Biomedical subjects

Ralph Mosley

Publications and source records attributed to Ralph Mosley.

7 recordsLinked to original sources

PubMed2006

Identification of Leu276 of the S1P1 receptor and Phe263 of the S1P3 receptor in interaction with receptor specific agonists by molecular modeling, site-directed mutagenesis, and affinity studies.

Sphingosine-1-phosphate (S1P) receptor agonists are novel immunosuppressive agents. The selectivity of S1P1 against S1P3 is strongly correlated with lymphocyte sequestration and minimum acute toxicity and bradycardia. This study describes molecular modeling, site-directed mutagenesis, and affinity studies exploring the molecular basis for selectivity between S1P1 and S1P3 receptors. Computational models of human S1P1 and S1P3 receptors bound with two nonselective agonists or two S1P1-selective agonists were developed based on the X-ray crystal structure of bovine rhodopsin. The models predict that S1P1 Leu276 and S1P3 Phe263 contribute to the S1P1/S1P3 selectivity of the two S1P1-selective agonists. These residues were subjected to site-directed mutagenesis. The wild-type and mutant S1P receptors were expressed in Chinese hamster ovary cells and examined for their abilities to bind to and be activated by agonists in vitro. The results indicate that the mutations have minimal effects on the activities of the two nonselective agonists, although they have dramatic effects on the S1P1-selective agonists. These studies provide a fundamental understanding of how these two receptor-selective agonists bind to the S1P1 and S1P3 receptors, which should aid development of more selective S1P1 receptor agonists with immunosuppressive properties and improved safety profiles.

Amino Acid Sequence↗

PubMed2006

6H-Benzo[c]chromen-6-one derivatives as selective ERbeta agonists.

A series of 6H-benzo[c]chromen-6-one and 6H-benzo[c]chromene derivatives were prepared, and the affinity and selectivity for ERalpha and ERbeta was measured. Many of the analogs were found to be potent and selective ERbeta agonists. Bis hydroxyl at positions 3 and 8 is essential for activity in a HTRF coactivator recruitment assay. Additional modifications at both phenyl rings led to compounds with ERbeta<10nM potency and >100-fold selectivity over ERalpha.

Benzene Derivatives↗

PubMed2005

Selective PPARgamma modulators with improved pharmacological profiles.

A series of metabolically robust N-benzyl-indole selective PPARgamma modulators with either a 3-benzoyl or 3-benzisoxazoyl moiety have been identified. In vitro, these compounds are partial agonists and exhibit reduced adipogenesis in human adipocytes. In vivo, these SPPARgammaMs result in potent glucose lowering in db/db mice and attenuate increases in heart weight and brown adipose tissue that is typically observed in rats upon treatment with PPARgamma full agonists.

Animals↗

PubMed2005

Modeling aided design of potent glycogen phosphorylase inhibitors.

Molecular modeling has been used to assist in the development of a novel series of potent glycogen phosphorylase inhibitors based on a phenyl diacid lead, compound 1. In the absence of suitable competitive binding assays, compound 1 was predicted to bind at the AMP allosteric site based on superposition onto known inhibitors which bind at different sites in the enzyme and analyses of the surrounding protein environment associated with these distinct sites. Possible docking modes of compound 1 at the AMP allosteric site were further explored using the crystal structure of rabbit muscle glycogen phosphorylase complexed with a Bayer diacid compound W1807 (PDB entry 3AMV). Compound 1 was predicted to interact with positively charged arginines at the AMP allosteric site in the docking model. Characterization of the binding pocket by a grid-based surface calculation of the docking model revealed a large unfilled hydrophobic region near the central phenyl ring, suggesting that compounds with larger hydrophobic groups in this region would improve binding. A series of naphthyl diacid compounds were designed and synthesized to access this hydrophobic cleft, and showed significantly improved potency.

Adenosine Monophosphate↗

PubMed2005

Web enabling technology for the design, enumeration, optimization and tracking of compound libraries.

Motivated by the need to augment Merck's in-house small molecule collection, web-based tools for designing, enumerating, optimizing and tracking compound libraries have been developed. The path leading to the current version of this Virtual Library Tool Kit (VLTK) is discussed in context of the (then) available commercial offerings and the constraints and requirements imposed by the end users. Though the effort was initiated to simplify the tasks of designing novel, drug-like and diverse compound libraries containing between 2K-10K unique entities, it has also evolved into a powerful tool for outsourcing syntheses as well as lead identification and optimization. The web tool includes components that select reagents, analyze synthons, identify backup reagents, enumerate libraries, calculate properties, optimize libraries and finally track the synthesized compounds through biological assays. In addition to accommodating project specific designs and virtual 3D library scanning, the application includes tools for parallel synthesis, laboratory automation and compound registration.

Combinatorial Chemistry Techniques↗

PubMed2003

Phenylacetic acid derivatives as hPPAR agonists.

Beginning with the weakly active lead structure 1, a new series of hPPAR agonists was developed. In vivo glucose and triglyceride lowering activity was obtained by homologation and oxamination to 3, then conversion to substituted benzisoxazoles 4 and 5. Further manipulation afforded benzofurans 6 and 7. Compound 7 was of comparable potency as a glucose and triglyceride lowering agent in insulin resistant rodents to BRL 49653.

Animals↗

PubMed2003

Distinct properties and advantages of a novel peroxisome proliferator-activated protein [gamma] selective modulator.

Antidiabetic thiazolidinediones (TZDs) and non-TZD compounds have been shown to serve as agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma). Here, we report the identification and characterization of a novel non-TZD selective PPARgamma modulator (nTZDpa). nTZDpa bound potently to PPARgamma with high selectivity vs. PPARalpha or PPARdelta. In cell-based assays for transcriptional activation, nTZDpa served as a selective, potent PPARgamma partial agonist and was able to antagonize the activity of PPARgamma full agonists. nTZDpa also displayed partial agonist effects when its ability to promote adipogenesis in 3T3-L1 cells was evaluated. Assessment of protein conformation using protease protection or solution nuclear magnetic resonance spectroscopy methods showed that nTZDpa produced altered PPARgamma conformational stability vs. full agonists, thereby establishing a physical basis for its observed partial agonism. DNA microarray analysis of RNA from 3T3-L1 adipocytes treated with nTZDpa or several structurally diverse PPARgamma full agonists demonstrated qualitative differences in the affected gene expression profile for nTZDpa. Chronic treatment of fat-fed, C57BL/6J mice with nTZDpa or a TZD full agonist ameliorated hyperglycemia and hyperinsulinemia. However, unlike the TZD, nTZDpa caused reductions in weight gain and adipose depot size. Feed efficiency was also substantially diminished. Unlike TZDs, nTZDpa did not cause cardiac hypertrophy in mice. When a panel of PPARgamma target genes was examined in white adipose tissue, nTZDpa produced a different in vivo expression pattern vs. the full agonist. These findings establish that novel selective PPARgamma modulators can produce altered receptor conformational stability leading to distinctive gene expression profiles, reduced adipogenic cellular effects, and potentially improved in vivo biological responses. Such compounds may lead to preferred therapies for diabetes, obesity, or metabolic syndrome.

Adipocytes↗