled receptors (GPCRs), often in response to agonist-mediated receptor activation. It is generally thought that agonist-induced receptor-G protein association necessarily promotes G protein activation and, conversely, that activated GPCRs do not interact with G proteins that they do not activate. Here we show that GPCRs can form agonist-dependent complexes with G proteins that they do not activate. Using cell-based bioluminescence resonance energy transfer (BRET) and luminescence assays we find that vasopressin V2 receptors (V2R) associate with both Gs and G12 heterotrimers when stimulated with the agonist arginine vasopressin (AVP). However, unlike V2R-Gs complexes, V2R-G12 complexes are not destabilized by guanine nucleotides and do not promote G12 activation. Activating V2R does not lead to signaling responses downstream of G12 activation, but instead inhibits basal G12-mediated signaling, presumably by sequestering G12 heterotrimers. Overexpressing G12 inhibits G protein receptor kinase (GRK) and arrestin recruitment to V2R and receptor internalization. Formyl peptide (FPR1 and FPR2) and Smoothened (Smo) receptors also form complexes with G12 that are insensitive to nucleotides, suggesting that unproductive GPCR-G12 complexes are not unique to V2R. These results indicate that agonist-dependent receptor-G protein association does not always lead to G protein activation and may in fact inhibit G protein activation.


Assuntos
Subunidades alfa G12-G13 de Proteínas de Ligação ao GTP/metabolismo , Receptores Acoplados a Proteínas-G/agonistas , Receptores Acoplados a Proteínas-G/metabolismo , Técnicas de Transferência de Energia por Ressonância de Bioluminescência/métodos , AMP Cíclico/metabolismo , Subunidades alfa G12-G13 de Proteínas de Ligação ao GTP/fisiologia , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/fisiologia , Proteínas de Ligação ao GTP/metabolismo , Células HEK293 , Humanos , Ligantes , Ligação Proteica/fisiologia , Receptores de Vasopressinas/metabolismo , Transdução de Sinais/fisiologia , Vasopressinas/metabolismo , beta-Arrestinas/metabolismo
3.
Mol Pharmacol ; 98(4): 410-424, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32665252

RESUMO

Evidence from several novel opioid agonists and knockout animals suggests that improved opioid therapeutic window, notably for analgesia versus respiratory depression, is a result of ligand bias downstream of activation of the µ-opioid receptor (MOR) toward G protein signaling and away from other pathways, such as arrestin recruitment. Here, we argue that published claims of opioid bias based on application of the operational model of agonism are frequently confounded by failure to consider the assumptions of the model. These include failure to account for intrinsic efficacy and ceiling effects in different pathways, distortions introduced by analysis of amplified (G protein) versus linear (arrestin) signaling mechanisms, and nonequilibrium effects in a dynamic signaling cascade. We show on both theoretical and experimental grounds that reduced intrinsic efficacy that is unbiased across different downstream pathways, when analyzed without due considerations, does produce apparent but erroneous MOR ligand bias toward G protein signaling, and the weaker the G protein partial agonism is the greater the apparent bias. Experimentally, such apparently G protein-biased opioids have been shown to exhibit low intrinsic efficacy for G protein signaling when ceiling effects are properly accounted for. Nevertheless, such agonists do display an improved therapeutic window for analgesia versus respiratory depression. Reduced intrinsic efficacy for G proteins rather than any supposed G protein bias provides a more plausible, sufficient explanation for the improved safety. Moreover, genetic models of G protein-biased opioid receptors and replication of previous knockout experiments suggest that reduced or abolished arrestin recruitment does not improve therapeutic window for MOR-induced analgesia versus respiratory depression. SIGNIFICANCE STATEMENT: Efforts to improve safety of µ-opioid analgesics have focused on agonists that show signaling bias for the G protein pathway versus other signaling pathways. This review provides theoretical and experimental evidence showing that failure to consider the assumptions of the operational model can lead to large distortions and overestimation of actual bias. We show that low intrinsic efficacy is a major determinant of these distortions, and pursuit of appropriately reduced intrinsic efficacy should guide development of safer opioids.


