Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros

Base de dados
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Immunity ; 56(11): 2602-2620.e10, 2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-37967532

RESUMO

Human cytomegalovirus (HCMV) can cause severe diseases in fetuses, newborns, and immunocompromised individuals. Currently, no vaccines are approved, and treatment options are limited. Here, we analyzed the human B cell response of four HCMV top neutralizers from a cohort of 9,000 individuals. By single-cell analyses of memory B cells targeting the pentameric and trimeric HCMV surface complexes, we identified vulnerable sites on the shared gH/gL subunits as well as complex-specific subunits UL128/130/131A and gO. Using high-resolution cryogenic electron microscopy, we revealed the structural basis of the neutralization mechanisms of antibodies targeting various binding sites. Moreover, we identified highly potent antibodies that neutralized a broad spectrum of HCMV strains, including primary clinical isolates, that outperform known antibodies used in clinical trials. Our study provides a deep understanding of the mechanisms of HCMV neutralization and identifies promising antibody candidates to prevent and treat HCMV infection.


Assuntos
Citomegalovirus , Proteínas do Envelope Viral , Recém-Nascido , Humanos , Glicoproteínas de Membrana , Anticorpos Neutralizantes , Células B de Memória , Anticorpos Antivirais , Análise de Célula Única
2.
Proc Natl Acad Sci U S A ; 119(50): e2215333119, 2022 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-36469765

RESUMO

Efforts to decrease the adverse effects of nuclear receptor (NR) drugs have yielded experimental agonists that produce better outcomes in mice. Some of these agonists have been shown to cause different, not just less intense, on-target transcriptomic effects; however, a structural explanation for such agonist-specific effects remains unknown. Here, we show that partial agonists of the NR peroxisome proliferator-associated receptor γ (PPARγ), which induce better outcomes in mice compared to clinically utilized type II diabetes PPARγ-binding drugs thiazolidinediones (TZDs), also favor a different group of coactivator peptides than the TZDs. We find that PPARγ full agonists can also be biased relative to each other in terms of coactivator peptide binding. We find differences in coactivator-PPARγ bonding between the coactivator subgroups which allow agonists to favor one group of coactivator peptides over another, including differential bonding to a C-terminal residue of helix 4. Analysis of all available NR-coactivator structures indicates that such differential helix 4 bonding persists across other NR-coactivator complexes, providing a general structural mechanism of biased agonism for many NRs. Further work will be necessary to determine if such bias translates into altered coactivator occupancy and physiology in cells.


Assuntos
Diabetes Mellitus Tipo 2 , Tiazolidinedionas , Camundongos , Animais , PPAR gama/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Tiazolidinedionas/farmacologia , Ligação Proteica , Peptídeos/farmacologia , Peptídeos/metabolismo , Ligantes
3.
Mol Pharmacol ; 2024 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-39443155

RESUMO

Biased signaling and ligand bias, often termed functional selectivity or selective nuclear receptor modulation, have been reported for nuclear receptor partial agonists over the past 20 years. Whether signaling differences produced by partial agonists result from less intense modulation, off-target effects, or biased signaling remains unclear. A commonly postulated mechanism for biased signaling is coactivator favoritism, where agonists induce different coactivator recruitment profiles. We find that both GW1929 (full agonist) and MRL24 (partial agonist) favor recruitment of 100-300 residue regions from S-motif coactivators compared to a reference full agonist (rosiglitazone), yielding 95% bias value confidence intervals of 0.05-0.17 and 0.29-0.38 respectively. Calculations based on these data indicate that GW1929 and MRL24 would induce 30-60% higher S-motif coactivator occupancy at the receptor compared to rosiglitazone. We compare the transcriptional effects of these same three ligands on human adipocytes using RNA sequencing and exploratory KEGG pathway analysis. Only 50% (rosiglitazone) and 77% (GW1929) of all gene expression changes are shared between these full agonists after 3 hours of exposure. After 24 hours of exposure, 13/98 KEGG pathways appear more intensely modulated by rosiglitazone than GW1929 (e.g., 95% CI of bias in the regulation of lipolysis in adipocytes pathway is 0.03-0.09), despite similar signaling for the remaining 85 affected pathways. Similarly, rosiglitazone has an unusually large effect on several lipid metabolism-related pathways compared to the partial agonist MRL24. These data indicate that nuclear receptor full and partial agonists can induce biased signaling, likely through differences in coactivator recruitment. Significance Statement Many nuclear receptor partial agonists cause fewer adverse effects and similar efficacy compared to full agonists, potentially by inducing biased agonism. Our data support the idea that partial agonists, and a full agonist, of the nuclear receptor Peroxisome proliferator-activated receptor gamma (PPARγ) are biased agonists, causing different signaling by inducing PPARγ to favor different coactivators. These data indicate that biased agonism can occur in nuclear receptors and should be considered in efforts to develop improved nuclear receptor-targeted drugs.

