RESUMO
Small molecule neurotensin receptor 1 (NTSR1) agonists have been pursued for more than 40 years as potential therapeutics for psychiatric disorders, including drug addiction. Clinical development of NTSR1 agonists has, however, been precluded by their severe side effects. NTSR1, a G protein-coupled receptor (GPCR), signals through the canonical activation of G proteins and engages ß-arrestins to mediate distinct cellular signaling events. Here, we characterize the allosteric NTSR1 modulator SBI-553. This small molecule not only acts as a ß-arrestin-biased agonist but also extends profound ß-arrestin bias to the endogenous ligand by selectively antagonizing G protein signaling. SBI-553 shows efficacy in animal models of psychostimulant abuse, including cocaine self-administration, without the side effects characteristic of balanced NTSR1 agonism. These findings indicate that NTSR1 G protein and ß-arrestin activation produce discrete and separable physiological effects, thus providing a strategy to develop safer GPCR-targeting therapeutics with more directed pharmacological action.
Assuntos
Comportamento Aditivo/metabolismo , Receptores de Neurotensina/metabolismo , beta-Arrestinas/metabolismo , Regulação Alostérica/efeitos dos fármacos , Regulação Alostérica/fisiologia , Animais , Comportamento Aditivo/tratamento farmacológico , Linhagem Celular , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Bibliotecas de Moléculas Pequenas/farmacologiaRESUMO
Small-molecule probes can illuminate biological processes and aid in the assessment of emerging therapeutic targets by perturbing biological systems in a manner distinct from other experimental approaches. Despite the tremendous promise of chemical tools for investigating biology and disease, small-molecule probes were unavailable for most targets and pathways as recently as a decade ago. In 2005, the NIH launched the decade-long Molecular Libraries Program with the intent of innovating in and broadening access to small-molecule science. This Perspective describes how novel small-molecule probes identified through the program are enabling the exploration of biological pathways and therapeutic hypotheses not otherwise testable. These experiences illustrate how small-molecule probes can help bridge the chasm between biological research and the development of medicines but also highlight the need to innovate the science of therapeutic discovery.
Assuntos
Descoberta de Drogas , Bibliotecas de Moléculas Pequenas , Animais , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Ensaios de Triagem em Larga Escala , Humanos , National Institutes of Health (U.S.) , Estados UnidosRESUMO
The NTSR1 neurotensin receptor (NTSR1) is a G protein-coupled receptor (GPCR) found in the brain and peripheral tissues with neurotensin (NTS) being its endogenous peptide ligand. In the brain, NTS modulates dopamine neuronal activity, induces opioid-independent analgesia, and regulates food intake. Recent studies indicate that biasing NTSR1 toward ß-arrestin signaling can attenuate the actions of psychostimulants and other drugs of abuse. Here, we provide the cryoEM structures of NTSR1 ternary complexes with heterotrimeric Gq and GoA with and without the brain-penetrant small-molecule SBI-553. In functional studies, we discovered that SBI-553 displays complex allosteric actions exemplified by negative allosteric modulation for G proteins that are Gα subunit selective and positive allosteric modulation and agonism for ß-arrestin translocation at NTSR1. Detailed structural analysis of the allosteric binding site illuminated the structural determinants for biased allosteric modulation of SBI-553 on NTSR1.
Assuntos
Neurotensina , Receptores de Neurotensina , Receptores de Neurotensina/química , Receptores de Neurotensina/metabolismo , Neurotensina/metabolismo , Transdução de Sinais , Peptídeos/metabolismo , beta-Arrestinas/metabolismoRESUMO
In Plasmodium, the first two and rate-limiting enzymes of the pentose phosphate pathway, glucose 6-phosphate dehydrogenase (G6PD) and the 6-phosphogluconolactonase, are bifunctionally fused to a unique enzyme named GluPho, differing structurally and mechanistically from the respective human orthologs. Consistent with the enzyme's essentiality for malaria parasite proliferation and propagation, human G6PD deficiency has immense impact on protection against severe malaria, making PfGluPho an attractive antimalarial drug target. Herein we report on the optimized lead compound N-(((2R,4S)-1-cyclobutyl-4-hydroxypyrrolidin-2-yl)methyl)-6-fluoro-4-methyl-11-oxo-10,11-dihydrodibenzo[b,f][1,4]thiazepine-8-carboxamide (SBI-0797750), a potent and fully selective PfGluPho inhibitor with robust nanomolar activity against recombinant PfGluPho, PvG6PD, and P. falciparum blood-stage parasites. Mode-of-action studies have confirmed that SBI-0797750 disturbs the cytosolic glutathione-dependent redox potential, as well as the cytosolic and mitochondrial H2O2 homeostasis of P. falciparum blood stages, at low nanomolar concentrations. Moreover, SBI-0797750 does not harm red blood cell (RBC) integrity and phagocytosis and thus does not promote anemia. SBI-0797750 is therefore a very promising antimalarial lead compound.
