The EV71 vaccine provided protection against EV71-associated hand, foot, and mouth disease or herpangina in infants and young children. (Funded by Sinovac Biotech; ClinicalTrials.gov number, NCT01507857.).

Dual orthosteric agonists of metabotropic glutamate 2 (mGlu2) and mGlu3 receptors are being developed as novel antipsychotic agents devoid of the adverse effects of conventional antipsychotics. Therefore, these drugs could be helpful for the treatment of psychotic symptoms associated with Alzheimer's disease (AD). In experimental animals, the antipsychotic activity of mGlu2/3 receptor agonists is largely mediated by the activation of mGlu2 receptors and is mimicked by selective positive allosteric modulators (PAMs) of mGlu2 receptors. We investigated the distinct influence of mGlu2 and mGlu3 receptors in mixed and pure neuronal cultures exposed to synthetic ␤-amyloid protein (A␤) to model neurodegeneration occurring in AD. The mGlu2 receptor PAM, N-4Ј-cyano-biphenyl-3-yl)-N-(3-pyridinylmethyl)-ethanesulfonamide hydrochloride (LY566332), devoid of toxicity per se, amplified A␤-induced neurodegeneration, and this effect was prevented by the mGlu2/3 receptor antagonist (2S,1ЈS,2ЈS)-2-(9-xanthylmethyl)-2-(2Ј-carboxycyclopropyl)glycine (LY341495). LY566332 potentiated A␤ toxicity regardless of the presence of glial mGlu3 receptors, but it was inactive when neurons lacked mGlu2 receptors. The dual mGlu2/3 receptor agonist, (Ϫ)-2-oxa-4-aminobicyclo[3.1.0]exhane-4,6-dicarboxylic acid (LY379268), was neuroprotective in mixed cultures via a paracrine mechanism mediated by transforming growth factor-␤1. LY379268 lost its protective activity in neurons grown with astrocytes lacking mGlu3 receptors, indicating that protection against A␤ neurotoxicity was mediated entirely by glial mGlu3 receptors. The selective noncompetitive mGlu3 receptor antagonist, (3S)-1-(5-bromopyrimidin-2-yl)-N- (2,4-dichlorobenzyl)pyrrolidin-3-amine methanesulfonate hydrate (LY2389575), amplified A␤ toxicity on its own, and, interestingly, unmasked a neurotoxic activity of LY379268, which probably was mediated by the activation of mGlu2 receptors. These data indicate that selective potentiation of mGlu2 receptors enhances neuronal vulnerability to A␤, whereas dual activation of mGlu2 and mGlu3 receptors is protective against A␤-induced toxicity.

Mixed lineage kinase 7 (MLK7) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that activates the pro-apoptotic signaling pathways p38 and JNK. A library of potential kinase inhibitors was screened, and a series of dihydropyrrolopyrazole quinolines was identified as highly potent inhibitors of MLK7 in vitro catalytic activity. Of this series, an aryl-substituted dihydropyrrolopyrazole quinoline (DHP-2) demonstrated an IC 50 of 70 nM for inhibition of pJNK formation in COS-7 cell MLK7/JNK co-transfection assays. In stimulated cells, DHP-2 at 200 nM or MLK7 small interfering RNA completely blocked anisomycin and UV induced but had no effect on interleukin-1␤ or tumor necrosis factor-␣-induced p38 and JNK activation. Additionally, the compound blocked anisomycin and UV-induced apoptosis in COS-7 cells. Heart tissue homogenates from MLK7 transgenic mice treated with DHP-2 at 30 mg/kg had reduced JNK and p38 activation with no apparent effect on ERK activation, demonstrating that this compound can be used to block MLK7-driven MAPK pathway activation in vivo. Taken together, these data demonstrate that MLK7 is the MAPKKK required for modulation of the stressactivated MAPKs downstream of anisomycin and UV stimulation and that DHP-2 can be used to block MLK7 pathway activation in cells as well as in vivo.The mitogen-activated protein kinases (MAPK) 1 are a highly conserved family of signal transduction molecules that transmits extracellular signals from the membrane to the nucleus. There are three major branches of MAPK signaling that include ERK, c-Jun N-terminal kinase (JNK) and p38. The JNK and p38 branches of the MAPK family are activated by stress stimuli including cytokines, osmotic stress, mitogens, UV irradiation, chemotherapeutic agents, and anisomycin (1, 2). There are three kinases that form a MAPK signaling module where a MAPK is activated by a MAPK kinase (MAPKK), which in turn is regulated by a MAPKK kinase (MAPKKK) (Fig. 1). The upstream activation of JNK and p38 is complex, allowing for activation of this pathway in multiple cells and by multiple stimuli. Cellular and receptor specificity of the pathway is conferred by protein-protein interactions where the MAPK and a MAPKK assemble with a specific MAPKKK on scaffold proteins such as JNK-interacting protein (3, 4) or ␤-arrestin (5). The resulting signaling module acts as a bridge joining the appropriate receptor to the downstream effectors, enabling activation of the stress-activated MAPK.The most distal point at which signal and cell specificity for JNK and p38 activation is conferred is at the MAPKKK level. Mixed lineage kinases (MLKs) are a family of MAPKKKs activating JNK and p38. There are currently seven mammalian kinases belonging to the MLK family that have recently been reviewed (6, 7). These kinases can be divided into three subclasses based on sequence similarity and domain structure, and they include MLK1-4, dual leucine zipper kinases, and the zipper sterile ␣-motif kinases (ZAKs). Although much is known about the mechanisms re...