4.
Nat Commun ; 10(1): 5825, 2019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31862968

RESUMO

The repressive states of nuclear receptors (i.e., apo or bound to antagonists or inverse agonists) are poorly defined, despite the fact that nuclear receptors are a major drug target. Most ligand bound structures of nuclear receptors, including peroxisome proliferator-activated receptor γ (PPARγ), are similar to the apo structure. Here we use NMR, accelerated molecular dynamics and hydrogen-deuterium exchange mass spectrometry to define the PPARγ structural ensemble. We find that the helix 3 charge clamp positioning varies widely in apo and is stabilized by efficacious ligand binding. We also reveal a previously undescribed mechanism for inverse agonism involving an omega loop to helix switch which induces disruption of a tripartite salt-bridge network. We demonstrate that ligand binding can induce multiple structurally distinct repressive states. One state recruits peptides from two different corepressors, while another recruits just one, providing structural evidence of ligand bias in a nuclear receptor.


Assuntos
Proteínas Correpressoras/metabolismo , PPAR gama/metabolismo , Peptídeos/metabolismo , Anilidas/farmacologia , Benzamidas/farmacologia , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/genética , Espectrometria de Massa com Troca Hidrogênio-Deutério , Ligantes , Espectroscopia de Ressonância Magnética , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , PPAR gama/agonistas , PPAR gama/antagonistas & inibidores , PPAR gama/ultraestrutura , Conformação Proteica em alfa-Hélice/efeitos dos fármacos , Conformação Proteica em alfa-Hélice/genética , Piridinas/farmacologia , Rosiglitazona/farmacologia
5.
Nat Commun ; 9(1): 4687, 2018 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-30409975

RESUMO

Small chemical modifications can have significant effects on ligand efficacy and receptor activity, but the underlying structural mechanisms can be difficult to predict from static crystal structures alone. Here we show how a simple phenyl-to-pyridyl substitution between two common covalent orthosteric ligands targeting peroxisome proliferator-activated receptor (PPAR) gamma converts a transcriptionally neutral antagonist (GW9662) into a repressive inverse agonist (T0070907) relative to basal cellular activity. X-ray crystallography, molecular dynamics simulations, and mutagenesis coupled to activity assays reveal a water-mediated hydrogen bond network linking the T0070907 pyridyl group to Arg288 that is essential for corepressor-selective inverse agonism. NMR spectroscopy reveals that PPARγ exchanges between two long-lived conformations when bound to T0070907 but not GW9662, including a conformation that prepopulates a corepressor-bound state, priming PPARγ for high affinity corepressor binding. Our findings demonstrate that ligand engagement of Arg288 may provide routes for developing corepressor-selective repressive PPARγ ligands.


Assuntos
Proteínas Correpressoras/metabolismo , PPAR gama/agonistas , PPAR gama/química , Células 3T3-L1 , Anilidas/química , Anilidas/farmacologia , Animais , Benzamidas/química , Benzamidas/farmacologia , Agonismo Inverso de Drogas , Células HEK293 , Humanos , Ligação de Hidrogênio , Ligantes , Espectroscopia de Ressonância Magnética , Camundongos , Mutagênese , Conformação Proteica , Piridinas/química , Piridinas/farmacologia , Água/química
6.
Nat Commun ; 9(1): 1794, 2018 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-29728618