Assuntos
Antimaláricos , Deficiência de Glucosefosfato Desidrogenase , Malária Falciparum , Malária Vivax , Malária , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Hidrolases de Éster Carboxílico , Glucose/metabolismo , Glucosefosfato Desidrogenase/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Malária Falciparum/tratamento farmacológico , Malária Vivax/tratamento farmacológico , Fosfatos , Plasmodium falciparum/metabolismo , Plasmodium vivaxRESUMO
Zika virus (ZIKV) is a mosquito-borne pathogen classified by the World Health Organization (WHO) as a public health emergency of international concern in 2016, and it is still identified as a priority disease. Although most infected individuals are asymptomatic or show mild symptoms, a risk of neurologic complications is associated with infection in adults. Additionally, infection during pregnancy is directly linked to microcephaly and other congenital malformations. Since there are no currently available vaccines or approved therapeutics for this virus, there is a critical unmet need in developing treatments to prevent future ZIKV outbreaks. Toward this end, we performed a large-scale cell-based high-content screen of 51,520 chemical compounds to identify potential antiviral drug candidates. The compound (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) was found to inhibit replication of multiple ZIKV strains and in different cell systems. SBI-0090799 did not affect viral entry or RNA translation but suppressed RNA replication by preventing the formation of the membranous replication compartment. Selection of drug-resistant viruses identified single-amino-acid substitutions in the N-terminal region of nonstructural protein NS4A, arguing this is the likely drug target. These resistance mutations rescued viral RNA replication and restored the formation of the membranous replication compartment. This mechanism of action is similar to clinically approved NS5A inhibitors for hepatitis C virus (HCV). Taken together, SBI-0090799 represents a promising lead candidate for the development of an antiviral treatment against ZIKV infection for the mitigation of severe complications and potential resurgent outbreaks of the virus. IMPORTANCE This study describes the elucidation of (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) as a selective and potent inhibitor of Zika virus (ZIKV) replication using a high-throughput screening approach. Mapping and resistance studies, supported by electron microscopy observations, indicate that the small molecule is functioning through inhibition of NS4A-mediated formation of ZIKV replication compartments in the endoplasmic reticulum (ER). Intriguingly, this defines a novel nonenzymatic target and chemical matter for the development of a new class of ZIKV antivirals. Moreover, chemical modulation affecting this nonstructural protein mirrors the identification and development of hepatitis C virus (HCV) NS5A inhibitor daclatasvir and its derivatives, similarly interfering with the formation of the viral replication compartment and also targeting a protein with no enzymatic activity, which have been part of a curative strategy for HCV.