Assuntos
Analgésicos Opioides/farmacologia , Receptores Acoplados a Proteínas-G/metabolismo , Receptores Opioides mu/metabolismo , Animais , Humanos , Ligantes , Receptores Acoplados a Proteínas-G/agonistas , Transdução de Sinais/efeitos dos fármacos
5.
Int J Infect Dis ; 96: 348-351, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32389847

RESUMO

ACE2 is a receptor of entry of SARS-CoV-2 into the host cells, and its upregulation has been implicated in increasing susceptibility of individuals to this infection. The clinical picture of COVID-19 suggests a role of ACE2 blockade, rather than its overexpression, in causing the pathogenesis. ACE2 blockade results in increased angiotensin II activity with simultaneous hampering of functions of angiotensin-(1-7)/MasR axis. Acute respiratory distress due to interstitial pulmonary fibrosis, cardiomyopathy and shock reported in COVID-19 patients can be explained by imbalanced angiotensin II and angiotensin-(1-7) activities. Failure of angiotensin II type 1 receptor blockers to control the severity of SARS-CoV-2 infections indicates the importance of simultaneous induction of angiotensin-(1-7)/MasR axis for correcting pathological conditions in COVID-19 through its anti-fibrotic, anti-inflammatory, vasodilatory, and cardioprotective roles. MasR agonists have also shown organ protective effects in a number of animal studies. Unfortunately, these agonists have not been tested in clinical studies. Their evaluation in seriously ill COVID-19 patients is urgently warranted to reduce mortality due to infection.


Assuntos
Betacoronavirus , Infecções por Coronavirus/tratamento farmacológico , Pneumonia Viral/tratamento farmacológico , Proteínas Proto-Oncogênicas/agonistas , Receptores Acoplados a Proteínas-G/agonistas , Angiotensina II/fisiologia , Animais , Infecções por Coronavirus/etiologia , Humanos , Pandemias , Peptidil Dipeptidase A/fisiologia , Pneumonia Viral/etiologia
6.
Proc Natl Acad Sci U S A ; 117(23): 13117-13126, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32434907

RESUMO

More than 800 G protein-coupled receptors (GPCRs) comprise the largest class of membrane receptors in humans. While there is ample biological understanding and many approved drugs for prototypic GPCRs, most GPCRs still lack well-defined biological ligands and drugs. Here, we report our efforts to tap the potential of understudied GPCRs by developing yeast-based technologies for high-throughput clustered regularly interspaced short palindromic repeats (CRISPR) engineering and GPCR ligand discovery. We refer to these technologies collectively as Dynamic Cyan Induction by Functional Integrated Receptors, or DCyFIR. A major advantage of DCyFIR is that GPCRs and other assay components are CRISPR-integrated directly into the yeast genome, making it possible to decode ligand specificity by profiling mixtures of GPCR-barcoded yeast strains in a single tube. To demonstrate the capabilities of DCyFIR, we engineered a yeast strain library of 30 human GPCRs and their 300 possible GPCR-Gα coupling combinations. Profiling of these 300 strains, using parallel (DCyFIRscreen) and multiplex (DCyFIRplex) DCyFIR modes, recapitulated known GPCR agonism with 100% accuracy, and identified unexpected interactions for the receptors ADRA2B, HCAR3, MTNR1A, S1PR1, and S1PR2. To demonstrate DCyFIR scalability, we profiled a library of 320 human metabolites and discovered several GPCR-metabolite interactions. Remarkably, many of these findings pertained to understudied pharmacologically dark receptors GPR4, GPR65, GPR68, and HCAR3. Experiments on select receptors in mammalian cells confirmed our yeast-based observations, including our discovery that kynurenic acid activates HCAR3 in addition to GPR35, its known receptor. Taken together, these findings demonstrate the power of DCyFIR for identifying ligand interactions with prototypic and understudied GPCRs.


Assuntos
Sistemas CRISPR-Cas/genética , Ensaios de Triagem em Larga Escala/métodos , Receptores Acoplados a Proteínas-G/metabolismo , Análise Custo-Benefício , Células HEK293 , Ensaios de Triagem em Larga Escala/economia , Humanos , Ligantes , Receptores Acoplados a Proteínas-G/agonistas , Receptores Acoplados a Proteínas-G/antagonistas & inibidores , Receptores Acoplados a Proteínas-G/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais/efeitos dos fármacos
7.
FASEB J ; 34(5): 6008-6016, 2020 05.
Artigo em Inglês | MEDLINE | ID: covidwho-46910

RESUMO

The sudden outbreak of COVID-19 has led to more than seven thousand deaths. Unfortunately, there are no specific drugs available to cure this disease. Type 2 taste receptors (TAS2Rs) may play an important role in host defense mechanisms. Based on the idea of host-directed therapy (HDT), we performed a negative co-expression analysis using big data of 60 000 Affymetrix expression arrays and 5000 TCGA data sets to determine the functions of TAS2R10, which can be activated by numerous bitter substances. Excitingly, we found that the main functions of TAS2R10 involved controlling infectious diseases caused by bacteria, viruses, and parasites, suggesting that TAS2R10 is a key trigger of host defense pathways. To quickly guide the clinical treatment of 2019-nCoV, we searched currently available drugs that are agonists of TAS2Rs. We identified many cheap, available, and safe medicines, such as diphenidol, quinine, chloroquine, artemisinin, chlorpheniramine, yohimbine, and dextromethorphan, which may target the most common symptoms caused by 2019-nCoV. We suggest that a cocktail-like recipe of existing bitter drugs may help doctors to fight this catastrophic disease and that the general public may drink or eat bitter substances, such as coffee, tea, or bitter vegetables, to reduce the risk of infection.


