Brain-derived neurotrophic factor (BDNF) regulates diverse biological functions ranging from neuronal survival and differentiation during development to synaptic plasticity and cognitive behavior in the adult. BDNF disruption in both rodents and humans is associated with neurobehavioral alterations and psychiatric disorders. A unique feature of Bdnf transcription is regulation by nine individual promoters, which drive expression of variants that encode an identical protein. It is hypothesized that this unique genomic structure may provide flexibility that allows different factors to regulate BDNF signaling in distinct cell types and circuits. This has led to the suggestion that isoforms may regulate specific BDNF-dependent functions; however, little scientific support for this idea exists. We generated four novel mutant mouse lines in which BDNF production from one of the four major promoters (I, II, IV, or VI) is selectively disrupted (Bdnf-e1, -e2, -e4, and -e6 mice) and used a comprehensive comparator approach to determine whether different Bdnf transcripts are associated with specific BDNF-dependent molecular, cellular, and behavioral phenotypes. Bdnf-e1 and -e2 mutant males displayed heightened aggression accompanied by convergent expression changes in specific genes associated with serotonin signaling. In contrast, BDNF-e4 and -e6 mutants were not aggressive but displayed impairments associated with GABAergic gene expression. Moreover, quantifications of BDNF protein in the hypothalamus, prefrontal cortex, and hippocampus revealed that individual Bdnf transcripts make differential, regionspecific contributions to total BDNF levels. The results highlight the biological significance of alternative Bdnf transcripts and provide evidence that individual isoforms serve distinct molecular and behavioral functions.

Diazepam (Valium) is among the most successful drugs from the onset of the psychopharmacological revolution that began during the 1950s. Efficacious in treating a wide-spectrum of CNS disorders, including anxiety and epilepsy, it set the standard for pharmacotherapy in terms of potency, onset of action, and safety. In this Review, the legacy of diazepam to chemical neuroscience will be considered along with its synthesis, pharmacology, drug metabolism, adverse events and dependence, clinical use, and regulatory issues.

Severe acute respiratory syndrome (SARS) is a highly contagious disease, caused by SARS coronavirus (SARS-CoV), for which there are no approved treatments. We report the discovery of a potent inhibitor of SARS-CoV that blocks replication by inhibiting the unwinding activity of the SARS-CoV helicase (nsp13). We used a Förster resonance energy transfer (FRET)-based helicase assay to screen the Maybridge Hitfinder chemical library. We identified and validated a compound (SSYA10-001) that specifically blocks the double-stranded RNA (dsRNA) and dsDNA unwinding activities of nsp13, with 50% inhibitory concentrations (IC 50 s) of 5.70 and 5.30 M, respectively. This compound also has inhibitory activity (50% effective concentration [EC 50 ] ‫؍‬ 8.95 M) in a SARS-CoV replicon assay, with low cytotoxicity (50% cytotoxic concentration [CC 50 ] ‫؍‬ >250 M), suggesting that the helicase plays a still unidentified critical role in the SARS-CoV life cycle. Enzyme kinetic studies on the mechanism of nsp13 inhibition revealed that SSYA10-001 acts as a noncompetitive inhibitor of nsp13 with respect to nucleic acid and ATP substrates. Moreover, SSYA10-001 does not affect ATP hydrolysis or nsp13 binding to the nucleic acid substrate. SSYA10-001 did not inhibit hepatitis C virus (HCV) helicase, other bacterial and viral RNA-dependent RNA polymerases, or reverse transcriptase. These results suggest that SSYA10-001 specifically blocks nsp13 through a novel mechanism and is less likely to interfere with the functions of cellular enzymes that process nucleic acids or ATP. Hence, it is possible that SSYA10-001 inhibits unwinding by nsp13 by affecting conformational changes during the course of the reaction or translocation on the nucleic acid. SSYA10-001 will be a valuable tool for studying the specific role of nsp13 in the SARS-CoV life cycle, which could be a model for other nidoviruses and also a candidate for further development as a SARS antiviral target. Severe acute respiratory syndrome coronavirus (SARS-CoV) is responsible for the life-threatening viral respiratory illness known as SARS, which emerged from Southern China in November 2002 and spread to other parts of the world, including North America, South America, and Europe (50, 64). There is currently no approved therapeutic agent for the treatment of SARS-CoV infections. Although SARS currently does not pose a public health threat, the likelihood of future occurrences of both SARS-CoV and related viruses necessitates continuous research for identification of antiviral therapies.SARS-CoV contains a single-stranded, 5=-capped, polyadenylated positive-strand RNA genome that is ϳ29.7 kb long (40,45). The first open reading frame (ORF1a/b) encompasses about twothirds of the genome and codes for the replicase proteins (41). Following a Ϫ1 frameshift signal, translation continues in ORF1b after initiation at ORF1a. The virally encoded chymotrypsin-like protease 3CLpro (also called M pro or main protease) and the papain-like protease (PLP) cleave (by autoproteolysis) the newly form...

Disruption of the laminar and columnar organization of the brain is implicated in several psychiatric disorders. Here, we show in utero gain-of-function of the psychiatric risk gene transcription factor 4 (TCF4) severely disrupts the columnar organization of medial prefrontal cortex (mPFC) in a transcription- and activity-dependent manner. This morphological phenotype was rescued by co-expression of TCF4 plus calmodulin in a calcium-dependent manner and by dampening neuronal excitability through co-expression of the inwardly rectifying potassium channel (Kir2.1). For the first time, we show that NMDA receptor-dependent Ca2+ transients are instructive to minicolumn organization because Crispr/Cas9-mediated mutation of NMDA receptors rescued TCF4-dependent morphological phenotypes. Furthermore, we demonstrate that the transcriptional regulation by the psychiatric risk gene TCF4 enhances NMDA receptor-dependent early network oscillations. Our novel findings indicate that TCF4-dependent transcription directs the proper formation of prefrontal cortical minicolumns by regulating the expression of genes involved in early spontaneous neuronal activity, and thus our results provides insights into potential pathophysiological mechanisms of TCF4 associated psychiatric disorders.

The primate-specific brain voltage-gated potassium channel isoform Kv11.1-3.1 has been identified as a novel therapeutic target for the treatment of schizophrenia. While this ether-a-go-go related K + channel has shown clinical relevance, drug discovery efforts have been hampered due to low and inconsistent activity in cell-based assays. This poor activity is hypothesized to result from poor trafficking via the lack of an intact channel-stabilizing Per-Ant-Sim (PAS) domain. Here we characterize Kv11.1-3.1 cellular localization and show decreased channel expression and cell surface trafficking relative to the PAS-domain containing major isoform, Kv11.1-1A. Using small molecule inhibition of proteasome degradation, cellular expression and plasma membrane trafficking are rescued. These findings implicate the importance of the unfolded-protein response and endoplasmic reticulum associated degradation pathways in the expression and regulation of this schizophrenia risk factor. Utilizing this identified phenomenon, an electrophysiological and high throughput in-vitro fluorescent assay platform has been developed for drug discovery in order to explore a potentially new class of cognitive therapeutics.

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