Assuntos
Antivirais/farmacologia , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Replicação Viral/efeitos dos fármacos , Infecção por Zika virus/tratamento farmacológico , Zika virus/efeitos dos fármacos , Animais , Astrócitos , Chlorocebus aethiops , Células Dendríticas , Células HEK293 , Humanos , Cultura Primária de Células , Células Vero , Compartimentos de Replicação Viral/efeitos dos fármacosRESUMO
BACKGROUND: The BCL2 inhibitor venetoclax has shown efficacy in several hematologic malignancies, with the greatest response rates in indolent blood cancers such as chronic lymphocytic leukaemia. There is a lower response rate to venetoclax monotherapy in diffuse large B-cell lymphoma (DLBCL). METHODS: We tested inhibitors of cap-dependent mRNA translation for the ability to sensitise DLBCL and mantle cell lymphoma (MCL) cells to apoptosis by venetoclax. We compared the mTOR kinase inhibitor (TOR-KI) MLN0128 with SBI-756, a compound targeting eukaryotic translation initiation factor 4G1 (eIF4G1), a scaffolding protein in the eIF4F complex. RESULTS: Treatment of DLBCL and MCL cells with SBI-756 synergised with venetoclax to induce apoptosis in vitro, and enhanced venetoclax efficacy in vivo. SBI-756 prevented eIF4E-eIF4G1 association and cap-dependent translation without affecting mTOR substrate phosphorylation. In TOR-KI-resistant DLBCL cells lacking eIF4E binding protein-1, SBI-756 still sensitised to venetoclax. SBI-756 selectively reduced translation of mRNAs encoding ribosomal proteins and translation factors, leading to a reduction in protein synthesis rates in sensitive cells. When normal lymphocytes were treated with SBI-756, only B cells had reduced viability, and this correlated with reduced protein synthesis. CONCLUSIONS: Our data highlight a novel combination for treatment of aggressive lymphomas, and establishes its efficacy and selectivity using preclinical models.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Fator de Iniciação 4E em Eucariotos/antagonistas & inibidores , Linfoma de Células B/tratamento farmacológico , Terapia de Alvo Molecular , Animais , Apoptose , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Proliferação de Células , Feminino , Humanos , Lactamas/administração & dosagem , Linfoma de Células B/metabolismo , Linfoma de Células B/patologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Quinolonas/administração & dosagem , Sulfonamidas/administração & dosagem , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the rate-limiting step of the NAD+ salvage pathway. Since NAD+ plays a pivotal role in many biological processes including metabolism and aging, activation of NAMPT is an attractive therapeutic target for treatment of diverse array of diseases. Herein, we report the continued optimization of novel urea-containing derivatives which were identified as potent NAMPT activators. Early optimization of HTS hits afforded compound 12, with a triazolopyridine core, as a lead compound. CYP direct inhibition (DI) was identified as an issue of concern, and was resolved through modulation of lipophilicity to culminate in 1-[2-(1-methyl-1H-pyrazol-5-yl)-[1,2,4]triazolo[1,5-a]pyridin-6-yl]-3-(pyridin-4-ylmethyl)urea (21), which showed potent NAMPT activity accompanied with attenuated CYP DI towards multiple CYP isoforms.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Citocinas/metabolismo , Descoberta de Drogas , Inibidores Enzimáticos/farmacologia , Nicotinamida Fosforribosiltransferase/metabolismo , Ureia/farmacologia , Animais , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Estrutura Molecular , Relação Estrutura-Atividade , Ureia/análogos & derivados , Ureia/químicaRESUMO
NAD+ is a crucial cellular factor that plays multifaceted roles in wide ranging biological processes. Low levels of NAD+ have been linked to numerous diseases including metabolic disorders, cardiovascular disease, neurodegeneration, and muscle wasting disorders. A novel strategy to boost NAD+ is to activate nicotinamide phosphoribosyltransferase (NAMPT), the putative rate-limiting step in the NAD+ salvage pathway. We previously showed that NAMPT activators increase NAD+ levels in vitro and in vivo. Herein we describe the optimization of our NAMPT activator prototype (SBI-0797812) leading to the identification of 1-(4-((4-chlorophenyl)sulfonyl)phenyl)-3-(oxazol-5-ylmethyl)urea (34) that showed far more potent NAMPT activation and improved oral bioavailability.