Assuntos
Antivirais/uso terapêutico , Biologia Computacional , Infecções por Coronavirus/tratamento farmacológico , Pneumonia Viral/tratamento farmacológico , Receptores Acoplados a Proteínas-G/agonistas , Antivirais/farmacologia , Betacoronavirus , Bases de Dados Genéticas , Bases de Dados de Produtos Farmacêuticos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Pandemias , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores Acoplados a Proteínas-G/genética
8.
Food Chem ; 324: 126864, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344344

RESUMO

Sugar replacement is still an active issue in the food industry. The use of structure-taste relationships remains one of the most rational strategy to expand the chemical space associated to sweet taste. A new machine learning model has been setup based on an update of the SweetenersDB and on open-source molecular features. It has been implemented on a freely accessible webserver. Cellular functional assays show that the sweet taste receptor is activated in vitro by a new scaffold of natural compounds identified by the in silico protocol. The newly identified sweetener belongs to the lignan chemical family and opens a new chemical space to explore.


Assuntos
Aprendizado de Máquina , Edulcorantes/análise , Paladar/fisiologia , Humanos , Receptores Acoplados a Proteínas-G/agonistas , Receptores Acoplados a Proteínas-G/metabolismo
9.
Am J Physiol Gastrointest Liver Physiol ; 318(5): G980-G987, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32308039

RESUMO

Glucagon-like peptide (GLP)-1 and -2-secreting L cells have been shown to express the bile acid receptor Takeda G protein-receptor-5 (TGR5) and increase secretion upon receptor activation. Previous studies have explored GLP-1 secretion following acute TGR5 activation, but chronic activation and GLP-2 responses have not been characterized. In this study, we aimed to investigate the consequences of pharmacological TGR5 receptor activation on L cell hormone production in vivo using the specific TGR5 agonist RO5527239 and the GLP-2 receptor knockout mouse. Here, we show that 1) TGR5 receptor activation led to increased GLP-1 and GLP-2 content in the colon, which 2) was associated with an increased small intestinal weight that 3) was GLP-2 dependent. Additionally, we report that TGR5-mediated gallbladder filling occurred independently of GLP-2 signaling. In conclusion, we demonstrate that pharmacological TGR5 receptor activation stimulates L cells, triggering GLP-2-dependent intestinal adaption in mice.NEW & NOTEWORTHY Using the specific Takeda G protein-receptor-5 (TGR5) agonist RO5527239 and GLP-2 receptor knockout mice, we show that activation of TGR5 led to the increase in colonic GLP-1 and GLP-2 concomitant with a GLP-2 dependent growth response in the proximal portion of the small intestine.


Assuntos
Proliferação de Células/efeitos dos fármacos , Células Enteroendócrinas/efeitos dos fármacos , Peptídeo 2 Semelhante ao Glucagon/metabolismo , Intestino Delgado/efeitos dos fármacos , Ácidos Isonipecóticos/farmacologia , Oximas/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Animais , Colo/efeitos dos fármacos , Colo/crescimento & desenvolvimento , Colo/metabolismo , Células Enteroendócrinas/metabolismo , Feminino , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 2/genética , Receptor do Peptídeo Semelhante ao Glucagon 2/metabolismo , Intestino Delgado/crescimento & desenvolvimento , Intestino Delgado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Acoplados a Proteínas-G/metabolismo , Transdução de Sinais
10.
Med Sci Monit ; 26: e920628, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32242546

