ERK5 kinase activity is dispensable for cellular immune response and proliferation.

Unlike other members of the MAPK family, ERK5 contains a large C-terminal domain with transcriptional activation capability in addition to an N-terminal canonical kinase domain. Genetic deletion of ERK5 is embryonic lethal, and tissue-restricted deletions have profound effects on erythroid development, cardiac function, and neurogenesis. In addition, depletion of ERK5 is antiinflammatory and antitumorigenic. Small molecule inhibition of ERK5 has been shown to have promising activity in cell and animal models of inflammation and oncology. Here we report the synthesis and biological characterization of potent, selective ERK5 inhibitors. In contrast to both genetic depletion/deletion of ERK5 and inhibition with previously reported compounds, inhibition of the kinase with the most selective of the new inhibitors had no antiinflammatory or antiproliferative activity. The source of efficacy in previously reported ERK5 inhibitors is shown to be off-target activity on bromodomains, conserved protein modules involved in recognition of acetyl-lysine residues during transcriptional processes. It is likely that phenotypes reported from genetic deletion or depletion of ERK5 arise from removal of a noncatalytic function of ERK5. The newly reported inhibitors should be useful in determining which of the many reported phenotypes are due to kinase activity and delineate which can be pharmacologically targeted.

Structure-activity relationship and improved hydrolytic stability of pyrazole derivatives that are allosteric inhibitors of West Nile Virus NS2B-NS3 proteinase.

West Nile Virus (WNV) is a potentially deadly mosquito-borne flavivirus which has spread rapidly throughout the world. Currently there is no effective vaccine against flaviviral infections. We previously reported the identification of pyrazole ester derivatives as allosteric inhibitors of WNV NS2B-NS3 proteinase. These compounds degrade rapidly in pH 8 buffer with a half life of 1-2h. We now report the design, synthesis and in vitro evaluation of pyrazole derivatives that are inhibitors of WNV NS2B-NS3 proteinase with greatly improved stability in the assay medium.

Design and synthesis of pyrazole derivatives as potent and selective inhibitors of tissue-nonspecific alkaline phosphatase (TNAP).

Tissue-nonspecific alkaline phosphatase (TNAP) plays a central role in regulating extracellular matrix calcification during bone formation and growth. High-throughput screening (HTS) for small molecule TNAP inhibitors led to the identification of hits in the sub-micromolar potency range. We report the design, synthesis and in vitro evaluation of a series of pyrazole derivatives of a screening hit which are potent TNAP inhibitors exhibiting IC(50) values as low as 5nM. A representative of the series was characterized in kinetic studies and determined to have a mode of inhibition not previously observed for TNAP inhibitors.

Total synthesis of (+/-) -phenserine via [4+1] cyclization of a bis(alkylthio)carbene and an indole isocyanate.

[structure: see text]. A total synthesis of acetylcholine blocking agent, phenserine, has been achieved by employing a [4+1] cyclization between an appropriately substituted indole isocyanate and a bis(alkylthio)carbene.

New entry into beta-lactams via reaction of dimethoxycarbene with isocyanates.

[reaction: see text] Highly substituted beta-lactams have been isolated as the major product of the reaction of dimethoxycarbene with selected isocyanates. This reaction offers the potential for rapid access into a variety of highly functionalized species.

Orally active metabotropic glutamate subtype 2 receptor positive allosteric modulators: structure-activity relationships and assessment in a rat model of nicotine dependence.

Compounds that modulate metabotropic glutamate subtype 2 (mGlu(2)) receptors have the potential to treat several disorders of the central nervous system (CNS) including drug dependence. Herein we describe the synthesis and structure-activity relationship (SAR) studies around a series of mGlu(2) receptor positive allosteric modulators (PAMs). The effects of N-substitution (R(1)) and substitutions on the aryl ring (R(2)) were identified as key areas for SAR exploration (Figure 3). Investigation of the effects of varying substituents in both the isoindolinone (2) and benzisothiazolone (3) series led to compounds with improved in vitro potency and/or efficacy. In addition, several analogues exhibited promising pharmacokinetic (PK) properties. Furthermore, compound 2 was shown to dose-dependently decrease nicotine self-administration in rats following oral administration. Our data, showing for the first time efficacy of an mGlu(2) receptor PAM in this in vivo model, suggest potential utility for the treatment of nicotine dependence in humans.

Inhibition of hematopoietic protein tyrosine phosphatase augments and prolongs ERK1/2 and p38 activation.

The hematopoietic protein tyrosine phosphatase (HePTP) is implicated in the development of blood cancers through its ability to negatively regulate the mitogen-activated protein kinases (MAPKs) ERK1/2 and p38. Small-molecule modulators of HePTP activity may become valuable in treating hematopoietic malignancies such as T cell acute lymphoblastic leukemia (T-ALL) and acute myelogenous leukemia (AML). Moreover, such compounds will further elucidate the regulation of MAPKs in hematopoietic cells. Although transient activation of MAPKs is crucial for growth and proliferation, prolonged activation of these important signaling molecules induces differentiation, cell cycle arrest, cell senescence, and apoptosis. Specific HePTP inhibitors may promote the latter and thereby may halt the growth of cancer cells. Here, we report the development of a small molecule that augments ERK1/2 and p38 activation in human T cells, specifically by inhibiting HePTP. Structure-activity relationship analysis, in silico docking studies, and mutagenesis experiments reveal how the inhibitor achieves selectivity for HePTP over related phosphatases by interacting with unique amino acid residues in the periphery of the highly conserved catalytic pocket. Importantly, we utilize this compound to show that pharmacological inhibition of HePTP not only augments but also prolongs activation of ERK1/2 and, especially, p38. Moreover, we present similar effects in leukocytes from mice intraperitoneally injected with the inhibitor at doses as low as 3 mg/kg. Our results warrant future studies with this probe compound that may establish HePTP as a new drug target for acute leukemic conditions.

Design and synthesis of an orally active metabotropic glutamate receptor subtype-2 (mGluR2) positive allosteric modulator (PAM) that decreases cocaine self-administration in rats.

The modification of 3'-((2-cyclopentyl-6,7-dimethyl-1-oxo-2,3-dihydro-1H-inden-5-yloxy)methyl)biphenyl-4-carboxylic acid (BINA, 1) by incorporating heteroatoms into the structure and replacing the cyclopentyl moiety led to the development of new mGluR2 positive allosteric modulators (PAMs) with optimized potency and superior druglike properties. These analogues are more potent than 1 in vitro and are highly selective for mGluR2 vs other mGluR subtypes. They have significantly improved pharmacokinetic (PK) properties, with excellent oral bioavailability and brain penetration. The benzisothiazol-3-one derivative 14 decreased cocaine self-administration in rats, providing proof-of-concept for the use of mGluR2 PAMs for the treatment of cocaine dependence.