RESUMEN
Atrial fibrillation (AF) is the most common cardiac arrhythmia, and a significant risk factor for ischemic stroke and heart failure. Marketed anti-arrhythmic drugs can restore sinus rhythm, but with limited efficacy and significant toxicities, including potential to induce ventricular arrhythmia. Atrial-selective ion channel drugs are expected to restore and maintain sinus rhythm without risk of ventricular arrhythmia. One such atrial-selective channel target is GIRK1/4 (G-protein regulated inwardly rectifying potassium channel 1/4). Here we describe 14b, a potent GIRK1/4 inhibitor developed to cardiovert AF to sinus rhythm while minimizing central nervous system exposure - an issue with preceding GIRK1/4 clinical candidates.
Asunto(s)
Fibrilación Atrial , Humanos , Fibrilación Atrial/tratamiento farmacológico , Cardioversión Eléctrica , Atrios Cardíacos , EncéfaloRESUMEN
This Letter describes methodology to enable the identification of tool or therapeutic lipopeptides which modulate the function of membrane bound proteins. The choice of lipopeptides as a chemotype is the amalgamation of multiple medicinal chemistry considerations including duration of action, low systemic exposure and access to intracellular components. The 'lipopeptide shuffle' has been applied here to the APJ receptor and has rapidly resulted in the discovery of a 33 nM APJ agonist hit from an initial 369 member lipopeptide synthetic array.
Asunto(s)
Diseño de Fármacos , Lipopéptidos/farmacología , Receptores Acoplados a Proteínas G/agonistas , Receptores de Apelina , Relación Dosis-Respuesta a Droga , Humanos , Lipopéptidos/química , Lipopéptidos/genética , Conformación Molecular , Relación Estructura-ActividadRESUMEN
The mouse is a useful preclinical species for evaluating disease etiology due to the availability of a wide variety of genetically modified strains and the ability to perform disease-modifying manipulations. In order to establish an atrial filtration (AF) model in our laboratory, we profiled several commonly used murine AF models. We initially evaluated a pharmacological model of acute carbachol (CCh) treatment plus atrial burst pacing in C57BL/6 mice. In an effort to observe micro-reentrant circuits indicative of authentic AF, we employed optical mapping imaging in isolated mouse hearts. While CCh reduced atrial refractoriness and increased atrial tachyarrhythmia vulnerability, the left atrial (LA) excitation patterns were rather regular without reentrant circuits or wavelets. Therefore, the atrial tachyarrhythmia resembled high frequency atrial flutter, not typical AF per se. We next examined both a chronic angiotensin II (Ang II) infusion model and the surgical model of transverse aortic constriction (TAC), which have both been reported to induce atrial and ventricular structural changes that serve as a substrates for micro-reentrant AF. Although we observed some extent of atrial remodeling such as fibrosis or enlarged LA diameter, burst pacing-induced atrial tachyarrhythmia vulnerability did not differ from control mice in either model. This again suggested that an AF-like pathophysiology is difficult to demonstrate in the mouse. To continue searching for a valid murine AF model, we studied mice with a cardiac-specific deficiency (KO) in liver kinase B1 (Cardiac-LKB1), which has been reported to exhibit spontaneous AF. Indeed, the electrocardiograms (ECG) of conscious Cardiac-LKB1 KO mice exhibited no P waves and had irregular RR intervals, which are characteristics of AF. Histological evaluation of Cardiac-LKB1 KO mice revealed dilated and fibrotic atria, again consistent with AF. However, atrial electrograms and optical mapping revealed that electrical activity was limited to the sino-atrial node area with no electrical conduction into the atrial myocardium beyond. Thus, Cardiac-LKB1 KO mice have severe atrial myopathy or atrial standstill, but not AF. In summary, the atrial tachyarrhythmias we observed in the four murine models were distinct from typical human AF, which often exhibits micro- or macro-reentrant atrial circuits. Our results suggest that the four murine AF models we examined may not reflect human AF well, and raise a cautionary note for use of those murine models to study AF.