RESUMO

BACKGROUND Due to its remarkable effect in controlling glycometabolism, relatively simple operation, and low risk of complications, sleeve gastrectomy (SG) has become the preferred surgical treatment for type II diabetes mellitus. Increased blood glucose in the body can cause damage to functional cells. MATERIAL AND METHODS Long non-coding RNA SNHG5 expression and TGR5 in serum were analyzed by real-time PCR. A diabetic cell model was established by culturing normal human intestinal epithelial cells NCM460 and DLD-1 with high-glucose and high-fat medium. CCK-8 assay, TUNEL assay, and flow cytometry were used to assess cell growth and apoptosis, respectively. The secretion of lactate dehydrogenase (LDH) was detected using the LDH Cytotoxicity Kit. lncRNA SNHG5 was downregulated by siRNA. The changes in expression of SNHG5, TGR5, Akt, p65, and Bcl-2 were analyzed by real-time PCR assay or Western blot. RESULTS In 40 type II diabetes patients who underwent sleeve gastrectomy, the expression of SNHG5 decreased and the expression of TGR5 increased compared with that before the operation. After high-glucose and high-fat culture, cell growth was inhibited and cell apoptosis increased significantly. The expression of SNHG5 was increased and TGR5 was decreased with high-glucose and high-fat culture. However, high glucose and high fat showed an opposite trend for cell growth, apoptosis, and LDH release under inhibition of SNHG5. The expression levels of TGR5 and Akt, p65, and Bcl-2 were also returned to normal by SNHG5 inhibition. CONCLUSIONS By downregulating expression of the SNHG5 gene and then altering expression of the TGR5 gene, the damage to colorectal cells induced by high glucose was alleviated. This may be one of the mechanisms underlying the effect of sleeve gastric surgery in treatment of diabetes mellitus.


Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 2/cirurgia , Gastrectomia/métodos , Receptores Acoplados a Proteínas-G/metabolismo , Apoptose , Proliferação de Células , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Regulação para Baixo , Regulação Neoplásica da Expressão Gênica , Humanos , Secreção de Insulina , Obesidade/complicações , Obesidade/metabolismo , Obesidade/cirurgia , RNA Longo não Codificante , Receptores Acoplados a Proteínas-G/agonistas
11.
Einstein (Sao Paulo) ; 18: eAO4560, 2020.
Artigo em Inglês, Português | MEDLINE | ID: mdl-32321078

RESUMO

OBJECTIVE: To investigate if ICI 182,780 (fulvestrant), a selective estrogen receptor alpha/beta (ERα/ERß) antagonist, and G-1, a selective G-protein-coupled receptor (GPER) agonist, can potentially induce autophagy in breast cancer cell lines MCF-7 and SKBr3, and how G-1 affects cell viability. METHODS: Cell viability in MCF-7 and SKBr3 cells was assessed by the MTT assay. To investigate the autophagy flux, MCF-7 cells were transfected with GFP-LC3, a marker of autophagosomes, and analyzed by real-time fluorescence microscopy. MCF-7 and SKBr3 cells were incubated with acridine orange for staining of acidic vesicular organelles and analyzed by flow cytometry as an indicator of autophagy. RESULTS: Regarding cell viability in MCF-7 cells, ICI 182,780 and rapamycin, after 48 hours, led to decreased cell proliferation whereas G-1 did not change viability over the same period. The data showed that neither ICI 182,780 nor G-1 led to increased GFP-LC3 puncta in MCF-7 cells over the 4-hour observation period. The cytometry assay showed that ICI 182,780 led to a higher number of acidic vesicular organelles in MCF-7 cells. G-1, in turn, did not have this effect in any of the cell lines. In contrast, ICI 182,780 and G-1 did not decrease cell viability of SKBr3 cells or induce formation of acidic vesicular organelles, which corresponds to the final step of the autophagy process in this cell line. CONCLUSION: The effect of ICI 182,780 on increasing acidic vesicular organelles in estrogen receptor-positive breast cancer cells appears to be associated with its inhibitory effect on estrogen receptors, and GPER does notseem to be involved. Understanding these mechanisms may guide further investigations of these receptors' involvement in cellular processes of breast cancer resistance.


Assuntos
Autofagia/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Antagonistas do Receptor de Estrogênio/farmacologia , Fulvestranto/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Análise de Variância , Western Blotting , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor beta de Estrogênio/antagonistas & inibidores , Feminino , Citometria de Fluxo/métodos , Humanos , Células MCF-7 , Receptores Acoplados a Proteínas-G/análise , Reprodutibilidade dos Testes , Sirolimo/farmacologia , Fatores de Tempo , Transfecção/métodos
12.
FASEB J ; 34(5): 6008-6016, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32281695

RESUMO

The sudden outbreak of COVID-19 has led to more than seven thousand deaths. Unfortunately, there are no specific drugs available to cure this disease. Type 2 taste receptors (TAS2Rs) may play an important role in host defense mechanisms. Based on the idea of host-directed therapy (HDT), we performed a negative co-expression analysis using big data of 60 000 Affymetrix expression arrays and 5000 TCGA data sets to determine the functions of TAS2R10, which can be activated by numerous bitter substances. Excitingly, we found that the main functions of TAS2R10 involved controlling infectious diseases caused by bacteria, viruses, and parasites, suggesting that TAS2R10 is a key trigger of host defense pathways. To quickly guide the clinical treatment of 2019-nCoV, we searched currently available drugs that are agonists of TAS2Rs. We identified many cheap, available, and safe medicines, such as diphenidol, quinine, chloroquine, artemisinin, chlorpheniramine, yohimbine, and dextromethorphan, which may target the most common symptoms caused by 2019-nCoV. We suggest that a cocktail-like recipe of existing bitter drugs may help doctors to fight this catastrophic disease and that the general public may drink or eat bitter substances, such as coffee, tea, or bitter vegetables, to reduce the risk of infection.


