Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Meta-analyses of genome-wide association studies for postpartum depression

Objective: Postpartum depression (PPD) is a common subtype of major depressive disorder (MDD) that is more heritable, yet is understudied in psychiatric genetics. The authors conducted meta-analyses of genome-wide association studies (GWASs) to investigate the genetic architecture of PPD. Method: Meta-analyses were conducted on 18 cohorts of European ancestry (17,339 PPD cases and 53,426 controls), one cohort of East Asian ancestry (975 cases and 3,780 controls), and one cohort of African ancestry (456 cases and 1,255 controls), totaling 18,770 PPD cases and 58,461 controls. Post-GWAS analyses included 1) single-nucleotide polymorphism (SNP)–based heritability (), 2) genetic correlations between PPD and other phenotypes, and 3) enrichment of the PPD GWAS findings in 27 human tissues and 265 cell types from the mouse central and peripheral nervous system. Results: No SNP achieved genome-wide significance in the European or the trans-ancestry meta-analyses. The of PPD was 0.14 (SE=0.02). Significant genetic correlations were estimated for PPD with MDD, bipolar disorder, anxiety disorders, posttraumatic stress disorder, insomnia, age at menarche, and polycystic ovary syndrome. Cell-type enrichment analyses implicate inhibitory neurons in the thalamus and cholinergic neurons within septal nuclei of the hypothalamus, a pattern that differs from MDD. Conclusions: While more samples are needed to reach genome-wide levels of significance, the results presented confirm PPD as a polygenic and heritable phenotype. There is also evidence that despite a high correlation with MDD, PPD may have unique genetic components. Cell enrichment results suggest GABAergic neurons, which converge on a common mechanism with the only medication approved by the U.S. Food and Drug Administration for PPD (brexanolone)

Recent Advances in the Discovery of Selective and Non-Selective 5-HT1D Receptor Ligands

This article highlights recent advances in the discovery of new agonists, antagonists and partial agonists of the 5-HT1D receptor. The field of 5-HT1D agonists continues to deliver a number of new potential therapeutic agents, although advances in this field are now more focussed on the clinical evaluation phase. The identification of novel compounds is greater for the 5-HT1D receptor antagonists, and whilst few truly selective ligands have been identified, a number of approaches are discussed towards defined mixed-pharmacology profiles. An overview is also given of recent advances in biological and clinical understanding of the receptor

Recent advances in the discovery of selective and non-selective 5-HT1D receptor ligands

This article highlights recent advances in the discovery of new agonists, antagonists and partial agonists of the 5-HT1D receptor. The field of 5-HT1D agonists continues to deliver a number of new potential therapeutic agents, although advances in this field are now more focussed on the clinical evaluation phase. The identification of novel compounds is greater for the 5-HT1D receptor antagonists, and whilst few truly selective ligands have been identified, a number of approaches are discussed towards defined mixed-pharmacology profiles. An overview is also given of recent advances in biological and clinical understanding of the receptor

Effects of positive allosteric modulators on single-cell oscillatory Ca2+ signaling initiated by the type 5 metabotropic glutamate receptor

Agonist stimulation of the type 5 metabotropic glutamate (mGlu5) receptor initiates robust oscillatory changes in cytosolic Ca2+ concentration ([Ca2+]i) in single cells by rapid, repeated cycles of phosphorylation/dephosphorylation of the mGlu5 receptor, involving protein kinase C and as-yet-unspecified protein phosphatase activities. An emergent property of this type of Ca2+ oscillation-generating mechanism (termed “dynamic uncoupling”) is that once a threshold concentration has been reached to initiate the Ca2+ oscillation, its frequency is largely insensitive to further increases in orthosteric agonist concentration. Here, we report the effects of positive allosteric modulators (PAMs) on the patterns of single-cell Ca2+ signaling in recombinant and native mGlu5 receptor-expressing systems. In a Chinese hamster ovary cell-line (CHO-lac-mGlu5a), none of the mGlu5 receptor PAMs studied [3,3′-difluorobenzaldazine (DFB), N-{4-chloro-2-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl) methyl]phenyl}-2-hydroxy-benzamide (CPPHA), 3-cyano-N-(1, 3-diphenyl-1H-prazol-5-yl)benzamide (CDPPB), S-(4-fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]oxadiazol-5-yl]-piperidinl-1-yl}-methanone (ADX47273)], stimulated a Ca2+ response when applied alone, but each PAM concentration-dependently increased the frequency, without affecting the amplitude, of Ca2+ oscillations induced by glutamate or quisqualate. Therefore, PAMs can cause graded increases (and negative allosteric modulator-graded decreases) in the Ca2+ oscillation frequency stimulated by orthosteric agonist. Initial data in rat cerebrocortical astrocytes demonstrated that similar effects of PAMs could be observed in a native cell background, although at high orthosteric agonist concentrations, PAM addition could much more often be seen to drive rapid Ca2+ oscillations into peak-plateau responses. These data demonstrate that allosteric modulators can “tune” the Ca2+ oscillation frequency initiated by mGlu5 receptor activation, and this might allow pharmacological modification of the downstream processes (e.g., transcriptional regulation) that is unachievable through orthosteric ligand interactions

Discovery of the first potent, selective 5-Hydroxytryptamine1D receptor antagonist [Letter]

A series of 5-(piperidinylethyloxy)quinoline 5-hydroxytryptamine1D (5-HT1D) receptor antagonists have been discovered from elaboration of the series of dual 5-hydroxytryptamine1−selective serotonin reuptake inhibitors (5HT1−SSRIs) reported previously. This is the first report of highly potent, selective antagonists for the 5-HT1D receptor, which represents an extremely useful set of pharmacological tools for further understanding the roles of the 5-HT1 receptor subtypes