Assuntos
Citocinas/metabolismo , Nicotinamida Fosforribosiltransferase/metabolismo , Ureia/farmacologia , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Relação Estrutura-Atividade , Ureia/análogos & derivados , Ureia/químicaRESUMO
Medial arterial calcification (MAC) is a major complication of chronic kidney disease (CKD) and an indicator of poor prognosis. Aortic overexpression of tissue-nonspecific alkaline phosphatase (TNAP) accelerates MAC formation. The present study aimed to assess whether a TNAP inhibitor, SBI-425, protects against MAC and improves survival probability in a CKD-mineral and bone disorder (MBD) mouse model. CKD-MBD mice were divided in three groups: vehicle, SBI-10, and SBI-30. They were fed a 0.2% adenine and 0.8% phosphorus diet from 14 to 20 weeks of age to induce CKD, followed by a high-phosphorus (0.2% adenine and 1.8% phosphorus) diet for another 6 weeks. At 14-20 weeks of age, mice in the SBI-10 and SBI-30 groups were given 10 and 30 mg/kg SBI-425 by gavage once a day, respectively, while vehicle-group mice were given distilled water as vehicle. Control mice were fed a standard chow (0.8% phosphorus) between the ages of 8 and 20 weeks. Computed tomography imaging, histology, and aortic tissue calcium content revealed that, compared to vehicle animals, SBI-425 nearly halted the formation of MAC. Mice in the control, SBI-10 and SBI-30 groups exhibited 100% survival, which was significantly better than vehicle-treated mice (57.1%). Aortic mRNA expression of Alpl, encoding TNAP, as well as plasma and aortic tissue TNAP activity, were suppressed by SBI-425 administration, whereas plasma pyrophosphate increased. We conclude that a TNAP inhibitor successfully protected the vasculature from MAC and improved survival rate in a mouse CKD-MBD model, without causing any adverse effects on normal skeletal formation and residual renal function. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Fosfatase Alcalina/antagonistas & inibidores , Aorta/efeitos dos fármacos , Doenças da Aorta/prevenção & controle , Distúrbio Mineral e Ósseo na Doença Renal Crônica/tratamento farmacológico , Inibidores Enzimáticos/farmacologia , Niacinamida/análogos & derivados , Sulfonamidas/farmacologia , Calcificação Vascular/prevenção & controle , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Animais , Aorta/enzimologia , Aorta/patologia , Doenças da Aorta/enzimologia , Doenças da Aorta/etiologia , Doenças da Aorta/patologia , Distúrbio Mineral e Ósseo na Doença Renal Crônica/complicações , Distúrbio Mineral e Ósseo na Doença Renal Crônica/enzimologia , Distúrbio Mineral e Ósseo na Doença Renal Crônica/patologia , Modelos Animais de Doenças , Regulação da Expressão Gênica , Masculino , Camundongos Endogâmicos C57BL , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/enzimologia , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/enzimologia , Miócitos de Músculo Liso/patologia , Niacinamida/farmacologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/enzimologia , Osteoblastos/patologia , Fatores de Tempo , Calcificação Vascular/enzimologia , Calcificação Vascular/etiologia , Calcificação Vascular/patologiaRESUMO
Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the rate-limiting step of the nicotinamide adenine dinucleotide (NAD+) salvage pathway. Because NAD+ plays a pivotal role in energy metabolism and boosting NAD+ has positive effects on metabolic regulation, activation of NAMPT is an attractive therapeutic approach for the treatment of various diseases, including type 2 diabetes and obesity. Herein we report the discovery of 1-(2-phenyl-1,3-benzoxazol-6-yl)-3-(pyridin-4-ylmethyl)urea 12c (DS68702229), which was identified as a potent NAMPT activator. Compound 12c activated NAMPT, increased cellular NAD+ levels, and exhibited an excellent pharmacokinetic profile in mice after oral administration. Oral administration of compound 12c to high-fat diet-induced obese mice decreased body weight. These observations indicate that compound 12c is a promising anti-obesity drug candidate.
Assuntos
Fármacos Antiobesidade/síntese química , Nicotinamida Fosforribosiltransferase/metabolismo , Bibliotecas de Moléculas Pequenas/síntese química , Ureia/síntese química , Animais , Fármacos Antiobesidade/administração & dosagem , Fármacos Antiobesidade/farmacocinética , Peso Corporal/efeitos dos fármacos , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Masculino , Camundongos Obesos , NAD/metabolismo , Obesidade/metabolismo , Bibliotecas de Moléculas Pequenas/administração & dosagem , Bibliotecas de Moléculas Pequenas/farmacocinética , Relação Estrutura-Atividade , Ureia/administração & dosagem , Ureia/farmacocinéticaRESUMO