Assuntos
Antivirais/uso terapêutico , Biologia Computacional , Infecções por Coronavirus/tratamento farmacológico , Pneumonia Viral/tratamento farmacológico , Receptores Acoplados a Proteínas-G/agonistas , Antivirais/farmacologia , Betacoronavirus , Bases de Dados Genéticas , Bases de Dados de Produtos Farmacêuticos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Pandemias , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores Acoplados a Proteínas-G/genética
13.
N Engl J Med ; 382(16): 1497-1506, 2020 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-32294346

RESUMO

BACKGROUND: An oral compound, SEP-363856, that does not act on dopamine D2 receptors but has agonist activity at trace amine-associated receptor 1 (TAAR1) and 5-hydroxytryptamine type 1A (5-HT1A) receptors, may represent a new class of psychotropic agent for the treatment of psychosis in schizophrenia. METHODS: We performed a randomized, controlled trial to evaluate the efficacy and safety of SEP-363856 in adults with an acute exacerbation of schizophrenia. The patients were randomly assigned in a 1:1 ratio to receive once-daily treatment with SEP-363856 (50 mg or 75 mg) or placebo for 4 weeks. The primary end point was the change from baseline in the total score on the Positive and Negative Symptom Scale (PANSS; range, 30 to 210; higher scores indicate more severe psychotic symptoms) at week 4. There were eight secondary end points, including the changes from baseline in the scores on the Clinical Global Impressions Severity (CGI-S) scale and the Brief Negative Symptom Scale (BNSS). RESULTS: A total of 120 patients were assigned to the SEP-363856 group and 125 to the placebo group. The mean total score on the PANSS at baseline was 101.4 in the SEP-363856 group and 99.7 in the placebo group, and the mean change at week 4 was -17.2 points and -9.7 points, respectively (least-squares mean difference, -7.5 points; 95% confidence interval, -11.9 to -3.0; P = 0.001). The reductions in the CGI-S and BNSS scores at week 4 were generally in the same direction as those for the primary outcome, but the results were not adjusted for multiple comparisons. Adverse events with SEP-363856 included somnolence and gastrointestinal symptoms; one sudden cardiac death occurred in the SEP-363856 group. The incidence of extrapyramidal symptoms and changes in the levels of lipids, glycated hemoglobin, and prolactin were similar in the trial groups. CONCLUSIONS: In this 4-week trial involving patients with an acute exacerbation of schizophrenia, SEP-363856, a non-D2-receptor-binding antipsychotic drug, resulted in a greater reduction from baseline in the PANSS total score than placebo. Longer and larger trials are necessary to confirm the effects and side effects of SEP-363856, as well as its efficacy relative to existing drug treatments for patients with schizophrenia. (Funded by Sunovion Pharmaceuticals; ClinicalTrials.gov number, NCT02969382.).


Assuntos
Antipsicóticos/uso terapêutico , Esquizofrenia/tratamento farmacológico , Doença Aguda , Administração Oral , Adulto , Antipsicóticos/efeitos adversos , Método Duplo-Cego , Esquema de Medicação , Feminino , Humanos , Análise dos Mínimos Quadrados , Masculino , Receptores de Dopamina D2 , Receptores Acoplados a Proteínas-G/agonistas , Esquizofrenia/classificação , Psicologia do Esquizofrênico , Agonistas do Receptor 5-HT1 de Serotonina/uso terapêutico , Índice de Gravidade de Doença , Resultado do Tratamento
14.
Chem Pharm Bull (Tokyo) ; 68(3): 234-243, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115530

