Identification and synthesis of [1,2,4]triazolo[3,4-a]phthalazine derivatives as high-affinity ligands to the alpha 2 delta-1 subunit of voltage gated calcium channel

We have identified and synthesized a series of [1,2,4]triazolo[3,4-a]phthalazine derivatives as high-affinity ligands to alpha 2 delta-1 subunit of voltage gated calcium channels. Structure-activity relationship studies directed toward improving the potency and physical properties of 2 lead to the discovery of 20 (IC(50)=15 nM) and (S)-22 (IC(50)=30 nM). A potent and selective radioligand, [(3)H]-(S)-22 was also synthesized to demonstrate that this ligand binds to the same site as gabapentin.     

Expedited SAR study of an mGluR5 antagonists: generation of a focused library using a solution-phase Suzuki coupling methodology

The SAR of the lead compounds 2a and 2b was rapidly explored. Utilizing a parallel solution-phase Suzuki coupling approach, in tandem with strong cation exchange resin (SCX) purification afforded the desired focused library. The library was evaluated in vitro, a ninefold potency increase was achieved and the preference for ortho substitution of moderate steric bulk of the fourth, phenyl ring was identified. In addition, dimethylisoxazole, as a heterocyclic replacement for the phenylic ring of the lead compound, was also identified by this approach.     

Flow cytometric assessment of the signaling status of human B lymphocytes from normal and autoimmune individuals

Abnormalities in lymphocyte signaling cascades are thought to play an important role in the development of autoimmune disease. However, the large amount of cellular material needed for standard biochemical assessment of signaling status has made it difficult to evaluate putative abnormalities completely using primary lymphocytes. The development of technology to employ intracellular staining and flow cytometry to assess the signaling status of individual cells has now made it possible to delineate the perturbations that are present in lymphocytes from patients with autoimmune disease. As an example, human B cells from the Ramos B cell line and the periphery of systemic lupus erythematosus (SLE) patients or normal nonautoimmune controls were assessed for activation of the NF-kappaB and mitogen activated protein kinase (MAPK) signaling cascades by intracellular multiparameter flow cytometric analysis and biochemical Western blotting. In combination with fluorochrome conjugated antibodies specific for surface proteins that define B cell subsets, antibodies that recognize activated, or phosphorylated inhibitors of kappaB (IkappaB) as well as the extracellular regulated kinase (ERK), jun N-terminal kinase (JNK) or p38 MAPKs were used to stain fixed and permeabilized human B cells and analyze them flow cytometrically. Examination of the known signaling pathways following engagement of CD40 on human B cells confirmed that intracellular flow cytometry and Western blotting equivalently assay CD154-induced phosphorylation and degradation of IkappaB proteins as well as phosphorylation of the MAPKs ERK, JNK and p38. In addition, B cells from the periphery of SLE patients had a more activated status immediately ex vivo as assessed by intracellular flow cytometric analysis of phosphorylated ERK, JNK and p38 when compared with B cells from the periphery of normal, nonautoimmune individuals. Together, these results indicate that multiparameter intracellular flow cytometric analysis of signaling pathways, such as the NF-kappaB and MAPK cascades, can be used routinely to assess the activation status of a small number of cells and thus delineate abnormalities in signaling molecules expressed in primary lymphocytes from patients with autoimmune disease.     

Ext1-dependent heparan sulfate regulates the range of Ihh signaling during endochondral ossification

Exostosin1 (Ext1) belongs to a family of glycosyltransferases necessary for the synthesis of the heparan sulfate (HS) chains of proteoglycans, which regulate signaling of several growth factors. Loss of tout velu (ttv), the homolog of Ext1 in Drosophila, inhibits Hedgehog movement. In contrast, we show that reduced HS synthesis in mice carrying a hypomorphic mutation in Ext1 results in an elevated range of Indian hedgehog (Ihh) signaling during embryonic chondrocyte differentiation. Our data suggest a dual function for HS: First, HS is necessary to bind Hedgehog in the extracellular space. Second, HS negatively regulates the range of Hedgehog signaling in a concentration-dependent manner. Additionally, our data indicate that Ihh acts as a long-range morphogen, directly activating the expression of parathyroid hormone-like hormone. Finally, we propose that the development of exostoses in the human Hereditary Multiple Exostoses syndrome can be attributed to activation of Ihh signaling.     

Synthesis and evaluation of phenylcarbamate derivatives as ligands for nicotinic acetylcholine receptors

Phenylcarbamate derivatives were synthesized and evaluated in radioligand binding assays for different nicotinic acetylcholine receptor (nAChR) subtypes. Carbamate derivatives bearing a pyrrolidine or piperidine moiety 8-20 exhibited much lower affinity for alpha7* nAChR than the analogues in the quinuclidine series 21-25, although the same structural elements are present. Furthermore, in contrast to the quinuclidine analogues 21-25, all (S)-pyrrolidine derivatives 8-12 and the piperidine analogues 15 and 16 exhibited higher affinities for alpha4beta2* nAChR.     