Sepsis is a host response to systemic inflammation and infection that may lead to multi-organ dysfunction and eventual death. While acute brain dysfunction is common among all sepsis patients, chronic neurological impairment is prevalent among sepsis survivors. The brain microvasculature has emerged as a major determinant of sepsis-associated brain dysfunction, yet the mechanisms that underlie its associated neuroimmune perturbations and behavioral deficits are not well understood. An emerging body of data suggests that inhibition of tissue-nonspecific alkaline phosphatase (TNAP) enzyme activity in cerebral microvessels may be associated with changes in endothelial cell barrier integrity. The objective of this study was to elucidate the connection between alterations in cerebrovascular TNAP enzyme activity and brain microvascular dysfunction in late sepsis. We hypothesized that the disruption of TNAP enzymatic activity in cerebral microvessels would be coupled to the sustained loss of brain microvascular integrity, elevated neuroinflammatory responses, and behavioral deficits. Male mice were subjected to cecal ligation and puncture (CLP), a model of experimental sepsis, and assessed up to seven days post-sepsis. All mice were observed daily for sickness behavior and underwent behavioral testing. Our results showed a significant decrease in brain microvascular TNAP enzyme activity in the somatosensory cortex and spinal cord of septic mice but not in the CA1 and CA3 hippocampal regions. Furthermore, we showed that loss of cerebrovascular TNAP enzyme activity was coupled to a loss of claudin-5 and increased perivascular IgG infiltration in the somatosensory cortex. Analyses of whole brain myeloid and T-lymphoid cell populations also revealed a persistent elevation of infiltrating leukocytes, which included both neutrophil and monocyte myeloid derived suppressor cells (MDSCs). Regional analyses of the somatosensory cortex, hippocampus, and spinal cord revealed significant astrogliosis and microgliosis in the cortex and spinal cord of septic mice that was accompanied by significant microgliosis in the CA1 and CA3 hippocampal regions. Assessment of behavioral deficits revealed no changes in learning and memory or evoked locomotion. However, the hot plate test uncovered a novel anti-nociceptive phenotype in our septic mice, and we speculate that this phenotype may be a consequence of sustained GFAP astrogliosis and loss of TNAP activity in the somatosensory cortex and spinal cord of septic mice. Taken together, these results demonstrate that the loss of TNAP enzyme activity in cerebral microvessels during late sepsis is coupled to sustained neuroimmune dysfunction which may underlie, in part, the chronic neurological impairments observed in sepsis survivors.
Assuntos
Fosfatase Alcalina/metabolismo , Encéfalo/irrigação sanguínea , Inflamação/complicações , Inflamação/enzimologia , Microvasos/enzimologia , Sepse/complicações , Sepse/psicologia , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Linhagem Celular , Modelos Animais de Doenças , Humanos , Inflamação/psicologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Sepse/enzimologiaRESUMO
The chemokine system plays an important role in mediating a proinflammatory microenvironment for tumor growth in hepatocellular carcinoma (HCC). The CXCR6 receptor and its natural ligand CXCL16 are expressed at high levels in HCC cell lines and tumor tissues and receptor expression correlates with increased neutrophils in these tissues contributing to poor prognosis in patients. Availability of pharmacologcal tools targeting the CXCR6/CXCL16 axis are needed to elucidate the mechanism whereby neutrophils are affected in the tumor environment. We report the discovery of a series of small molecules with an exo-[3.3.1]azabicyclononane core. Our lead compound 81 is a potent (EC50 = 40 nM) and selective orally bioavailable small molecule antagonist of human CXCR6 receptor signaling that significantly decreases tumor growth in a 30-day mouse xenograft model of HCC.
Assuntos
Receptores CXCR6/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/química , Animais , Compostos Azabicíclicos/química , Compostos Azabicíclicos/metabolismo , Compostos Azabicíclicos/farmacologia , Compostos Azabicíclicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Feminino , Humanos , Concentração Inibidora 50 , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/patologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Receptores CXCR6/metabolismo , Transdução de Sinais/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Bibliotecas de Moléculas Pequenas/uso terapêutico , Relação Estrutura-Atividade , Transplante HeterólogoRESUMO
The proteasome is a vital cellular machine that maintains protein homeostasis, which is of particular importance in multiple myeloma and possibly other cancers. Targeting of proteasome 20S peptidase activity with bortezomib and carfilzomib has been widely used to treat myeloma. However, not all patients respond to these compounds, and those who do eventually suffer relapse. Therefore, there is an urgent and unmet need to develop new drugs that target proteostasis through different mechanisms. We identified quinoline-8-thiol (8TQ) as a first-in-class inhibitor of the proteasome 19S subunit Rpn11. A derivative of 8TQ, capzimin, shows >5-fold selectivity for Rpn11 over the related JAMM proteases and >2 logs selectivity over several other metalloenzymes. Capzimin stabilized proteasome substrates, induced an unfolded protein response, and blocked proliferation of cancer cells, including those resistant to bortezomib. Proteomic analysis revealed that capzimin stabilized a subset of polyubiquitinated substrates. Identification of capzimin offers an alternative path to develop proteasome inhibitors for cancer therapy.