Asunto(s)
Fibrilación Atrial/fisiopatología , Modelos Animales de Enfermedad , Proteínas Quinasas Activadas por AMP/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Animales , Aleteo Atrial/fisiopatología , Función del Atrio Izquierdo/fisiología , Remodelación Atrial , Carbacol/farmacología , Estimulación Cardíaca Artificial/efectos adversos , Electrocardiografía , Ratones , Ratones Endogámicos C57BL , Miocardio/patología , Miocitos Cardíacos/patología , Taquicardia Ventricular/fisiopatologíaRESUMEN
The use of stable isotopically labeled substrates and analysis by mass spectrometry have provided substantial insight into rates of synthesis, disposition, and utilization of lipids in vivo. The information to be gained from such studies is of particular benefit to therapeutic research where the underlying causes of disease may be related to the production and utilization of lipids. When studying biology through the use of isotope tracers, care must be exercised in interpreting the data to ensure that any response observed can truly be interpreted as biological and not as an artifact of the experimental design or a dilutional effect on the isotope. We studied the effects of dosing route and tracer concentration on the mass isotopomer distribution profile as well as the action of selective inhibitors of microsomal tri-glyceride transfer protein (MTP) in mice and diacylglycerol acyltransferase 1 (DGAT1) in nonhuman primates, using a stable-isotopically labeled approach. Subjects were treated with inhibitor and subsequently given a dose of uniformly ¹³C-labeled oleic acid. Samples were analyzed using a rapid LC-MS technique, allowing the effects of the intervention on the assembly and disposition of triglycerides, cholesteryl esters, and phospholipids to be determined in a single 3 min run from just 10 µl of plasma.
Asunto(s)
Proteínas Portadoras/metabolismo , Ésteres del Colesterol/sangre , Diacilglicerol O-Acetiltransferasa/metabolismo , Metabolismo de los Lípidos , Lipoproteínas/sangre , Ácido Oléico , Triglicéridos/sangre , Animales , Proteínas Portadoras/antagonistas & inhibidores , Chlorocebus aethiops , Cromatografía Liquida , Vías de Administración de Medicamentos , Evaluación Preclínica de Medicamentos/métodos , Inhibidores Enzimáticos/farmacología , Femenino , Marcaje Isotópico/métodos , Isótopos/análisis , Isótopos/sangre , Masculino , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Ácido Oléico/metabolismo , Ácido Oléico/farmacologíaRESUMEN
Saccharomyces cerevisiae has proven to be a useful model organism for the study of telomerase, a specialized cellular reverse transcriptase that helps maintain genomic stability by adding telomeric DNA repeats to the ends of chromosomes. Yeast telomerase is thought to be a holoenzyme containing Est2p and TLC1 RNA, the catalytic subunit and its intrinsic template, respectively, as well as the TLC1-RNA-associated factors Est1p and Est3p. Cdc13p, a sequence-specific telomere-DNA-binding protein, is also required for action in vivo. A current model for telomerase regulation is that telomere-associated Cdc13p binds Est1p, thereby recruiting telomerase. However, recent chromatin immunoprecipitation experiments suggest an alternate role for Est1p in activating Est2p-TLC1-RNA that is already bound to the telomere. Three models for Est1p activation are presented.