Distinct muscarinic acetylcholine receptor subtypes mediate pre- and postsynaptic effects in rat neocortex

<p>Abstract</p> <p>Background</p> <p>Cholinergic transmission has been implicated in learning, memory and cognition. However, the cellular effects induced by muscarinic acetylcholine receptors (mAChRs) activation are poorly understood in the neocortex. We investigated the effects of the cholinergic agonist carbachol (CCh) and various agonists and antagonists on neuronal activity in rat neocortical slices using intracellular (sharp microelectrode) and field potential recordings.</p> <p>Results</p> <p>CCh increased neuronal firing but reduced synaptic transmission. The increase of neuronal firing was antagonized by pirenzepine (M₁/M₄ mAChRs antagonist) but not by AF-DX 116 (M₂/M₄ mAChRs antagonist). Pirenzepine reversed the depressant effect of CCh on excitatory postsynaptic potential (EPSP) but had marginal effects when applied before CCh. AF-DX 116 antagonized the depression of EPSP when applied before or during CCh. CCh also decreased the paired-pulse inhibition of field potentials and the inhibitory conductances mediated by GABA_A and GABA_B receptors. The depression of paired-pulse inhibition was antagonized or prevented by AF-DX 116 or atropine but only marginally by pirenzepine. The inhibitory conductances were unaltered by xanomeline (M₁/M₄ mAChRs agonist), yet the CCh-induced depression was antagonized by AF-DX 116. Linopirdine, a selective M-current blocker, mimicked the effect of CCh on neuronal firing. However, linopirdine had no effect on the amplitude of EPSP or on the paired-pulse inhibition, indicating that M-current is involved in the increase of neuronal excitability but neither in the depression of EPSP nor paired-pulse inhibition.</p> <p>Conclusions</p> <p>These data indicate that the three effects are mediated by different mAChRs, the increase in firing being mediated by M₁ mAChR, decrease of inhibition by M₂ mAChR and depression of excitatory transmission by M₄ mAChR. The depression of EPSP and increase of neuronal firing might enhance the signal-to-noise ratio, whereas the concomitant depression of inhibition would facilitate long-term potentiation. Thus, this triade of effects may represent a “neuronal correlate” of attention and learning.</p

The potent M1 receptor allosteric agonist GSK1034702 improves episodic memory in humans in the nicotine abstinence model of cognitive dysfunction

Episodic memory deficits are a core feature of neurodegenerative disorders. Muscarinic M1 receptors play a critical role in modulating learning and memory and are highly expressed in the hippocampus. We examined the effect of GSK1034702, a potent M1 receptor allosteric agonist, on cognitive function, and in particular episodic memory, in healthy smokers using the nicotine abstinence model of cognitive dysfunction. The study utilized a randomized, double-blind, placebo-controlled, cross-over design in which 20 male nicotine abstained smokers were tested following single doses of placebo, 4 and 8 mg GSK1034702. Compared to the baseline (nicotine on-state), nicotine abstinence showed statistical significance in reducing immediate (p=0.019) and delayed (p=0.02) recall. GSK1034702 (8 mg) significantly attenuated (i.e. improved) immediate recall (p=0.014) but not delayed recall. None of the other cognitive domains was modulated by either nicotine abstinence or GSK1034702. These findings suggest that stimulating M1 receptor mediated neurotransmission in humans with GSK1034702 improves memory encoding potentially by modulating hippocampal function. Hence, selective M1 receptor allosteric agonists may have therapeutic benefits in disorders of impaired learning including Alzheimer\u27s disease

Quantitative Analysis Reveals Multiple Mechanisms of Allosteric Modulation of the mGlu5 Receptor in Rat Astroglia

Positive and negative allosteric modulators (PAMs and NAMs, respectively) of the type 5 metabotropic glutamate (mGlu5) receptor have demonstrable therapeutic potential in an array of neurological and psychiatric disorders. Here, we have used rat cortical astrocytes to investigate how PAMs and NAMs mediate their activity and reveal marked differences between PAMs with respect to their modulation of orthosteric agonist affinity and efficacy. Affinity cooperativity factors (α) were assessed using [3H]2-methyl-6-(phenylethynyl)-pyridine (MPEP)-PAM competition binding in the absence and presence of orthosteric agonist, whereas efficacy cooperativity factors (β) were calculated from net affinity/efficacy cooperativity parameters (αβ) obtained from analyses of the abilities of PAMs to potentiate [3H]inositol phosphate accumulation in astrocytes stimulated with a submaximal (EC20) concentration of orthosteric agonist. We report that whereas 3,3′-difluorobenzaldazine (DFB) and 3-cyano-N-(1,3-diphenyl-1H-prazol-5-yl)benzamide (CDPPB) primarily exert their allosteric modulatory effects through modifying the apparent orthosteric agonist affinity at the astrocyte mGlu5 receptor, the effects of S-(4-fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]oxadiazol-5-yl]-piperidinl-1-yl}-methanone (ADX47273) are mediated primarily via efficacy-driven modulation. In [3H]MPEP-NAM competition binding assays, both MPEP and 2-(2-(3-methoxyphenyl)ethynyl)-5-methylpyridine (M-5MPEP) defined similar specific binding components, with affinities that were unaltered in the presence of orthosteric agonist, indicating wholly negative efficacy-driven modulations. It is noteworthy that whereas M-5MPEP only partially inhibited orthosteric agonist-stimulated [3H]inositol phosphate accumulation in astrocytes, it could completely suppress Ca2+ oscillations stimulated by quisqualate or (S)-3,5-dihydroxyphenylglycine. In contrast, MPEP was fully inhibitory with respect to both functional responses. The finding that M-5MPEP has different functional effects depending on the endpoint measured is discussed as a possible example of permissive allosteric antagonism