Muscular myosin isoforms of Taenia solium (Cestoda)

Type II myosin, the primary component of the thick filament of muscle fibers, is organized as a dimeric high molecular weight protein, and is composed of a pair of heavy chains (MHC) and two pairs of light chains. Myosin II transforms ATP energy into mechanical force. All type II myosins are conserved proteins but they have two variable regions that are located in different places of the molecule. Myosin molecules are encoded by a multigene family and many isoforms are generated. The expression of myosins depends on the developmental stage and on the type and degree of contractile activity and tissue, therefore several myosin isoforms are found in the same organism. Here we describe the use of different techniques that allowed demonstrating the presence of isoforms of the heavy chain type II myosin of Taenia solium cysticerci (larvae) and tapeworms (adults), a cestode parasite of importance in public health in many developing countries. Myosin was purified and used in comparative proteolytic fragmentation, ATPase activity, detection of antigenic differences and electrophoretic separation. The results obtained showed biochemical and immunochemical differences among cysticerci and tapeworms, and demonstrate the presence of myosin isoforms in T. solium that are probably associated to physiological requirements of each developmental stage.     

Activation of group IV cytosolic phospholipase A2 in human eosinophils by phosphoinositide 3-kinase through a mitogen-activated protein kinase-independent pathway

Activation of group IV cytosolic phospholipase A(2) (gIV-PLA(2)) is the essential first step in the synthesis of inflammatory eicosanoids and in integrin-mediated adhesion of leukocytes. Prior investigations have demonstrated that phosphorylation of gIV-PLA(2) results from activation of at least two isoforms of mitogen-activated protein kinase (MAPK). We investigated the potential role of phosphoinositide 3-kinase (PI3K) in the activation of gIV-PLA(2) and the hydrolysis of membrane phosphatidylcholine in fMLP-stimulated human blood eosinophils. Transduction into eosinophils of Deltap85, a dominant negative form of class IA PI3K adaptor subunit, fused to an HIV-TAT protein transduction domain (TAT-Deltap85) concentration dependently inhibited fMLP-stimulated phosphorylation of protein kinase B, a downstream target of PI3K. FMLP caused increased arachidonic acid (AA) release and secretion of leukotriene C(4) (LTC(4)). TAT-Deltap85 and LY294002, a PI3K inhibitor, blocked the phosphorylation of gIV-PLA(2) at Ser(505) caused by fMLP, thus inhibiting gIV-PLA(2) hydrolysis and production of AA and LTC(4) in eosinophils. FMLP also caused extracellular signal-related kinases 1 and 2 and p38 MAPK phosphorylation in eosinophils; however, neither phosphorylation of extracellular signal-related kinases 1 and 2 nor p38 was inhibited by TAT-Deltap85 or LY294002. Inhibition of 1) p70 S6 kinase by rapamycin, 2) protein kinase B by Akt inhibitor, or 3) protein kinase C by Ro-31-8220, the potential downstream targets of PI3K for activation of gIV-PLA(2), had no effect on AA release or LTC(4) secretion caused by fMLP. We find that PI3K is required for gIV-PLA(2) activation and hydrolytic production of AA in activated eosinophils. Our data suggest that this essential PI3K independently activates gIV-PLA(2) through a pathway that does not involve MAPK.     

Macrophage-tropic simian/human immunodeficiency virus chimeras use CXCR4, not CCR5, for infections of rhesus macaque peripheral blood mononuclear cells and alveolar macrophages

After the nearly complete and irreversible depletion of CD4(+) T lymphocytes induced by highly pathogenic simian/human immunodeficiency virus chimeric viruses (SHIVs) during infections of rhesus monkeys, tissue macrophages are able to sustain high levels (>10(6) viral RNA copies/ml) of plasma viremia for several months. We recently reported that the virus present in the plasma during the late macrophage phase of infection had acquired changes that specifically targeted the V2 region of gp120 (H. Imamichi et al., Proc. Natl. Acad. Sci. USA 99:13813-13818, 2002); some of these SHIV variants were macrophage-tropic (M-tropic). Those findings have been extended by examining the tropic properties, coreceptor usage, and gp120 structure of five independent SHIVs recovered directly from lymph nodes of late-stage animals. All of these tissue-derived SHIV isolates were able to infect alveolar macrophages. These M-tropic SHIVs used CXCR4, not CCR5, for infections of rhesus monkey PBMC and primary alveolar macrophages. Because the starting highly pathogenic T-tropic SHIV inoculum also utilized CXCR4, these results indicate that the acquisition of M-tropism in the SHIV-macaque system is not accompanied by a change in coreceptor usage. Compared to the initial T-tropic SHIV inoculum, tissue-derived M-tropic SHIVs from individual infected animals carry gp120s containing similar changes (specific amino acid deletions, substitutions, and loss of N-linked glycosylation sites), primarily within the V1 and/or V2 regions of gp120.