The binding site for DETQ [2-(2,6-dichlorophenyl)-1-((1,3)-3-(hydroxymethyl)-5-(2-hydroxypropan-2-yl)-1-methyl-3,4-dihydroisoquinolin-2(1)-yl)ethan-1-one], a positive allosteric modulator (PAM) of the dopamine D1 receptor, was identified and compared with the binding site for CID 2886111 [-(6--butyl-3-carbamoyl-4,5,6,7-tetrahydro-1-benzothiophen-2-yl)pyridine-4-carboxamide], a reference D1 PAM. From D1/D5 chimeras, the site responsible for potentiation by DETQ of the increase in cAMP in response to dopamine was narrowed down to the N-terminal intracellular quadrant of the receptor; arginine-130 in intracellular loop 2 (IC2) was then identified as a critical amino acid based on a human/rat species difference. Confirming the importance of IC2, a 2-adrenergic receptor construct in which the IC2 region was replaced with its D1 counterpart gained the ability to respond to DETQ. A homology model was built from the agonist-state2-receptor structure, and DETQ was found to dock to a cleft created by IC2 and adjacent portions of transmembrane helices 3 and 4 (TM3 and TM4). When residues modeled as pointing into the cleft were mutated to alanine, large reductions in the potency of DETQ were found for Val119 and Trp123 (flanking the conserved DRY sequence in TM3), Arg130 (located in IC2), and Leu143 (TM4). The D1/D5 difference was found to reside in Ala139; changing this residue to methionine as in the D5 receptor reduced the potency of DETQ by approximately 1000-fold. None of these mutations affected the activity of CID 2886111, indicating that it binds to a different allosteric site. When combined, DETQ and CID 2886111 elicited a supra-additive response in the absence of dopamine, implying that both PAMs can bind to the D1 receptor simultaneously.

As part of our ongoing research to identify novel agents acting at metabotropic glutamate 2 (mGlu2) and 3 (mGlu3) receptors, we have previously reported the identification of the C4α-methyl analog of mGlu2/3 receptor agonist 1 (LY354740). This molecule, 1S,2S,4R,5R,6S-2-amino-4-methylbicyclo[3.1.0]hexane-2,6-dicarboxylate 2 (LY541850), exhibited an unexpected mGlu2 agonist/mGlu3 antagonist pharmacological profile, whereas the C4β-methyl diastereomer (3) possessed dual mGlu2/3 receptor agonist activity. We have now further explored this structure-activity relationship through the preparation of cyclic and acyclic C4-disubstituted analogs of 1, leading to the identification of C4-spirocyclopropane 5 (LY2934747), a novel, potent, and systemically bioavailable mGlu2/3 receptor agonist which exhibits both antipsychotic and analgesic properties in vivo. In addition, through the combined use of protein-ligand X-ray crystallography employing recombinant human mGlu2/3 receptor amino terminal domains, molecular modeling, and site-directed mutagenesis, a molecular basis for the observed pharmacological profile of compound 2 is proposed.

Allosteric potentiators amplify the sensitivity of physiologic control circuits, a mode of action that could provide therapeutic advantages. This hypothesis was tested with the dopamine D1 receptor potentiator DETQ [2-(2,6-dichlorophenyl)-1-((1S,3R)-3-(hydroxymethyl)-5-(2-hydroxypropan-2-yl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl)ethan-1-one]. In human embryonic kidney 293 (HEK293) cells expressing the human D1 receptor, DETQ induced a 21-fold leftward shift in the cAMP response to dopamine, with a Kb of 26 nM. The maximum response to DETQ alone was ∼12% of the maximum response to dopamine, suggesting weak allosteric agonist activity. DETQ was ∼30-fold less potent at rat and mouse D1 receptors and was inactive at the human D5 receptor. To enable studies in rodents, an hD1 knock-in mouse was generated. DETQ (3–20 mg/kg orally) caused a robust (∼10-fold) increase in locomotor activity (LMA) in habituated hD1 mice but was inactive in wild-type mice. The LMA response to DETQ was blocked by the D1 antagonist SCH39166 and was dependent on endogenous dopamine. LMA reached a plateau at higher doses (30–240 mg/kg) even though free brain levels of DETQ continued to increase over the entire dose range. In contrast, the D1 agonists SKF 82958, A-77636, and dihydrexidine showed bell-shaped dose-response curves with a profound reduction in LMA at higher doses; video-tracking confirmed that the reduction in LMA caused by SKF 82958 was due to competing stereotyped behaviors. When dosed daily for 4 days, DETQ continued to elicit an increase in LMA, whereas the D1 agonist A-77636 showed complete tachyphylaxis by day 2. These results confirm that allosteric potentiators may have advantages compared with direct-acting agonists.

