Beta 3-adrenergic receptor-mediated lipolysis and oxygen consumption in brown adipocytes from cynomolgus monkeys.

Primary adipocytes were isolated from axillary brown adipose tissue from adult cynomolgus monkeys. That this tissue contained brown adipocytes was verified by morphological examination and by demonstrating the presence of uncoupling protein messenger ribonucleic acid in the isolated adipocytes. The contributions of beta 1-, beta 2-, and beta 3-adrenergic receptors (AR) to lipolysis and oxygen consumption of isolated brown adipocytes were determined after agonist stimulation. Dose responses were determined using isoproterenol (a nonselective beta-AR agonist), denopamine (beta 1-AR agonist), procaterol (beta 2-AR agonist), and CGP12177A (beta 1- and beta 2-AR antagonist, beta 3-AR agonist). Isoproterenol, denopamine, and procaterol stimulated lipolysis with EC50 values of 4,500, and 83 nmol/L, respectively. Intrinsic activities (relative to isoproterenol maxima) were 100%, 74%, and 59%, respectively. The presence of beta 3-ARs coupled to lipolysis was demonstrated by the activity of CGP12177A (EC50 = 1.6 mumol/L; intrinsic activity = 62%). Isoproterenol stimulated oxygen consumption of brown adipocytes by 75-100% above the basal rate, with an EC50 of 1 mumol/L. Denopamine, procaterol, and CGP12177A stimulated oxygen consumption at a concentration of 100 mumol/L. These results demonstrate that all three beta-adrenergic receptor subtypes are coupled to lipolysis and oxygen consumption in brown adipocytes from cynomolgus monkeys.

Implementing multilevel dynamic scheduling for a highly flexible 5-rail high throughput screening system.

As automation solves the bottleneck involved in drug screening, new bottlenecks present themselves. Some of these bottlenecks include sample management, hit picking and confirmation, and reagents lost as a result of incomplete runs. To keep up with the demands of a large HTS department, scientists spend a disproportionate amount of time simply feeding these systems with samples and reagents. Automating the sample management functions directly on the screening systems would solve this problem. With the use of online data analysis, an integrated sample store permits automated hit picking and confirmation. In addition to these issues, other bottlenecks are often caused by instrument malfunctions. A single lost run can now mean a loss of hundreds of plates and the reagents associated with their testing. A system was designed to include four assaying systems that are fed by an automated online sample repository system. Redundancy between the assaying systems allows for an extra level of error handling in case of a malfunction. The control of such a system requires a sophisticated scheduler/controller software package capable of coordinating the interaction between multiple systems and reacting to changes in the robotic environment in realtime. This paper discusses the design of the system as well as the requirements and selection of an appropriate scheduler/controller package.

A simple automated solution for removing and applying sealing microplate lids.

With the improved reliability and efficiency of automation, there has been an increased desire to integrate automated sample management with automated screening systems. In order to store samples "on line" for an extended period of time, an automation-compatible means for sealing and unsealing microplates is necessary. Numerous commercial solutions are available for removing loose-fitting microplate lids; however, the task of removing a tight-fitting matted lid such as the RoboLid is more challenging. This paper discusses the design of an automated workstation for the application and removal of such tight-fitting microplate lids.

BMS-180560, an insurmountable inhibitor of angiotensin II-stimulated responses: comparison with losartan and EXP3174.