RESUMO

Diphenhydramine, a sedating antihistamine, is an agonist of human bitter taste receptor 14 (hTAS2R14). Diphenhydramine hydrochloride (DPH) was used as a model bitter medicine to evaluate whether the umami dipeptides (Glu-Glu and Asp-Asp) and their constituent amino acids (Glu, Asp) could suppress its bitterness intensity, as measured by human gustatory sensation testing and using the artificial taste sensor. Various concentrated (0.001-5.0 mM) Glu-Glu, Asp-Asp, Glu and Asp significantly suppressed the taste sensor output of 0.5 mM DPH solution in a dose-dependent manner. The effect of umami dipeptides and their constituent amino acids was tending to be ranked as follows, Asp-Asp > Glu-Glu >> Gly-Gly, and Asp > Glu >> Gly (control) respectively. Whereas human bitterness intensity of 0.5 mM DPH solution with various concentrated (0.5, 1.0, 1.5 mM) Glu-Glu, Asp-Asp, Glu and Asp all significantly reduced bitterness intensity of 0.5 mM DPH solution even though no statistical difference was observed among four substances. The taste sensor outputs and the human gustatory sensation test results showed a significant correlation. A surface plasmon resonance study using hTAS2R14 protein and these substances suggested that the affinity of Glu-Glu, Asp-Asp, Glu and Asp for hTAS2R14 protein was greater than that of Gly-Gly or Gly. The results of docking-simulation studies involving DPH, Glu-Glu and Asp-Asp with hTAS2R14, suggested that DPH is able to bind to a space near the binding position of Glu-Glu and Asp-Asp. In conclusion, the umami dipeptides Glu-Glu and Asp-Asp, and their constituent amino acids, can all efficiently suppress the bitterness of DPH.


Assuntos
Aminoácidos/farmacologia , Dipeptídeos/farmacologia , Difenidramina/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Paladar/efeitos dos fármacos , Aminoácidos/química , Dipeptídeos/química , Difenidramina/química , Relação Dose-Resposta a Droga , Humanos , Ligantes , Modelos Moleculares , Relação Estrutura-Atividade
15.
Am J Physiol Gastrointest Liver Physiol ; 318(4): G682-G693, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32003602

RESUMO

Postprandial dyslipidemia is a common feature of insulin-resistant states and contributes to increased cardiovascular disease risk. Recently, bile acids have been recognized beyond their emulsification properties as important signaling molecules that promote energy expenditure, improve insulin sensitivity, and lower fasting lipemia. Although bile acid receptors have become novel pharmaceutical targets, their effects on postprandial lipid metabolism remain unclear. Here, we investigated the potential role of bile acids in regulation of postprandial chylomicron production and triglyceride excursion. Healthy C57BL/6 mice were given an intraduodenal infusion of taurocholic acid (TA) under fat-loaded conditions, and circulating lipids were measured. Targeting of bile acid receptors was achieved with GW4064, a synthetic agonist to the farnesoid X receptor (FXR), and deoxycholic acid (DCA), an activator of the Takeda G-protein-coupled receptor 5. TA, GW4064, and DCA treatments all lowered postprandial lipemia. FXR agonism also reduced intestinal triglyceride content and activity of microsomal triglyceride transfer protein, involved in chylomicron assembly. Importantly, TA (but not DCA) effects were largely lost in FXR knockout mice. These bile acid effects are reminiscent of the antidiabetic hormone glucagon-like peptide-1 (GLP-1). Although the GLP-1 receptor agonist exendin-4 retained its ability to acutely lower postprandial lipemia during bile acid sequestration and FXR deficiency, it did raise hepatic expression of the rate-limiting enzyme for bile acid synthesis. Bile acid signaling may be an important mechanism of controlling dietary lipid absorption, and bile acid receptors may constitute novel targets for the treatment of postprandial dyslipidemia.NEW & NOTEWORTHY We present new data suggesting potentially important roles for bile acids in regulation of postprandial lipid metabolism. Specific bile acid species, particularly secondary bile acids, were found to markedly inhibit absorption of dietary lipid and reduce postprandial triglyceride excursion. These effects appear to be mediated via bile acid receptors, farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5). Importantly, bile acid signaling may trigger glucagon-like peptide-1 (GLP-1) secretion, which may in turn mediate the marked inhibitory effects on dietary fat absorption.


Assuntos
Ácido Desoxicólico/farmacologia , Hiperlipidemias/tratamento farmacológico , Isoxazóis/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Período Pós-Prandial , Receptores Citoplasmáticos e Nucleares/agonistas , Animais , Ácidos e Sais Biliares/metabolismo , Ácidos e Sais Biliares/farmacologia , Colesterol 7-alfa-Hidroxilase/genética , Colesterol 7-alfa-Hidroxilase/metabolismo , Exenatida/farmacologia , Esvaziamento Gástrico/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Insulina/sangue , Mucosa Intestinal , Intestinos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptores Acoplados a Proteínas-G/agonistas , Ácido Taurocólico/farmacologia
16.
Nature ; 579(7797): 152-157, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32076264