The normalization of excessive glutamatergic neurotransmission through the activation of metabotropic glutamate 2 (mGlu2) receptors may have therapeutic potential in a variety of psychiatric disorders, including anxiety/depression and schizophrenia. Here, we characterize the pharmacological properties of N- (4-((2-(trifluoromethyl)-3-hydroxy-4-(isobutyryl)phenoxy)methyl)benzyl)-1-methyl-1H-imidazole-4-carboxamide (THIIC), a structurally novel, potent, and selective allosteric potentiator of human and rat mGlu2 receptors (EC 50 ϭ 23 and 13 nM, respectively). THIIC produced anxiolytic-like efficacy in the rat stress-induced hyperthermia assay and the mouse stress-induced elevation of cerebellar cGMP and marble-burying assays. THIIC also produced robust activity in three assays that detect antidepressant-like activity, including the mouse forced-swim test, the rat differential reinforcement of low rate 72-s assay, and the rat dominant-submissive test, with a maximal response similar to that of imipramine. Effects of THIIC in the forced-swim test and marble burying were deleted in mGlu2 receptor null mice. Analysis of sleep electroencephalogram (EEG) showed that THIIC had a sleeppromoting profile with increased non-rapid eye movement (REM) and decreased REM sleep. THIIC also decreased the dark phase increase in extracellular histamine in the medial prefrontal cortex and decreased levels of the histamine metabolite tele-methylhistamine (t-MeHA) in rat cerebrospinal fluid. Collectively, these results indicate that the novel mGlu2-positive allosteric modulator THIIC has robust activity in models used to predict anxiolytic/antidepressant efficacy, substantiating, at least with this molecule, differentiation in the biological impact of mGlu2 potentiation versus mGlu2/3 orthosteric agonism. In addition, we provide evidence that sleep EEG and CSF t-MeHA might function as viable biomarker approaches to facilitate the translational development of THIIC and other mGlu2 potentiators.

BackgroundThe major etiology of hand, foot and mouth disease (HFMD) is infection with human enterovirus A (HEV-A). Among subtypes of HEV-A, coxsackievirusA16 (CoxA16) and enterovirus 71 (EV71) are major causes for recurrent HFMD among infants and children in Jiangsu Province, mainland China. Here, we analyzed maternal antibodies between prenatal women and their neonates, to determine age-specific seroprevalence of human EV71 and CoxA16 infections in infants and children aged 0 to 15 years. The results may facilitate the development of immunization against HFMD.MethodsThis study used cross-section of 40 pairs of pregnant women and neonates and 800 subjects aged 1 month to 15 years old. Micro-dose cytopathogenic effects measured neutralizing antibodies against EV71 and CoxA16. Chi-square test compared seroprevalence rates between age groups and McNemar test, paired-Samples t-test and independent-samples t-test analyzed differences of geometric mean titers.ResultsA strong correlation between titers of neutralizing antibody against EV71 and CoxA16 in prenatal women and neonates was observed (rEV71 = 0.67, rCoxA16 = 0.56, respectively, p < 0.05). Seroprevalence rates of anti-EV71 antibody gradually decreased with age between 0 to 6 months old, remained low between 7 to 11 months (5.0–10.0%), and increased between 1 and 4 years (22.5–87.5%). Age-specific seroprevalence rates of anti-EV71 antibody stabilized in >80% of children between 5 to 15 years of age. However, seroprevalence rates of anti-CoxA16 antibody were very low (0.0–13.0%) between 0 to 6 months of age, gradually increased between 7 months to 4 years (15.0–70.0%), and stabilized at 54.0% (108/200) between 5 to 15 years. Seroprevalence rates against EV71 and CoxA16 were low under 1 year (0.0–10.0%), and showed an age dependent increase with high seroprevalence (52.5–62.5%) between 4 and10 years of age.ConclusionsConcomitant infection of EV71 and CoxA16 was common in Jiangsu Province. Therefore, development of bivalent vaccine against both EV71 and CoxA16 is critical. The optimal schedule for vaccination may be 4 to11 months of age.