1. This study compares the activity of BMS-180560 (2-butyl-1-chloro-1-[[1-[2-(2H-tetrazol-5-yl)phenyl]-1H-indol-4- yl]methyl]-1H-imidazole-5-carboxylic acid), an insurmountable angiotensin II (AII) receptor antagonist, with that of losartan and EXP3174 in functional and biochemical models of AII-receptor activation. 2. BMS-180560 selectively inhibited [125I]-Sar1Ile8AII ([125I]SI-AII) binding to rat aortic smooth muscle (RASM) cell and rat adrenal cortical AT1 receptors (Ki = 7.6 +/- 1.2 and 18.4 +/- 3.9 nM respectively) compared to adrenal cortical AT2 receptors (Ki = 37.6 +/- 1.3 microM). The Ki values of BMS-180560 and EXP3174, but not losartan, varied as a function of the BSA concentration used in the assays, indicating that the diacid drugs bound to albumin. 3. BMS-180560 (3-300 nM) increased the KD of SI-AII for RASM cell AT1 receptors. Only at high concentrations of BMS-180560 (300 nM) were Bmax values decreased. 4. BMS-180560 inhibited AII-stimulated contraction of rabbit aorta with a calculated KB = 0.068 +/- 0.048 nM and decreased maximal AII-stimulated contraction at 1 nM BMS-180560 by 75%. In the presence of 0.1% BSA, a higher KB value (5.2 +/- 0.92 nM) was obtained. Losartan behaved as a competitive antagonist with a KB = 2.6 +/- 0.13 nM. Contraction stimulated by endothelin-1, noradrenaline, KCl, or the TXA2 receptor agonist U-46619 were unaffected by BMS-180560 (1 nM). 5. AII stimulated the acidification rates of RASM cells as measured by a Cytosensor microphysiometer with an EC50 of 18 nM. Losartan (30 nM) shifted the AII concentration-effect curves in a competitive manner whereas BMS-180560 (0.01 and 0.1 nM) decreased the maximum responses by 60 and 75% respectively. Inhibition by losartan and BMS-180560 could be reversed following washout although recovery took longer for BMS-180560. 6. In [3H]-myoinositol-labelled RASM cells, losartan (30 and 200 nM), shifted the EC50 for AII-stimulated [3H]-inositol monophosphaste formation to higher values, with no change in the maximal response. By contrast, EXP3174 (0.1 to 1 nM) decreased the maximal response in a concentration-dependent manner (17-55%). BMS-180560 (3 and 10 nM) increased the EC50 for AII and decreased the maximum response by 30 and 80% respectively. The inhibition by EXP3174 and BMS-180560 could be reversed by inclusion of losartan (200 nM) indicating that the inhibition was not irreversible. 7. In conclusion, BMS-180560 is a potent, specific, predominantly competitive, reversible All receptor antagonist, which displays insurmountable receptor antagonism. At concentrations of BMS-180560 which have no effect on receptor number, BMS-180560 produced insurmountable antagonism of AII-stimulated second messenger formation, extracellular acidification, and smooth muscle contraction.

Ethanol and diolein stimulate PKC translocation in astroglial cells.

Ethanol exposure stimulates taurine release from astroglial cells. To determine if ethanol mediates this release using protein kinase C (PKC), PKC activity was measured using LRM55 astroglial cells. When ethanol (25-200 mM) or diolein (3 microM) was applied to cells for 30 seconds, PKC activity was observed to decrease in the cytosol and increase in the membrane fraction of the cell while the whole cell activity remained unchanged. The membrane-associated activity increased by almost 100%. When ethanol (100 mM) and diolein (3 microM) were applied simultaneously, membrane-associated activity increased to become 3-5 times greater than when either PKC activator was applied alone. These changes in PKC activity parallel changes in taurine release observed when cells are exposed to ethanol and the PKC activator diolein. Ethanol-stimulated release may be associated with the translocation of PKC activity from the cytosol to the membrane.

Arylpropanolamines: selective beta3 agonists arising from strategies to mitigate phase I metabolic transformations.

Utilization of N-substituted-4-hydroxy-3-methylsulfonanilidoethanolamines 1 as selective beta(3) agonists is complicated by their propensity to undergo metabolic oxidative N-dealkylation, generating 0.01-2% of a very potent alpha(1) adrenergic agonist 2. A summary of the SAR for this hepatic microsomal conversion precedes presentation of strategies to maintain the advantages of chemotype 1 while mitigating the consequences of N-dealkylation. This effort led to the identification of 4-hydroxy-3-methylsulfonanilidopropanolamines 15 for which the SAR for the unique stereochemical requirements for binding to the beta adrenergic receptors culminated in the identification of the potent, selective beta(3) agonist 15f.

Ligand-receptor binding measured by laser-scanning imaging.

