GluA2-lacking AMPA receptors in hippocampal CA1 cell synapses: evidence from gene-targeted mice

The GluA2 subunit in heteromeric alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor channels restricts Ca2+ permeability and block by polyamines, rendering linear the current-voltage relationship of these glutamate-gated cation channels. Although GluA2-lacking synaptic AMPA receptors occur in GABA-ergic inhibitory neurons, hippocampal CA1 pyramidal cell synapses are widely held to feature only GluA2 containing AMPA receptors. A controversy has arisen from reports of GluA2-lacking AMPA receptors at hippocampal CA3-to-CA1 cell synapses and a study contesting these findings. Here we sought independent evidence for the presence of GluA2-lacking AMPA receptors in CA1 pyramidal cell synapses by probing the sensitivity of their gated cation channels in wild-type (WT) mice and gene-targeted mouse mutants to philanthotoxin, a specific blocker of GluA2-lacking AMPA receptors. The mutants either lacked GluA2 for maximal philanthotoxin sensitivity, or, for minimal sensitivity, expressed GluA1 solely in a Q/R site-edited version or not at all. Our comparative electrophysiological analyses provide incontrovertible evidence for the presence in wild-type CA1 pyramidal cell synapses of GluA2-less AMPA receptor channels. This article is part of a Special Issue entitled “Calcium permeable AMPARs in synaptic plasticity and disease.

Characterization of infectious and defective cloned avian hepadnavirus genomes

The infectivity in vivo, replication competence in vitro, and expression of viral genes of several molecularly cloned duck hepatitis B virus (DHBV) genomes were investigated. In addition, replication competence, core protein expression, and secretion of viral proteins were investigated for a grey heron hepatitis B virus genome. Except two, all DHBV isolates tested induced a systemic infection in Pekin ducks when injected as cloned viral DNA into the liver. After transfection of chicken hepatoma cells, both defective DHBV genomes expressed intracellular nucleocapsid and pre-S envelope proteins and secreted DHBs/pre-S particles into the medium. One of the defective DHBV genomes and HHBV produced within the cells replicative intermediates encapsidated in core particles and secreted virions, whereas the other defective DHBV genome did not and was unable to efficiently encapsidate the RNA pregenome. Comparative sequence analysis was performed to identify potential amino acid changes in viral proteins of both defective DHBV genomes. The data obtained demonstrate that most cloned avian hepadnaviruses are infectious or replication competent and suggest defects in envelope, polymerase or encapsidation function, respectively, in two cloned DHBV genomes

Signalling through AMPA receptors on oligodendrocyte precursors promotes myelination by enhancing oligodendrocyte survival

Myelin, made by oligodendrocytes, is essential for rapid information transfer in the central nervous system. Oligodendrocyte precursors (OPs) receive glutamatergic synaptic input from axons but how this affects their development is unclear. Murine OPs in white matter express AMPA receptor (AMPAR) subunits GluA2, GluA3 and GluA4. We generated mice in which OPs lack both GluA2 and GluA3, or all three subunits GluA2/3/4, which respectively reduced or abolished AMPAR-mediated input to OPs. In both double- and triple-knockouts OP proliferation and number were unchanged but ~25% fewer oligodendrocytes survived in the subcortical white matter during development. In triple knockouts, this shortfall persisted into adulthood. The oligodendrocyte deficit resulted in ~20% fewer myelin sheaths but the average length, number and thickness of myelin internodes made by individual oligodendrocytes appeared normal. Thus, AMPAR-mediated signalling from active axons stimulates myelin production in developing white matter by enhancing oligodendrocyte survival, without influencing myelin synthesis per se

Causal interrogation of neuronal networks and behavior through virally transduced ivermectin receptors