RESUMO

GPR52 is a class-A orphan G-protein-coupled receptor that is highly expressed in the brain and represents a promising therapeutic target for the treatment of Huntington's disease and several psychiatric disorders1,2. Pathological malfunction of GPR52 signalling occurs primarily through the heterotrimeric Gs protein2, but it is unclear how GPR52 and Gs couple for signal transduction and whether a native ligand or other activating input is required. Here we present the high-resolution structures of human GPR52 in three states: a ligand-free state, a Gs-coupled self-activation state and a potential allosteric ligand-bound state. Together, our structures reveal that extracellular loop 2 occupies the orthosteric binding pocket and operates as a built-in agonist, conferring an intrinsically high level of basal activity to GPR523. A fully active state is achieved when Gs is coupled to GPR52 in the absence of an external agonist. The receptor also features a side pocket for ligand binding. These insights into the structure and function of GPR52 could improve our understanding of other self-activated GPCRs, enable the identification of endogenous and tool ligands, and guide drug discovery efforts that target GPR52.


Assuntos
Receptores Acoplados a Proteínas-G/química , Receptores Acoplados a Proteínas-G/metabolismo , Regulação Alostérica , Sítio Alostérico , Motivos de Aminoácidos , Sequência de Aminoácidos , Apoproteínas/agonistas , Apoproteínas/química , Apoproteínas/metabolismo , Sítios de Ligação , Microscopia Crioeletrônica , Cristalografia por Raios X , Subunidades alfa Gs de Proteínas de Ligação ao GTP/química , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/ultraestrutura , Humanos , Ligantes , Modelos Moleculares , Receptores Acoplados a Proteínas-G/agonistas , Receptores Acoplados a Proteínas-G/ultraestrutura
17.
Curr Opin Endocrinol Diabetes Obes ; 27(2): 110-114, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32073429

RESUMO

PURPOSE OF REVIEW: Numerous studies have pointed to profound nongustatory roles of tastants and the corresponding taste receptors expressed in the alimentary canal in the modulation of digestive and metabolic functions. Already in early reports, the intriguing possibility to use tastants as drug-like effectors for the treatment of metabolic diseases was raised. With this review, focusing on the most recent literature, we intend to question how close we meanwhile came to the initial promise - the use of tastants as medicines. RECENT FINDINGS: Although the enormous complexity and experimental variability of studies investigating the effects of tastants on physiological functions still has not revealed a common fundament from which subsequent therapeutic measures could be designed, more and more evidence is mounting on an involvement of taste receptors and taste signaling molecules in the maintenance and fine regulation of gastrointestinal functions and immunity. SUMMARY: Although the initial goal - using tastants to treat metabolic disorders - has, by far, not been reached, numerous promising findings suggest that dietary interventions could be devised to support conventional therapies in the future.


Assuntos
Dietoterapia/tendências , Fármacos Gastrointestinais/isolamento & purificação , Trato Gastrointestinal/metabolismo , Preparações Farmacêuticas , Receptores Acoplados a Proteínas-G/metabolismo , Paladar , Animais , Dietoterapia/métodos , Fármacos Gastrointestinais/farmacologia , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/fisiologia , Humanos , Receptores Acoplados a Proteínas-G/agonistas , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Paladar/efeitos dos fármacos , Paladar/fisiologia
18.
Sci Transl Med ; 12(528)2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996464

RESUMO

Human obesity has become a global health epidemic, with few safe and effective pharmacological therapies currently available. The systemic loss of ovarian estradiol (E2) in women after menopause greatly increases the risk of obesity and metabolic dysfunction, revealing the critical role of E2 in this setting. The salutary effects of E2 are traditionally attributed to the classical estrogen receptors ERα and ERß, with the contribution of the G protein-coupled estrogen receptor (GPER) still largely unknown. Here, we used ovariectomy- and diet-induced obesity (DIO) mouse models to evaluate the preclinical activity of GPER-selective small-molecule agonist G-1 (also called Tespria) against obesity and metabolic dysfunction. G-1 treatment of ovariectomized female mice (a model of postmenopausal obesity) reduced body weight and improved glucose homeostasis without changes in food intake, fuel source usage, or locomotor activity. G-1-treated female mice also exhibited increased energy expenditure, lower body fat content, and reduced fasting cholesterol, glucose, insulin, and inflammatory markers but did not display feminizing effects on the uterus (imbibition) or beneficial effects on bone health. G-1 treatment of DIO male mice did not elicit weight loss but prevented further weight gain and improved glucose tolerance, indicating that G-1 improved glucose homeostasis independently of its antiobesity effects. However, in ovariectomized DIO female mice, G-1 continued to elicit weight loss, reflecting possible sex differences in the mechanisms of G-1 action. In conclusion, this work demonstrates that GPER-selective agonism is a viable therapeutic approach against obesity, diabetes, and associated metabolic abnormalities in multiple preclinical male and female models.