This report describes the integration of laser-scanning fluorometric cytometry and nonseparation ligand-binding techniques to provide new assay methods adaptable to miniaturization and high-throughput screening. Receptor-bound, cyanine dye-labeled ligands, [Cy]ligands, were discriminated from those free in solution by measuring the accumulated fluorescence associated with a receptor-containing particle. To illustrate the various binding formats accommodated by this technique, saturation- and competition-binding analyses were performed with [Cy]ligands and their cognate receptors expressed in CHO cells or as fusion proteins coated on polystyrene microspheres. We have successfully applied this technique to the analysis of G protein-coupled receptors, cytokine receptors, and SH2 domains. Multiparameter readouts from ligands labeled separately with Cy5 and Cy5.5 demonstrate the simultaneous analysis of two target receptors in a single well. In addition, laser-scanning cytometry has been used to assay enzymes such as phosphatases and in the development of single-step fluorescent immunoassays.

Mutational analysis of the endothelin type A receptor (ETA): interactions and model of selective ETA antagonist BMS-182874 with putative ETA receptor binding cavity.

Endothelin (ET) receptor antagonism is a potential therapeutic intervention in the treatment of vascular diseases. To elucidate the mechanism of antagonist-ET receptor complex formation, the interactions of four chemically distinct antagonists were investigated using a combination of genetic and biochemical approaches. By site-specific mutagenesis we previously demonstrated that Tyr129 in the second transmembrane domain was critical for high-affinity, subtype-selective binding to the A subtype of ET (ETA) receptors [Krystek et al. (1994) J. Biol. Chem. 269, 12383-12386]. Affinities of the constrained cyclic pentapeptide BQ-123, the pyrimidinylbenzenesulfonamide bosentan, the indancarboxlic acid SB 209670, and the naphthalenesulfonamide BMS-182874 were decreased 20-1000-fold in Tyr129Ala, Tyr129Ser, and Tyr129His ETA receptor mutants. Substitution of Tyr129 with Phe or Trp did not alter the high-affinity binding of BQ-123, bosentan, or SB 209670. BMS-182874 binding affinity was decreased 10-fold in Tyr129Phe and Tyr129trp ET receptors. These data indicate a role of aromatic interactions in the binding of these antagonists to ETA receptors an, in the case of BMS-182874, also suggested a hydrogen bond with the tyrosine hydroxyl. This hypothesis was supported by structure-activity data with analogs of BMS-182874 that varied the C-5 dimethylamino substituent on the naphthalene ring. Mutation of Asp126 and Asp133 also altered binding of BMS-182874 and C-5 analogs. In all cases, naphthalenesulfonamide binding was more severely affected by mutation of Asp133 than by mutation of Asp126. Phosphoinositide hydrolysis and extracellular acidification rate studies demonstrated the importance of Tyr129 to ETA-mediated signal transduction. On the basis of these data, two plausible models of the docked conformation of BMS-182874 in the ETA receptor are proposed as a starting point for further delineation of interactions that underlie antagonist-ETA receptor complex formation.

BMS-201620: a selective beta 3 agonist.

A series of N-(4-hydroxy-3-methylsulfonanilidoethanol)arylglycinamides were prepared and evaluated for their human beta3 adrenergic receptor agonist activity. SAR studies led to the identification of BMS-201620 (39), a potent beta3 full agonist (Ki = 93 nM, 93% activation). Based on its favorable safety profile, BMS-201620 was chosen for clinical evaluation.

Beta 3 agonists. Part 1: evolution from inception to BMS-194449.

Screening of the BMS collection identified 4-hydroxy-3-methylsulfonanilidoethanolamines as full beta 3 agonists. Substitution of the ethanolamine nitrogen with a benzyl group bearing a para hydrogen bond acceptor promoted beta(3) selectivity. SAR elucidation established that highly selective beta(3) agonists were generated upon substitution of C(alpha) with either benzyl to form (R)-1,2-diarylethylamines or with aryl to generate 1,1-diarylmethylamines. This latter subset yielded a clinical candidate, BMS-194449 (35).(1)

BMS-196085: a potent and selective full agonist of the human beta(3) adrenergic receptor.

A series of 4-hydroxy-3-methylsulfonanilido-1,2-diarylethylamines were prepared and evaluated for their human beta(3) adrenergic receptor agonist activity. SAR studies led to the identification of BMS-196085 (25), a potent beta(3) full agonist (K(i)=21 nM, 95% activation) with partial agonist (45%) activity at the beta(1) receptor. Based on its desirable in vitro and in vivo properties, BMS-196085 was chosen for clinical evaluation.