© 2016 Obenhaus, Rozov, Bertocchi, Tang, Kirsch, Betz and Sprengel.The causal interrogation of neuronal networks involved in specific behaviors requires the spatially and temporally controlled modulation of neuronal activity. For long-term manipulation of neuronal activity, chemogenetic tools provide a reasonable alternative to short-term optogenetic approaches. Here we show that virus mediated gene transfer of the ivermectin (IVM) activated glycine receptor mutant GlyRα1AG can be used for the selective and reversible silencing of specific neuronal networks in mice. In the striatum, dorsal hippocampus, and olfactory bulb, GlyRα1AG promoted IVM dependent effects in representative behavioral assays. Moreover, GlyRα1AG mediated silencing had a strong and reversible impact on neuronal ensemble activity and c-Fos activation in the olfactory bulb. Together our results demonstrate that long-term, reversible and re- inducible neuronal silencing via GlyRα1AG is a promising tool for the interrogation of network mechanisms underlying the control of behavior and memory formation

Block of NMDA receptor channels by endogenous neurosteroids: implications for the agonist induced conformational states of the channel vestibule

N-methyl-D-aspartate receptors (NMDARs) mediate synaptic plasticity, and their dysfunction is implicated in multiple brain disorders. NMDARs can be allosterically modulated by numerous compounds, including endogenous neurosteroid pregnanolone sulfate. Here, we identify the molecular basis of the use-dependent and voltage-independent inhibitory effect of neurosteroids on NMDAR responses. The site of action is located at the extracellular vestibule of the receptor's ion channel pore and is accessible after receptor activation. Mutations in the extracellular vestibule in the SYTANLAAF motif disrupt the inhibitory effect of negatively charged steroids. In contrast, positively charged steroids inhibit mutated NMDAR responses in a voltage-dependent manner. These results, in combination with molecular modeling, characterize structure details of the open configuration of the NMDAR channel. Our results provide a unique opportunity for the development of new therapeutic neurosteroid-based ligands to treat diseases associated with dysfunction of the glutamate system

Impact of Anxiety During Hospitalization on the Clinical Outcome of Patients With Osteoporotic Thoracolumbar Vertebral Fracture

STUDY DESIGN: Multicenter prospective cohort study. OBJECTIVES: Anxiety in combination with osteoporotic vertebral compression fractures (OVCFs) of the spine remains understudied. The purpose of this study was to analyze whether anxiety has an impact on the short-term functional outcome of patients with an OVCF. Furthermore, a direct impact of the fracture on the patient's anxiety during hospitalization should be recognized. METHODS: All inpatients with an OVCF of the thoracolumbar spine from 2017 to 2020 were included. Trauma mechanism, analgetic medication, anti-osteoporotic therapy, timed-up-and-go test (TuG), mobility, Barthel index, Oswestry-Disability Index (ODI) and EQ5D-5L were documented.For statistical analysis, the U test, chi-square independence test, Spearman correlation, General Linear Model for repeated measures, Bonferroni analysis and Wilcoxon test were used. The item anxiety/depression of the EQ5D-5L was analyzed to describe the patients' anxiousness. RESULTS: Data from 518 patients from 17 different hospitals were evaluated. Fracture severity showed a significant correlation (r = .087, P = .0496) with anxiety. During the hospital stay, pain medication (P < .001), anti-osteoporotic medication (P < .001), and initiation of surgical therapy (P < .001) were associated with less anxiety. The anxiety of a patient at discharge was negatively related to the functional outcomes at the individual follow-up: TuG (P < .001), Barthel index (P < .001), ODI (P < .001) and EQ5D-5L (P < .001). CONCLUSIONS: Higher anxiety is associated with lower functional outcome after OVCF. The item anxiety/depression of the EQ5D-5L provides an easily accessible, quick and simple tool that can be used to screen for poor outcomes and may also offer the opportunity for a specific anxiety intervention

The Role of Short-Termism and Uncertainty Avoidance in Organizational Inaction on Climate Change: A Multi-Level Framework

Despite increasing pressure to deal with climate change, firms have been slow to respond with effective action. This article presents a multi-level framework for a better understanding of why many firms are failing to reduce their absolute greenhouse gas emissions, which contribute to climate change. The concepts of short-termism and uncertainty avoidance from research in psychology, sociology, and organization theory can explain the phenomenon of organizational inaction on climate change. Antecedents related to short-termism and uncertainty avoidance reinforce one another at three levels—individual, organizational, and institutional—and result in organizational inaction on climate change. The article also discusses the implications of this multi-level framework for research on corporate sustainability

Treatment and Outcome of Osteoporotic Thoracolumbar Vertebral Body Fractures With Deformation of Both Endplates With or Without Posterior Wall Involvement (OF 4): Short-Term Results from the Prospective EOFTT Multicenter Study.