Assuntos
Inibidores de Proteassoma/farmacologia , Quinolinas/farmacologia , Transativadores/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/química , Quinolinas/química , Relação Estrutura-Atividade , Transativadores/metabolismoRESUMO
Obesity-associated insulin resistance plays a central role in type 2 diabetes. As such, tyrosine phosphatases that dephosphorylate the insulin receptor (IR) are potential therapeutic targets. The low-molecular-weight protein tyrosine phosphatase (LMPTP) is a proposed IR phosphatase, yet its role in insulin signaling in vivo has not been defined. Here we show that global and liver-specific LMPTP deletion protects mice from high-fat diet-induced diabetes without affecting body weight. To examine the role of the catalytic activity of LMPTP, we developed a small-molecule inhibitor with a novel uncompetitive mechanism, a unique binding site at the opening of the catalytic pocket, and an exquisite selectivity over other phosphatases. This inhibitor is orally bioavailable, and it increases liver IR phosphorylation in vivo and reverses high-fat diet-induced diabetes. Our findings suggest that LMPTP is a key promoter of insulin resistance and that LMPTP inhibitors would be beneficial for treating type 2 diabetes.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Proteínas Tirosina Fosfatases/genética , Bibliotecas de Moléculas Pequenas , Animais , Sítios de Ligação , Diabetes Mellitus Tipo 2/enzimologia , Diabetes Mellitus Tipo 2/genética , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Deleção de Genes , Concentração Inibidora 50 , Camundongos , Camundongos Knockout , Camundongos Obesos , Modelos Biológicos , Estrutura Molecular , Peso Molecular , Bibliotecas de Moléculas Pequenas/farmacologia , Relação Estrutura-AtividadeRESUMO
BACKGROUND: Since malaria parasites highly depend on ribose 5-phosphate for DNA and RNA synthesis and on NADPH as a source of reducing equivalents, the pentose phosphate pathway (PPP) is considered an excellent anti-malarial drug target. In Plasmodium, a bifunctional enzyme named glucose 6-phosphate dehydrogenase 6-phosphogluconolactonase (GluPho) catalyzes the first two steps of the PPP. PfGluPho has been shown to be essential for the growth of blood stage Plasmodium falciparum parasites. METHODS: Plasmodium vivax glucose 6-phosphate dehydrogenase (PvG6PD) was cloned, recombinantly produced in Escherichia coli, purified, and characterized via enzyme kinetics and inhibitor studies. The effects of post-translational cysteine modifications were assessed via western blotting and enzyme activity assays. Genetically encoded probes were employed to study the effects of G6PD inhibitors on the cytosolic redox potential of Plasmodium. RESULTS: Here the recombinant production and characterization of PvG6PD, the C-terminal and NADPH-producing part of PvGluPho, is described. A comparison with PfG6PD (the NADPH-producing part of PfGluPho) indicates that the P. vivax enzyme has higher KM values for the substrate and cofactor. Like the P. falciparum enzyme, PvG6PD is hardly affected by S-glutathionylation and moderately by S-nitrosation. Since there are several naturally occurring variants of PfGluPho, the impact of these mutations on the kinetic properties of the enzyme was analysed. Notably, in contrast to many human G6PD variants, the mutations resulted in only minor changes in enzyme activity. Moreover, nanomolar IC50 values of several compounds were determined on P. vivax G6PD (including ellagic acid, flavellagic acid, and coruleoellagic acid), inhibitors that had been previously characterized on PfGluPho. ML304, a recently developed PfGluPho inhibitor, was verified to also be active on PvG6PD. Using genetically encoded probes, ML304 was confirmed to disturb the cytosolic glutathione-dependent redox potential of P. falciparum blood stage parasites. Finally, a new series of novel small molecules with the potential to inhibit the falciparum and vivax enzymes were synthesized, resulting in two compounds with nanomolar activity. CONCLUSION: The characterization of PvG6PD makes this enzyme accessible to further drug discovery activities. In contrast to naturally occurring G6PD variants in the human host that can alter the kinetic properties of the enzyme and thus the redox homeostasis of the cells, the naturally occurring PfGluPho variants studied here are unlikely to have a major impact on the parasites' redox homeostasis. Several classes of inhibitors have been successfully tested and are presently being followed up.