RESUMO

The nuclear receptor ligand-binding domain (LBD) is a highly dynamic entity. Crystal structures have defined multiple low-energy LBD structural conformations of the activation function-2 (AF-2) co-regulator-binding surface, yet it remains unclear how ligand binding influences the number and population of conformations within the AF-2 structural ensemble. Here, we present a nuclear receptor co-regulator-binding surface structural ensemble in solution, viewed through the lens of fluorine-19 (19F) nuclear magnetic resonance (NMR) and molecular simulations, and the response of this ensemble to ligands, co-regulator peptides and heterodimerization. We correlate the composition of this ensemble with function in peroxisome proliferator-activated receptor-γ (PPARγ) utilizing ligands of diverse efficacy in co-regulator recruitment. While the co-regulator surface of apo PPARγ and partial-agonist-bound PPARγ is characterized by multiple thermodynamically accessible conformations, the full and inverse-agonist-bound PPARγ co-regulator surface is restricted to a few conformations which favor coactivator or corepressor binding, respectively.


Assuntos
Simulação de Dinâmica Molecular , PPAR gama/química , Peptídeos/química , Conformação Proteica , Sequência de Aminoácidos , Sítios de Ligação , Humanos , Ligantes , Espectroscopia de Ressonância Magnética , PPAR gama/agonistas , PPAR gama/metabolismo , Peptídeos/metabolismo , Ligação Proteica , Multimerização Proteica , Termodinâmica
7.
J Ethnopharmacol ; 197: 92-100, 2017 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-27473605

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Bacopa monnieri (L) Wettst (common name, bacopa) is a medicinal plant used in Ayurveda, the traditional system of medicine of India, as a nootropic. It is considered to be a "medhya rasayana", an herb that sharpens the mind and the intellect. Bacopa is an important ingredient in many Ayurvedic herbal formulations designed to treat conditions such as memory loss, anxiety, poor cognition and loss of concentration. It has also been used in Ayurveda to treat inflammatory conditions such as arthritis. In modern biomedical studies, bacopa has been shown in animal models to inhibit the release of the pro-inflammatory cytokines TNF-α and IL-6. However, less is known regarding the anti-inflammatory activity of Bacopa in the brain. AIM OF THE STUDY: The current study examines the ability of Bacopa to inhibit the release of pro-inflammatory cytokines from microglial cells, the immune cells of the brain that participate in inflammation in the CNS. The effect of Bacopa on signaling enzymes associated with CNS inflammatory pathways was also studied. MATERIALS AND METHODS: Various extracts of Bacopa were prepared and examined in the N9 microglial cell line in order to determine if they inhibited the release of the proinflammatory cytokines TNF-α and IL-6. Extracts were also tested in cell free assays as inhibitors of caspase-1 and matrix metalloproteinase-3 (enzymes associated with inflammation) and caspase-3, which has been shown to cleave protein Tau, an early event in the development of Alzheimer's disease. RESULTS: The tea, infusion, and alkaloid extracts of bacopa, as well as Bacoside A significantly inhibited the release of TNF-α and IL-6 from activated N9 microglial cells in vitro. In addition, the tea, infusion, and alkaloid extracts of Bacopa effectively inhibited caspase 1 and 3, and matrix metalloproteinase-3 in the cell free assay. CONCLUSIONS: Bacopa inhibits the release of inflammatory cytokines from microglial cells and inhibits enzymes associated with inflammation in the brain. Thus, Bacopa can limit inflammation in the CNS, and offers a promising source of novel therapeutics for the treatment of many CNS disorders.


Assuntos
Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Bacopa/química , Encéfalo/efeitos dos fármacos , Inflamação/tratamento farmacológico , Extratos Vegetais/farmacologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Encéfalo/metabolismo , Caspase 1/metabolismo , Caspase 3/metabolismo , Linhagem Celular , Inflamação/metabolismo , Interleucina-6/metabolismo , Metaloproteinase 3 da Matriz/metabolismo , Ayurveda , Camundongos , Nootrópicos/química , Nootrópicos/farmacologia , Extratos Vegetais/química , Plantas Medicinais/química , Fator de Necrose Tumoral alfa/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA