Synthesis and evaluation of novel tricyclic benzo[4.5]cyclohepta[1.2]pyridine derivatives as NMDA/NR2B antagonists

A novel series of annulated tricyclic compounds was synthesized and evaluated as NMDA/NR2B antagonists. Structure–activity development was directed towards in vitro optimization of NR2B activity and selectivity over the hERG K⁺ channel. Preferred compounds were subsequently evaluated for selectivity in an α₁-adrenergic receptor binding counter-screen and a cell-based assay of NR2B activity.     

Comparative metagenomics revealed commonly enriched gene sets in human gut microbiomes.

Numerous microbes inhabit the human intestine, many of which are uncharacterized or uncultivable. They form a complex microbial community that deeply affects human physiology. To identify the genomic features common to all human gut microbiomes as well as those variable among them, we performed a large-scale comparative metagenomic analysis of fecal samples from 13 healthy individuals of various ages, including unweaned infants. We found that, while the gut microbiota from unweaned infants were simple and showed a high inter-individual variation in taxonomic and gene composition, those from adults and weaned children were more complex but showed a high functional uniformity regardless of age or sex. In searching for the genes over-represented in gut microbiomes, we identified 237 gene families commonly enriched in adult-type and 136 families in infant-type microbiomes, with a small overlap. An analysis of their predicted functions revealed various strategies employed by each type of microbiota to adapt to its intestinal environment, suggesting that these gene sets encode the core functions of adult and infant-type gut microbiota. By analysing the orphan genes, 647 new gene families were identified to be exclusively present in human intestinal microbiomes. In addition, we discovered a conjugative transposon family explosively amplified in human gut microbiomes, which strongly suggests that the intestine is a 'hot spot' for horizontal gene transfer between microbes.     

Neural expression of G protein-coupled receptors GPR3, GPR6, and GPR12 up-regulates cyclic AMP levels and promotes neurite outgrowth

Cyclic AMP regulates multiple neuronal functions, including neurite outgrowth and axonal regeneration. GPR3, GPR6, and GPR12 make up a family of constitutively active G protein-coupled receptors (GPCRs) that share greater than 50% identity and 65% similarity at the amino acid level. They are highly expressed in the central nervous system, and their expression in various cell lines results in constitutive stimulation of cAMP production. When the constitutively active GPCRs were overexpressed in rat cerebellar granule neurons in culture, the transfected neurons exhibited significantly enhanced neurite outgrowth and overcame growth inhibition caused by myelin-associated glycoprotein. GPR12-mediated neurite outgrowth was the most prominent and was shown to depend on G(s) and cAMP-dependent protein kinase. Moreover, the GPR12-mediated rescue from myelin-associated glycoprotein inhibition was attributable to cAMP-dependent protein kinase-mediated inhibition of the small GTPase, RhoA. Among the three receptors, GPR3 was revealed to be enriched in the developing rat cerebellar granule neurons. When the endogenous GPR3 was knocked down, significant reduction of neurite growth was observed, which was reversed by expression of either GPR3 or GPR12. Taken together, our results indicate that expression of the constitutively active GPCRs up-regulates cAMP production in neurons, stimulates neurite outgrowth, and counteracts myelin inhibition. Further characterization of the GPCRs in developing and injured mammalian neurons should provide insights into how basal cAMP levels are regulated in neurons and could establish a firm scientific foundation for applying receptor biology to treatment of various neurological disorders.     

Genetic characterization of <Emphasis Type="Italic">psp</Emphasis> encoding the DING protein in <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> SBW25

Background  

DING proteins constitute a conserved and broadly distributed set of proteins found in bacteria, fungi, plants and animals (including humans). Characterization of DING proteins from animal and plant tissues indicated ligand-binding ability suggesting a role for DING proteins in cell signaling and biomineralization. Surprisingly, the genes encoding DING proteins in eukaryotes have not been identified in the eukaryotic genome or EST databases. Recent discovery of a DING homologue (named Psp here) in the genome of Pseudomonas fluorescens SBW25 provided a unique opportunity to investigate the physiological roles of DING proteins. P. fluorescens SBW25 is a model bacterium that can efficiently colonize plant surfaces and enhance plant health. In this report we genetically characterize Psp with a focus on conditions under which psp is expressed and the protein exported.     

Delta9-tetrahydrocannabinol selectively acts on CB1 receptors in specific regions of dorsal vagal complex to inhibit emesis in ferrets

The aim of this study was to investigate the efficacy, receptor specificity, and site of action of Delta9-tetrahydrocannabinol (THC) as an antiemetic in the ferret. THC (0.05-1 mg/kg ip) dose-dependently inhibited the emetic actions of cisplatin. The ED50 for retching was approximately 0.1 mg/kg and for vomiting was 0.05 mg/kg. A specific cannabinoid (CB)1 receptor antagonist SR-141716A (5 mg/kg ip) reversed the effect of THC, whereas the CB2 receptor antagonist SR-144528 (5 mg/kg ip) was ineffective. THC applied to the surface of the brain stem was sufficient to inhibit emesis induced by intragastric hypertonic saline. The site of action of THC in the brain stem was further assessed using Fos immunohistochemistry. Fos expression induced by cisplatin in the dorsal motor nucleus of the vagus (DMNX) and the medial subnucleus of the nucleus of the solitary tract (NTS), but not other subnuclei of the NTS, was significantly reduced by THC rostral to obex. At the level of the obex, THC reduced Fos expression in the area postrema and the dorsal subnucleus of the NTS. The highest density of CB1 receptor immunoreactivity was found in the DMNX and the medial subnucleus of the NTS. Lower densities were observed in the area postrema and dorsal subnucleus of the NTS. Caudal to obex, there was moderate density of staining in the commissural subnucleus of the NTS. These results show that THC selectively acts at CB1 receptors to reduce neuronal activation in response to emetic stimuli in specific regions of the dorsal vagal complex.     

Increased expression of bradykinin type-1 receptors in endothelium of intramyocardial coronary vessels in human failing hearts

In experimental animals, bradykinin type-1 receptors (BK-1Rs) are induced during inflammation and ischemia, and, by exerting either cardioprotective or cardiotoxic effects, they may contribute to the pathogenesis of heart failure. Nothing is known about the expression of BK-1Rs in human heart failure. Human heart tissue was obtained from excised hearts of patients undergoing cardiac transplantation (n = 13), due to idiopathic dilated cardiomyopathy (IDC; n = 7) or to coronary heart disease (CHD; n = 6), and from normal hearts (n = 6). The expression of BK-1Rs was analyzed by means of competitive RT-PCR, Western blot analysis, and immunohistochemistry. Expression of BK-1R mRNA was increased in both IDC (2.8-fold) and CHD (2.1-fold) hearts compared with normal hearts. The observed changes were verified at the protein level. Expression of BK-1Rs in failing hearts localized to the endothelium of intramyocardial coronary vessels and correlated with an increased expression of TNF-alpha in the vessel wall. Treatment of human coronary artery endothelial cells with TNF-alpha increases their BK-1R expression. These novel results show that BK-1Rs are induced in the endothelium of intramyocardial coronary vessels in failing human hearts and so may participate in the pathogenesis of heart failure.     

Wound healing and blastema formation in regenerating digit tips of adult mice

Amputation of the distal region of the terminal phalanx of mice causes an initial wound healing response followed by blastema formation and the regeneration of the digit tip. Thus far, most regeneration studies have focused in embryonic or neonatal models and few studies have examined adult digit regeneration. Here we report on studies that include morphological, immunohistological, and volumetric analyses of adult digit regeneration stages. The regenerated digit is grossly similar to the original, but is not a perfect replacement. Re-differentiation of the digit tip occurs by intramembranous ossification forming a trabecular bone network that replaces the amputated cortical bone. The digit blastema is comprised of proliferating cells that express vimentin, a general mesenchymal marker, and by comparison to mature tissues, contains fewer endothelial cells indicative of reduced vascularity. The majority of blastemal cells expressing the stem cell marker SCA-1, also co-express the endothelial marker CD31, suggesting the presence of endothelial progenitor cells. Epidermal closure during wound healing is very slow and is characterized by a failure of the wound epidermis to close across amputated bone. Instead, the wound healing phase is associated with an osteoclast response that degrades the stump bone allowing the wound epidermis to undercut the distal bone resulting in a novel re-amputation response. Thus, the regeneration process initiates from a level that is proximal to the original plane of amputation.     

Inhibition of In Vivo HIV Infection in Humanized Mice by Gene Therapy of Human Hematopoietic Stem Cells with a Lentiviral Vector Encoding a Broadly Neutralizing Anti-HIV Antibody

Due to the inherent immune evasion properties of the HIV envelope, broadly neutralizing HIV-specific antibodies capable of suppressing HIV infection are rarely produced by infected individuals. We examined the feasibility of utilizing genetic engineering to circumvent the restricted capacity of individuals to endogenously produce broadly neutralizing HIV-specific antibodies. We constructed a single lentiviral vector that encoded the heavy and light chains of 2G12, a broadly neutralizing anti-HIV human antibody, and that efficiently transduced and directed primary human B cells to secrete 2G12. To evaluate the capacity of this approach to provide protection from in vivo HIV infection, we used the humanized NOD/SCID/γ_c^null mouse model, which becomes populated with human B cells, T cells, and macrophages after transplantation with human hematopoietic stem cells (hu-HSC) and develops in vivo infection after inoculation with HIV. The plasma of the irradiated NOD/SCID/γ_c^null mice transplanted with hu-HSC transduced with the 2G12-encoding lentivirus contained 2G12 antibody, likely secreted by progeny human lymphoid and/or myeloid cells. After intraperitoneal inoculation with high-titer HIV-1_JR-CSF, mice engrafted with 2G12-transduced hu-HSC displayed marked inhibition of in vivo HIV infection as manifested by a profound 70-fold reduction in plasma HIV RNA levels and an almost 200-fold reduction in HIV-infected human cell numbers in mouse spleens, compared to control hu-HSC-transplanted NOD/SCID/γ_c^null mice inoculated with equivalent high-titer HIV-1_JR-CSF. These results support the potential efficacy of this new gene therapy approach of using lentiviral vectors encoding a mixture of broadly neutralizing HIV antibodies for the treatment of HIV infection, particularly infection with multiple-drug-resistant isolates.While broadly neutralizing human immunodeficiency virus (HIV)-specific antibodies have the capacity to prevent or suppress HIV infection, they are rarely produced by infected individuals, thereby markedly compromising the ability of the humoral response to control HIV infection (reviewed in reference 28). The high degree of sequence variability in the gp120 structure limits the number of highly conserved epitopes available for targeting by neutralizing antibodies (40). In addition, HIV utilizes several mechanisms to shield the limited number of conserved neutralizing epitopes from the potentially potent antiviral effects of HIV envelope-specific antibodies (14). First, the envelope protein is heavily glycosylated, and the linkage of the most immunoreactive envelope peptide structures to poorly immunogenic glycans shields them from antibody binding (37). Second, exposure of neutralizing epitopes not protected from antibody binding by glycosylation is greatly reduced by trimerization of the gp120-gp41 structure (5). Third, susceptibility of other neutralizing epitopes to antibodies is greatly reduced by limiting their accessibility to antibody binding to the brief transient phase of conformational changes that occur only during binding of the envelope protein to its cellular receptors, CD4 and CCR5 or CXCR4 (41). These intrinsic structural features of gp120 greatly reduce the capacity of natural HIV infection or vaccination to generate broadly neutralizing antibodies able to prevent or control infection. Despite these constraints, rare human antibodies with broad anti-HIV neutralizing activity, i.e., 2G12, b12, 2F5, and 4E10, have been isolated (2).The capacity of passive immunization with neutralizing antibodies to prevent infection was suggested by challenge studies demonstrating that transferred neutralizing antibodies protected monkeys from infection by simian immunodeficiency virus (SIV) and simian-human immunodeficiency virus (SHIV) (15). These studies were extended to humans, including several studies that examined the effect of passive immunotherapy using 2G12, 2F5, and 4E10 on inhibition of HIV replication in infected individuals (20). Passive immunotherapy with a triple combination of 2G12, 2F5, and 4E10 delayed viral rebound after the cessation of highly active antiretroviral therapy (HAART), and activity of 2G12 was critical for inhibitory activity by this antibody combination (18). The key role of 2G12 in suppressing HIV replication was supported by the development of viral rebound in parallel with the emergence of HIV isolates resistant to neutralization by 2G12 (19).While HIV infection may be controlled by the lifelong treatment of HIV-infected individuals with periodic infusions of neutralizing-antibody cocktails every few weeks, this is not a practical or cost-effective therapeutic approach. Eliciting these antibodies by vaccination has not been successful. Therefore, we investigated whether we could circumvent the mechanisms that limit the endogenous production of broadly neutralizing HIV-specific antibodies using a molecular genetic approach to generate B cells that secrete these protective antibodies. In a proof-of-concept study, we examined the capacity of a single lentiviral vector to express the heavy and light chains of the 2G12 antibody, a well-studied anti-HIV human antibody that has broad neutralizing activity both against T cell line-adapted and primary HIV isolates (31). The 2G12 antibody was generated by applying murine/human xenohybridoma technology to establish human hybridoma cell lines from B cells isolated from HIV-infected individuals (16), and it targets the high-mannose and/or hybrid glycans of residues 295, 332, and 392 and peripheral glycans from residues 386 and 448 on gp120. In the current study we demonstrated that a lentiviral vector encoding the heavy and light chains of the 2G12 antibody reprogrammed B cells in vitro to secrete 2G12 with functional neutralizing activity. Furthermore, we demonstrated that the 2G12 lentiviral vector genetically modified human hematopoietic stem cells (hu-HSC), enabling them to differentiate in vivo into progeny cells that secreted 2G12 antibody that inhibited the development of in vivo HIV infection in humanized mice.