Asunto(s)
Proteínas Fúngicas , Proteínas de Saccharomyces cerevisiae , Telomerasa/metabolismo , Telómero/enzimología , Ciclina B/genética , Ciclina B/metabolismo , Proteínas de Unión al ADN , Proteínas/genética , Proteínas/metabolismo , Telomerasa/genética , Telómero/genéticaRESUMEN
OBJECTIVE: To examine the effects of treatments with niacin or anacetrapib (an inhibitor of cholesteryl ester transfer protein) on the ability of high-density lipoprotein (HDL) to promote net cholesterol efflux and reduce toll-like receptor-mediated inflammation in macrophages. METHODS AND RESULTS: A total of 18 patients received niacin, 2 g/d, for 4 weeks; 20 patients received anacetrapib, 300 mg/d, for 8 weeks; and 2 groups (n=4 and n=5 patients) received placebo. HDL samples were isolated by polyethylene glycol precipitation or ultracentrifugation, tested for the ability to promote cholesterol efflux in cholesterol-loaded THP-I or mouse peritoneal macrophages, or used to pretreat macrophages, followed by lipopolysaccharide exposure. HDL cholesterol levels were increased by 30% in response to niacin and by approximately 100% in response to anacetrapib. Niacin treatment increased HDL-mediated net cholesterol efflux from foam cells, primarily by increasing HDL concentration, whereas anacetrapib treatment increased cholesterol efflux by both increasing HDL concentration and causing increased efflux at matched HDL concentrations. The increased efflux potential of anacetrapib-HDL was more prominent at higher HDL cholesterol concentrations (>12 microg/mL), which was associated with an increased content of lecithin-cholesterol acyltransferase (LCAT) and apolipoprotein E and completely dependent on the expression of ATP binding cassette transporters (ABCA1 and ABCG1). Potent antiinflammatory effects of HDL were observed at low HDL concentrations (3 to 20 microg/mL) and were partly dependent on the expression of ABCA1 and ABCG1. All HDL preparations showed similar antiinflammatory effects, proportionate to the HDL cholesterol concentration. CONCLUSIONS: Niacin treatment caused a moderate increase in the ability of HDL to promote net cholesterol efflux, whereas inhibition of cholesteryl ester transfer protein via anacetrapib led to a more dramatic increase in association with enhanced particle functionality at higher HDL concentrations. All HDLs exhibited potent ability to suppress macrophage toll-like receptor 4-mediated inflammatory responses, in a process partly dependent on cholesterol efflux via ABCA1 and ABCG1.
Asunto(s)
Antiinflamatorios/uso terapéutico , Proteínas de Transferencia de Ésteres de Colesterol/antagonistas & inhibidores , HDL-Colesterol/sangre , Colesterol/sangre , Dislipidemias/tratamiento farmacológico , Hipolipemiantes/uso terapéutico , Inflamación/prevención & control , Macrófagos/metabolismo , Niacina/uso terapéutico , Oxazolidinonas/uso terapéutico , Transportador 1 de Casete de Unión a ATP , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 1 , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Animales , Antiinflamatorios/efectos adversos , Células Cultivadas , Proteínas de Transferencia de Ésteres de Colesterol/metabolismo , Ensayos Clínicos como Asunto , Dislipidemias/sangre , Dislipidemias/inmunología , Células Espumosas/metabolismo , Humanos , Hipolipemiantes/efectos adversos , Inflamación/inmunología , Inflamación/metabolismo , Mediadores de Inflamación/metabolismo , Lipoproteínas/deficiencia , Lipoproteínas/genética , Lipoproteínas/metabolismo , Macrófagos/inmunología , Ratones , Ratones Noqueados , Niacina/efectos adversos , Oxazolidinonas/efectos adversos , Factores de Tiempo , Receptor Toll-Like 4/metabolismo , Resultado del TratamientoRESUMEN
Amino-anthranilic acid derivatives have been identified as a new class of low serum shifted, high affinity full agonists of the human orphan G-protein-coupled receptor GPR109a with improved ADME properties.
Asunto(s)
Descubrimiento de Drogas , Receptores Acoplados a Proteínas G/agonistas , Animales , Flúor/química , Humanos , Concentración 50 Inhibidora , Ratones , Estructura Molecular , Niacina/síntesis química , Niacina/química , Niacina/farmacología , Piridinas/síntesis química , Piridinas/química , Ratas , Ratas Sprague-Dawley , Receptores NicotínicosRESUMEN
Tricyclic pyrazole tetrazoles which are potent partial agonists of the high affinity niacin receptor, GPR109a, have been discovered and optimized. One of these compounds has proven to be effective at lowering free fatty acids in vitro and in vivo.