Assuntos
Diabetes Mellitus/tratamento farmacológico , Obesidade/tratamento farmacológico , Receptores Acoplados a Proteínas-G/agonistas , Tecido Adiposo/patologia , Adiposidade/efeitos dos fármacos , Animais , Respiração Celular , Modelos Animais de Doenças , Metabolismo Energético , Estrogênios/deficiência , Feminino , Genes Mitocondriais , Glucose/metabolismo , Homeostase , Inflamação/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/genética , Obesidade/complicações , Ovariectomia , Receptores Estrogênicos/metabolismo , Receptores Acoplados a Proteínas-G/metabolismo , Resultado do Tratamento , Regulação para Cima , Ganho de Peso
19.
Am J Physiol Gastrointest Liver Physiol ; 318(3): G554-G573, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31984784

RESUMO

Bile acid synthesis is the most significant pathway for catabolism of cholesterol and for maintenance of whole body cholesterol homeostasis. Bile acids are physiological detergents that absorb, distribute, metabolize, and excrete nutrients, drugs, and xenobiotics. Bile acids also are signal molecules and metabolic integrators that activate nuclear farnesoid X receptor (FXR) and membrane Takeda G protein-coupled receptor 5 (TGR5; i.e., G protein-coupled bile acid receptor 1) to regulate glucose, lipid, and energy metabolism. The gut-to-liver axis plays a critical role in the transformation of primary bile acids to secondary bile acids, in the regulation of bile acid synthesis to maintain composition within the bile acid pool, and in the regulation of metabolic homeostasis to prevent hyperglycemia, dyslipidemia, obesity, and diabetes. High-fat and high-calorie diets, dysbiosis, alcohol, drugs, and disruption of sleep and circadian rhythms cause metabolic diseases, including alcoholic and nonalcoholic fatty liver diseases, obesity, diabetes, and cardiovascular disease. Bile acid-based drugs that target bile acid receptors are being developed for the treatment of metabolic diseases of the liver.


Assuntos
Ácidos e Sais Biliares/metabolismo , Fígado Gorduroso/metabolismo , Fígado/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores Acoplados a Proteínas-G/metabolismo , Animais , Fígado Gorduroso/diagnóstico , Fígado Gorduroso/tratamento farmacológico , Fármacos Gastrointestinais/uso terapêutico , Humanos , Fígado/efeitos dos fármacos , Fígado/patologia , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Acoplados a Proteínas-G/agonistas , Transdução de Sinais
20.
Eur J Med Chem ; 188: 112017, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31926470

RESUMO

A series of xanthine compounds derived from the previous hit 20i with modification on the terminal side chain was discovered through ring formation strategy. Systematic optimization of the compounds with rigid heterocycles in the hydrophobic side chain led to the new lead compound HBK001 (21h) with the improved DPP-IV inhibition and moderate GPR119 agonism activity in vitro. As a continuing work to further study the PK and PD profiles, 21h and its hydrochloride (22) were synthesized on grams scale and evaluated on the ADME/T and oral glucose tolerance test (OGTT) in ICR mice. Compound 22 showed the improved bioavailability and blood glucose-lowering effect in vivo compared to its free base 21h probably attributed to its improved solubility and permeability. The preliminary toxicity studies on compound 22 exhibited that the result of mini-Ames was negative and the preliminary acute toxicity LD50 in mice was above 1.5 g/kg, while it showed moderate inhibition on hERG channel with IC50 4.9 µM maybe due to its high lipophilicity. These findings will be useful for the future drug design for more potent and safer dual ligand targeting DPP-IV and GPR119 for the treatment of diabetes.


Assuntos
Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Hipoglicemiantes/farmacologia , Piperidinas/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Xantina/farmacologia , Animais , Inibidores da Dipeptidil Peptidase IV/síntese química , Inibidores da Dipeptidil Peptidase IV/química , Relação Dose-Resposta a Droga , Teste de Tolerância a Glucose , Humanos , Hipoglicemiantes/síntese química , Hipoglicemiantes/química , Camundongos , Camundongos Endogâmicos ICR , Microssomos Hepáticos/química , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Piperidinas/síntese química , Piperidinas/química , Receptores Acoplados a Proteínas-G/metabolismo , Relação Estrutura-Atividade , Xantina/síntese química , Xantina/química
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