Assuntos
Hidrolases de Éster Carboxílico/genética , Glucosefosfato Desidrogenase/genética , Malária Vivax/genética , Complexos Multienzimáticos/genética , Proteínas de Protozoários/genética , Hidrolases de Éster Carboxílico/metabolismo , Clonagem Molecular , Citosol/metabolismo , Escherichia coli/metabolismo , Glucosefosfato Desidrogenase/antagonistas & inibidores , Glucosefosfato Desidrogenase/metabolismo , Cinética , Malária Vivax/enzimologia , Malária Vivax/metabolismo , Complexos Multienzimáticos/metabolismo , Oxirredução , Proteínas de Protozoários/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
Hepatic cystogenesis in polycystic liver disease is associated with increased levels of cyclic adenosine monophosphate (cAMP) in cholangiocytes lining liver cysts. Takeda G protein receptor 5 (TGR5), a G protein-coupled bile acid receptor, is linked to cAMP and expressed in cholangiocytes. Therefore, we hypothesized that TGR5 might contribute to disease progression. We examined expression of TGR5 and Gα proteins in cultured cholangiocytes and in livers of animal models and humans with polycystic liver disease. In vitro, we assessed cholangiocyte proliferation, cAMP levels, and cyst growth in response to (1) TGR5 agonists (taurolithocholic acid, oleanolic acid [OA], and two synthetic compounds), (2) a novel TGR5 antagonist (m-tolyl 5-chloro-2-[ethylsulfonyl] pyrimidine-4-carboxylate [SBI-115]), and (3) a combination of SBI-115 and pasireotide, a somatostatin receptor analogue. In vivo, we examined hepatic cystogenesis in OA-treated polycystic kidney rats and after genetic elimination of TGR5 in double mutant TGR5-/- ;Pkhd1del2/del2 mice. Compared to control, expression of TGR5 and Gαs (but not Gαi and Gαq ) proteins was increased 2-fold to 3-fold in cystic cholangiocytes in vitro and in vivo. In vitro, TGR5 stimulation enhanced cAMP production, cell proliferation, and cyst growth by â¼40%; these effects were abolished after TGR5 reduction by short hairpin RNA. OA increased cystogenesis in polycystic kidney rats by 35%; in contrast, hepatic cystic areas were decreased by 45% in TGR5-deficient TGR5-/- ;Pkhd1del2/del2 mice. TGR5 expression and its colocalization with Gαs were increased â¼2-fold upon OA treatment. Levels of cAMP, cell proliferation, and cyst growth in vitro were decreased by â¼30% in cystic cholangiocytes after treatment with SBI-115 alone and by â¼50% when SBI-115 was combined with pasireotide. CONCLUSION: TGR5 contributes to hepatic cystogenesis by increasing cAMP and enhancing cholangiocyte proliferation; our data suggest that a TGR5 antagonist alone or concurrently with somatostatin receptor agonists represents a potential therapeutic approach in polycystic liver disease. (Hepatology 2017;66:1197-1218).
Assuntos
AMP Cíclico/metabolismo , Cistos/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Hepatopatias/metabolismo , Pirimidinas/uso terapêutico , Receptores Acoplados a Proteínas G/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Animais , Proliferação de Células/efeitos dos fármacos , Cistos/tratamento farmacológico , Avaliação Pré-Clínica de Medicamentos , Quimioterapia Combinada , Humanos , Hepatopatias/tratamento farmacológico , Camundongos , Ácido Oleanólico , Doenças Renais Policísticas/metabolismo , Cultura Primária de Células , Pirimidinas/farmacologia , Ratos , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/genética , Somatostatina/análogos & derivados , Somatostatina/farmacologia , Somatostatina/uso terapêuticoRESUMO
Tissue-nonspecific alkaline phosphatase (TNAP) is an ectoenzyme crucial for bone matrix mineralization via its ability to hydrolyze extracellular inorganic pyrophosphate (ePPi), a potent mineralization inhibitor, to phosphate (Pi). By the controlled hydrolysis of ePPi, TNAP maintains the correct ratio of Pi to ePPi and therefore enables normal skeletal and dental calcification. In other areas of the body low ePPi levels lead to the development of pathological soft-tissue calcification, which can progress to a number of disorders. TNAP inhibitors have been shown to prevent these processes via an increase of ePPi. Herein we describe the use of a whole blood assay to optimize a previously described series of TNAP inhibitors resulting in 5-((5-chloro-2-methoxyphenyl)sulfonamido)nicotinamide (SBI-425), a potent, selective and oral bioavailable compound that robustly inhibits TNAP in vivo.