Asunto(s)
Pirazoles/química , Receptores Acoplados a Proteínas G/agonistas , Tetrazoles/química , Vasodilatadores/química , Animales , Perros , Haplorrinos , Humanos , Ratones , Ratas , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismo , Tetrazoles/síntesis química , Tetrazoles/farmacocinética , Vasodilatadores/síntesis química , Vasodilatadores/farmacocinéticaRESUMEN
A series of pyrazolyl propionyl cyclohexenamides were discovered as full agonists for the high affinity niacin receptor GPR109A. The structure-activity relationship (SAR) studies were aimed to improve activity on GPR109A, reduce Cytochrome P450 2C8 (CYP2C8) and Cytochrome P450 2C9 (CYP2C9) inhibition, reduce serum shift and improve pharmacokinetic (PK) profiles.
Asunto(s)
Amidas/química , Ciclohexenos/farmacología , Receptores Acoplados a Proteínas G/agonistas , Animales , Ciclohexenos/química , Ciclohexenos/farmacocinética , Ratones , Ratas , Receptores Nicotínicos , Relación Estructura-ActividadRESUMEN
Niacin is an effective drug for raising HDL cholesterol. However, niacin must be taken in large doses and significant side effects are often observed, including facial flushing, loss of glucose tolerance, and liver toxicity. An anthranilic acid was identified as an agonist of the niacin receptor. In order to improve efficacy and provide structural diversity, replacements for the anthranilic acid were investigated and several compounds with improved properties were identified.
Asunto(s)
Niacina/metabolismo , Receptores de Droga/metabolismo , ortoaminobenzoatos/química , Disponibilidad BiológicaRESUMEN
5-Alkyl and aryl-pyrazole-acids have been identified as a new class of selective, small-molecule, agonists of the human orphan G-protein-coupled receptor GPR109a, a high affinity receptor for the HDL-raising drug nicotinic acid.
Asunto(s)
Pirazoles/química , Receptores Acoplados a Proteínas G/agonistas , Animales , Ácidos Grasos/metabolismo , Humanos , Ratones , Niacina/química , Pirazoles/síntesis química , Pirazoles/farmacocinética , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismoRESUMEN
Niacin is an effective drug for raising HDL cholesterol and reducing coronary risks, but patients show low compliance with treatment due to severe facial flushing upon taking the drug. A series of bicyclic pyrazole carboxylic acids were synthesized and tested for their ability to activate the niacin receptor. One analog, 23, showed improved potency and lacked flushing at doses that effectively altered the lipid profile of rats.
Asunto(s)
Dislipidemias/tratamiento farmacológico , Hipolipemiantes/farmacología , Niacina/farmacología , Agonistas Nicotínicos/farmacología , Pirazoles/farmacología , Animales , HDL-Colesterol/metabolismo , Ácidos Grasos no Esterificados/metabolismo , Hipolipemiantes/síntesis química , Hipolipemiantes/química , Ratones , Niacina/química , Agonistas Nicotínicos/síntesis química , Agonistas Nicotínicos/química , Pirazoles/síntesis química , Pirazoles/química , Ratas , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/metabolismoRESUMEN
5-Alkyl and aryl-pyrazole-tetrazoles have been identified as a new class of selective, small-molecule, agonists of the human G-protein-coupled receptor GPR109a, a high affinity receptor for the HDL-raising drug nicotinic acid.
Asunto(s)
Pirazoles/química , Receptores Acoplados a Proteínas G/agonistas , Tetrazoles/química , Animales , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Agonistas Nicotínicos/química , Agonistas Nicotínicos/farmacología , Pirazoles/farmacología , Receptores Acoplados a Proteínas G/deficiencia , Receptores Acoplados a Proteínas G/fisiología , Receptores Nicotínicos/deficiencia , Receptores Nicotínicos/fisiología , Tetrazoles/farmacología , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiologíaRESUMEN
The heterodimeric Ku complex affects telomere structure in diverse organisms. We report here that in the absence of Ku, the catalytic subunit of telomerase, Est2p, was not telomere-associated in G1 phase, and its association in late S phase was decreased. The telomere association of Est1p, a telomerase component that binds telomeres only in late S phase, was also reduced in the absence of Ku. The effects of Ku on telomerase binding require a 48-nucleotide (nt) stem-loop region of TLC1 telomerase RNA. Ku interacts with TLC1 RNA via this 48-nt region throughout the cell cycle, but this interaction was reduced after telomere replication. These data support a model in which Ku recruits telomerase to telomeres in G1 phase when telomerase is inactive and promotes telomerase-mediated telomere lengthening in late S phase.