STUDY DESIGN: Multicenter prospective cohort study. OBJECTIVE: To analyse therapeutical strategies applied to osteoporotic thoracolumbar OF 4 injuries, to assess related complications and clinical outcome. METHODS: A multicenter prospective cohort study (EOFTT) including 518 consecutive patients who were treated for an Osteoporotic vertebral compression fracture (OVCF). For the present study, only patients with OF 4 fractures were analysed. Outcome parameters were complications, Visual Analogue Scale, Oswestry Disability Questionnaire, Timed Up & Go test, EQ-5D 5L, and Barthel Index after a minimum follow-up of 6 weeks. RESULTS: A total of 152 (29%) patients presented with OF 4 fractures with a mean age of 76 years (range 41-97). The most common treatment was short-segment posterior stabilization (51%; hybrid stabilization in 36%). Mean follow up was 208 days (±131 days), mean ODI was 30 ± 21. Dorsoventral stabilized patients were younger compared to the other groups (P .602, Barthel: P > .252, EQ-5D 5L index value: P > .610, VAS-EQ-5D 5L: P = 1.000). The inpatient complication rate was 8% after conservative and 16% after surgical treatment. During follow-up period 14% of conservatively treated patients and 3% of surgical treated patients experienced neurological deficits. CONCLUSIONS: Conservative therapy of OF 4 injuries seems to be viable option in patients with only moderate symptoms. Hybrid stabilization was the dominant treatment strategy leading to promising clinical short-term results. Stand-alone cement augmentation seems to be a valid alternative in selected cases

Evolution of GluN2A/B cytoplasmic domains diversified vertebrate synaptic plasticity and behavior

Two genome duplications early in the vertebrate lineage expanded gene families, including GluN2 subunits of the NMDA receptor. Diversification between the four mammalian GluN2 proteins occurred primarily at their intracellular C−terminal domains (CTDs). To identify shared ancestral functions and diversified subunit−specific functions, we exchanged the exons encoding the GluN2A (also known as Grin2a) and GluN2B (also known as Grin2b) CTDs in two knock−in mice and analyzed the mice's biochemistry, synaptic physiology, and multiple learned and innate behaviors. The eight behaviors were genetically separated into four groups, including one group comprising three types of learning linked to conserved GluN2A/B regions. In contrast, the remaining five behaviors exhibited subunit−specific regulation. GluN2A/B CTD diversification conferred differential binding to cytoplasmic MAGUK proteins and differential forms of long−term potentiation. These data indicate that vertebrate behavior and synaptic signaling acquired increased complexity from the duplication and diversification of ancestral GluN2 gene

Development of a Chromosomally Integrated Metabolite-Inducible Leu3p-α-IPM “Off-On” Gene Switch

Background: Present technology uses mostly chimeric proteins as regulators and hormones or antibiotics as signals to induce spatial and temporal gene expression. Methodology/Principal Findings: Here, we show that a chromosomally integrated yeast ‘Leu3p-a-IRM ’ system constitutes a ligand-inducible regulatory ‘‘off-on’ ’ genetic switch with an extensively dynamic action area. We find that Leu3p acts as an active transcriptional repressor in the absence and as an activator in the presence of a-isopropylmalate (a-IRM) in primary fibroblasts isolated from double transgenic mouse embryos bearing ubiquitously expressing Leu3p and a Leu3p regulated GFP reporter. In the absence of the branched amino acid biosynthetic pathway in animals, metabolically stable a-IPM presents an EC 50 equal to 0.8837 mM and fast ‘‘OFF-ON’ ’ kinetics (t 50ON = 43 min, t 50OFF = 2.18 h), it enters the cells via passive diffusion, while it is non-toxic to mammalian cells and to fertilized mouse eggs cultured ex vivo. Conclusions/Significance: Our results demonstrate that the ‘Leu3p-a-IRM ’ constitutes a simpler and safer system for inducible gene expression in biomedical applications