Assuntos
Fosfatase Alcalina/antagonistas & inibidores , Inibidores Enzimáticos/química , Niacinamida/análogos & derivados , Niacinamida/química , Sulfonamidas/química , Administração Oral , Fosfatase Alcalina/metabolismo , Animais , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacocinética , Meia-Vida , Concentração Inibidora 50 , Camundongos , Niacinamida/metabolismo , Niacinamida/farmacocinética , Relação Estrutura-Atividade , Sulfonamidas/metabolismo , Sulfonamidas/farmacocinéticaRESUMO
ARTEMIS is a member of the metallo-ß-lactamase protein family. ARTEMIS has endonuclease activity at DNA hairpins and at 5'- and 3'-DNA overhangs of duplex DNA, and this endonucleolytic activity is dependent upon DNA-PKcs. There has been uncertainty about whether ARTEMIS also has 5'-exonuclease activity on single-stranded DNA and 5'-overhangs, because this 5'-exonuclease is not dependent upon DNA-PKcs. Here, we show that the 5'-exonuclease and the endonuclease activities co-purify. Second, we show that a point mutant of ARTEMIS at a putative active site residue (H115A) markedly reduces both the endonuclease activity and the 5'-exonuclease activity. Third, divalent cation effects on the 5'-exonuclease and the endonuclease parallel one another. Fourth, both the endonuclease activity and 5'-exonuclease activity of ARTEMIS can be blocked in parallel by small molecule inhibitors, which do not block unrelated nucleases. We conclude that the 5'-exonuclease is intrinsic to ARTEMIS, making it relevant to the role of ARTEMIS in nonhomologous DNA end joining.
Assuntos
DNA/química , Desoxirribonuclease I/metabolismo , Exodesoxirribonucleases/metabolismo , Proteínas Nucleares/metabolismo , Nucleotidases/química , Cromatografia , Dicroísmo Circular , Reparo do DNA por Junção de Extremidades , Proteínas de Ligação a DNA , Endonucleases , Células HEK293 , Humanos , Mutagênese , Proteínas Nucleares/genética , Oligonucleotídeos/química , Mutação Puntual , TransfecçãoRESUMO
Increasing the number of ß cells is critical to a definitive therapy for diabetes. Previously, we discovered potent synthetic small molecule antagonists of the nuclear receptor transcription factor HNF4α. The natural ligands of HNF4α are thought to be fatty acids. Because obesity, in which there are high circulating levels of free fatty acids, is one of the few conditions leading to ß-cell hyperplasia, we tested the hypothesis that a potent HNF4α antagonist might stimulate ß-cell replication. A bioavailable HNF4α antagonist was injected into normal mice and rabbits and ß-cell ablated mice and the effect on ß-cell replication was measured. In normal mice and rabbits, the compound induced ß-cell replication and repressed the expression of multiple cyclin-dependent kinase inhibitors, including p16 that plays a critical role in suppressing ß-cell replication. Interestingly, in ß-cell ablated mice, the compound induced α- and δ-cell, in addition to ß-cell replication, and ß-cell number was substantially increased. Overall, the data presented here are consistent with a model in which the well-known effects of obesity and high fat diet on ß-cell replication occur by inhibition of HNF4α. The availability of a potent synthetic HNF4α antagonist raises the possibility that this effect might be a viable route to promote significant increases in ß-cell replication in diseases with reduced ß-cell mass, including type I and type II diabetes.
Assuntos
Fator 4 Nuclear de Hepatócito/antagonistas & inibidores , Células Secretoras de Insulina/metabolismo , Ácido Oleico/farmacologia , Ácidos Palmíticos/farmacologia , Animais , Processos de Crescimento Celular/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Células Hep G2 , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Coelhos , Distribuição AleatóriaRESUMO
A scaffold-hop program seeking full agonists of the neurotensin-1 (NTR1) receptor identified the probe molecule ML301 (1) and associated analogs, including its naphthyl analog (14) which exhibited similar properties. Compound 1 showed full agonist behavior (79-93%) with an EC50 of 2.0-4.1µM against NTR1. Compound 1 also showed good activity in a Ca mobilization FLIPR assay (93% efficacy at 298nM), consistent with it functioning via the Gq coupled pathway, and good selectivity relative to NTR2 and GPR35. In further profiling, 1 showed low potential for promiscuity and good overall pharmacological data. This report describes the discovery, synthesis, and SAR of 1 and associated analogs. Initial in vitro pharmacologic characterization is also presented.