Asunto(s)
Antígenos Nucleares/metabolismo , Ciclo Celular , Proteínas de Unión al ADN/metabolismo , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/metabolismo , Telomerasa/metabolismo , Antígenos Nucleares/genética , Proteínas de Unión al ADN/genética , Autoantígeno Ku , Conformación de Ácido Nucleico , Unión Proteica , ARN/química , ARN/metabolismo , ARN de Hongos/química , ARN de Hongos/metabolismo , Fase S , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Telomerasa/química , Telomerasa/genética , Telómero/metabolismo , Proteínas de Unión a Telómeros/metabolismoRESUMEN
Heavy exercise or oxygen deficit often links with higher levels of arterial lactate and lower levels of plasma free fatty acids (FFA). Treatment with lactate reduces circulating levels of FFA in vivo and lipolysis in adipose tissues in vitro. However, the underlying mechanism has remained unclear. Here we employ pharmacological and genetic approaches to show that GPR81, an orphan G-protein-coupled receptor with relatively restricted expression in the adipose tissues, functions as a receptor for lactate and can mediate an anti-lipolytic effect of lactate. GPR81 may thus function as a sensor of lactate that can modulate the FFA pool under exercise or conditions of oxygen deficit.
Asunto(s)
Tejido Adiposo/metabolismo , Ácidos Grasos no Esterificados/metabolismo , Ácido Láctico/metabolismo , Lipólisis , Receptores Acoplados a Proteínas G/fisiología , Tejido Adiposo/efectos de los fármacos , Animales , Células CHO , Cricetinae , Cricetulus , Humanos , Ácido Láctico/farmacología , Ligandos , Lipólisis/efectos de los fármacos , Lipólisis/genética , Ratones , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/genética , Receptores Nicotínicos/genética , Receptores Nicotínicos/fisiología , TransfecciónRESUMEN
Pyrazolopyrimidines were discovered as the first class of allosteric agonists for the high affinity nicotinic acid receptor GPR109A. In addition to its intrinsic activity, compound 9n significantly enhances nicotinic acid binding to the receptor, thereby potentiating the functional efficacy of nicotinic acid.
Asunto(s)
Agonistas Nicotínicos/síntesis química , Agonistas Nicotínicos/farmacología , Pirazoles/síntesis química , Pirazoles/farmacología , Pirimidinas/síntesis química , Pirimidinas/farmacología , Receptores Acoplados a Proteínas G/agonistas , Sitios de Unión , Técnicas Químicas Combinatorias , Humanos , Estructura Molecular , Niacina/metabolismo , Agonistas Nicotínicos/química , Pirazoles/química , Pirimidinas/química , Receptores Nicotínicos , Relación Estructura-ActividadRESUMEN
A homology model of the nicotinic acid receptor GPR109A was constructed based on the X-ray crystal structure of bovine rhodopsin. An HTS hit was docked into the homology model. Characterization of the binding pocket by a grid-based surface calculation of the docking model suggested that a larger hydrophobic body plus a polar tail would improve interaction between the ligand and the receptor. The designed compounds were synthesized, and showed significantly improved binding affinity and activation of GPR109A.
Asunto(s)
Modelos Moleculares , Agonistas Nicotínicos/síntesis química , Agonistas Nicotínicos/farmacología , Receptores Acoplados a Proteínas G/agonistas , ortoaminobenzoatos/síntesis química , ortoaminobenzoatos/farmacología , Sitios de Unión , Técnicas Químicas Combinatorias , Humanos , Estructura Molecular , Niacina/metabolismo , Agonistas Nicotínicos/química , Receptores Nicotínicos , Relación Estructura-Actividad , ortoaminobenzoatos/químicaRESUMEN
The design, synthesis, and biological activity of a series of cycloalkene acid-based niacin receptor agonists are described. This led to the discovery that tetrahydro anthranilic acid is an excellent surrogate for anthranilic acid. Several compounds were identified that were potent against the niacin receptor, had enhanced cytochrome P450 selectivity against subtypes CYP2C8 and CYP2C9, and improved oral exposure in mice.
Asunto(s)
Ciclohexenos/síntesis química , Ciclohexenos/farmacología , Ciclopentanos/síntesis química , Ciclopentanos/farmacología , Sistema Enzimático del Citocromo P-450/metabolismo , Agonistas Nicotínicos/síntesis química , Agonistas Nicotínicos/farmacología , ortoaminobenzoatos/síntesis química , ortoaminobenzoatos/farmacología , Animales , Hidrocarburo de Aril Hidroxilasas/efectos de los fármacos , Ciclohexenos/química , Ciclohexenos/farmacocinética , Ciclopentanos/química , Ciclopentanos/farmacocinética , Citocromo P-450 CYP2C8 , Citocromo P-450 CYP2C9 , Diseño de Fármacos , Humanos , Ratones , Agonistas Nicotínicos/química , Antagonistas Nicotínicos/farmacología , ortoaminobenzoatos/química , ortoaminobenzoatos/farmacocinéticaRESUMEN
Biaryl anthranilides are reported as potent and selective full agonists for the high affinity niacin receptor GPR109A. The SAR presented outlines approaches to reduce serum shift and both CYPCYP2C8 and CYP2C9 liabilities, while improving PK and maintaining excellent receptor activity. Compound 2i exhibited good in vivo antilipolytic efficacy while providing a significantly improved therapeutic index over vasodilation (flushing) with respect to niacin in the mouse model.
Asunto(s)
Receptores Acoplados a Proteínas G/agonistas , ortoaminobenzoatos/síntesis química , Amidas/síntesis química , Amidas/farmacocinética , Amidas/farmacología , Animales , Hidrocarburo de Aril Hidroxilasas/antagonistas & inhibidores , Unión Competitiva , Células CHO , Cricetinae , Cricetulus , Citocromo P-450 CYP2C8 , Citocromo P-450 CYP2C9 , Humanos , Técnicas In Vitro , Ratones , Microsomas Hepáticos/metabolismo , Ensayo de Unión Radioligante , Receptores Nicotínicos , Relación Estructura-Actividad , ortoaminobenzoatos/farmacocinética , ortoaminobenzoatos/farmacologíaRESUMEN
INTRODUCTION: GPR109A is the receptor mediating both the antilipolytic and vasodilatory effects of nicotinic acid. In order to develop agonists for GPR109A with improved therapeutic indices we have sought to optimize animal models that evaluate both nicotinic acid-mediated inhibition of lipolysis and stimulation of vasodilatation. The rat and the dog have previously been used to study the antilipolytic effects of nicotinic acid, but no optimal vasodilatation model exits in either species. METHODS: We have developed a vasodilatation model in the rat that measures changes in ear perfusion using laser Doppler flowmetry. In the dog, we have developed a model of vasodilatation measuring changes in red color values in the ear, using a spectrocolorimeter. Effects of GPR109A agonists on lipolysis were measured in both species after oral dosing of compounds, and measuring plasma levels of free fatty acids. RESULTS: In both rat and dog, GPR109A agonists induce dose- and time-dependent vasodilatation, similar to that observed in humans. Vasodilatation is inhibited in both species with cyclooxygenase inhibitors or a specific DP1 receptor antagonist, indicating that, as in man, nicotinic acid-induced vasodilatation in rats and dogs is mainly mediated by the release of PGD(2). DISCUSSION: Our results show that both rat and dog are useful models for the characterization of GPR109A agonists. A therapeutic index for GPR109A agonists can be calculated in either species.