MicroCorrespondence

A conserved surface-exposed domain in major outer membrane proteins of pathogenic Pseudomonas and Branhamella species shares sequence homology with the calcium-binding repeats of the eukaryotic extracellular matrix protein thrombospondin     

Acetylcholine binding protein (AChBP) as template for hierarchical in silico screening procedures to identify structurally novel ligands for the nicotinic receptors

Hierarchical in silico screening protocols against the agonist bound acetylcholine binding protein (AChBP) crystal structure were efficient in identifying novel chemotypes for AChBP and the human α7 receptor. Two hit structures were cocrystallized with AChBP revealing intermolecular cation-π interactions with loop C but lacking intermolecular hydrogen bonding. The compounds act as competitive α7 receptor antagonists and as non-competitive α4β2 receptor inhibitors. These results underline the usability of AChBP in structure-based in silico screening strategies in finding novel scaffolds for the α7 receptor, but also illustrates some limitations of using AChBP as bait to find competitive α4β2 receptor ligands and α7 receptor agonists.     

N-Acylhydrazones as inhibitors of PDE10A

Cyclic nucleotide phosphodiesterases (PDEs) are represented by a large superfamily of enzymes. A series of hydrazone-based inhibitors was synthesized and shown to be novel, potent, and selective against PDE10A. Optimized compounds of this class were efficacious in animal models of schizophrenia and may be useful for the treatment of this disease.     

Occurrence of alfalfa (<Emphasis Type="Italic">Medicago sativa</Emphasis> L.) populations along roadsides in southern Manitoba,Canada and their potential role in intraspecific gene flow

Alfalfa is a highly outcrossing perennial species that can be noticed in roadsides as feral populations. There remains little information available on the extent of feral alfalfa populations in western Canadian prairies and their role in gene flow. The main objectives of this study were (a) to document the occurrence of feral alfalfa populations, and (b) to estimate the levels of outcrossing facilitated by feral populations. A roadside survey confirmed widespread occurrence of feral alfalfa populations, particularly in alfalfa growing regions. The feral populations were dynamic and their frequency ranged from 0.2 to 1.7 populations km⁻¹. In many cases, the nearest feral alfalfa population from alfalfa production field was located within a distance sufficient for outcrossing in alfalfa. The gene flow study confirmed that genes can move back and forth between feral and cultivated alfalfa populations. In this study, the estimated outcrossing levels were 62% (seed fields to feral), 78% (feral to seed fields), 82% (hay fields to feral) and 85% (feral to feral). Overall, the results show that feral alfalfa plants are prevalent in alfalfa producing regions in western Canada and they can serve as bridges for gene flow at landscape level. Management of feral populations should be considered, if gene flow is a concern. Emphasis on preventing seed spill/escapes and intentional roadside planting of alfalfa cultivars will be particularly helpful. Further, realistic and pragmatic threshold levels should be established for markets sensitive to the presence of GE traits.     

Mutations in cytoplasmic dynein lead to a Huntington's disease-like defect in energy metabolism of brown and white adipose tissues

The molecular motor dynein is regulated by the huntingtin protein, and Huntington's disease (HD) mutations of huntingtin disrupt dynein motor activity. Besides abnormalities in the central nervous system, HD animal models develop prominent peripheral pathology, with defective brown tissue thermogenesis and dysfunctional white adipocytes, but whether this peripheral phenotype is recapitulated by dynein dysfunction is unknown. Here, we observed prominently increased adiposity in mice harboring the legs at odd angles (Loa/+) or the Cramping mutations (Cra/+) in the dynein heavy chain gene. In Cra/+ mice, hyperadiposity occurred in the absence of energy imbalance and was the result of impaired norepinephrine-stimulated lipolysis. A similar phenotype was observed in 3T3L1 adipocytes upon chemical inhibition of dynein showing that loss of functional dynein leads to impairment of lipolysis. Ex vivo, dynein mutant adipose tissue displayed increased reactive oxygen species production that was, at least partially, responsible for the decreased cellular responses to norepinephrine and subsequent defect in stimulated lipolysis. Dynein mutation also affected norepinephrine efficacy to elicit a thermogenic response and led to morphological abnormalities in brown adipose tissue and cold intolerance in dynein mutant mice. Interestingly, protein levels of huntingtin were decreased in dynein mutant adipose tissue. Collectively, our results provide genetic evidence that dynein plays a key role in lipid metabolism and thermogenesis through a modulation of oxidative stress elicited by norepinephrine. This peripheral phenotype of dynein mutant mice is similar to that observed in various animal models of HD, lending further support for a functional link between huntingtin and dynein.     

Necessity of hippocampal neurogenesis for the therapeutic action of antidepressants in adult nonhuman primates

Background

Rodent studies show that neurogenesis is necessary for mediating the salutary effects of antidepressants. Nonhuman primate (NHP) studies may bridge important rodent findings to the clinical realm since NHP-depression shares significant homology with human depression and kinetics of primate neurogenesis differ from those in rodents. After demonstrating that antidepressants can stimulate neurogenesis in NHPs, our present study examines whether neurogenesis is required for antidepressant efficacy in NHPs.

Materials/Methodology

Adult female bonnets were randomized to three social pens (N = 6 each). Pen-1 subjects were exposed to control-conditions for 15 weeks with half receiving the antidepressant fluoxetine and the rest receiving saline-placebo. Pen-2 subjects were exposed to 15 weeks of separation-stress with half receiving fluoxetine and half receiving placebo. Pen-3 subjects 2 weeks of irradiation (N = 4) or sham-irradiation (N = 2) and then exposed to 15 weeks of stress and fluoxetine. Dependent measures were weekly behavioral observations and postmortem neurogenesis levels.

Results

Exposing NHPs to repeated separation stress resulted in depression-like behaviors (anhedonia and subordinance) accompanied by reduced hippocampal neurogenesis. Treatment with fluoxetine stimulated neurogenesis and prevented the emergence of depression-like behaviors. Ablation of neurogenesis with irradiation abolished the therapeutic effects of fluoxetine. Non-stressed controls had normative behaviors although the fluoxetine-treated controls had higher neurogenesis rates. Across all groups, depression-like behaviors were associated with decreased rates of neurogenesis but this inverse correlation was only significant for new neurons in the anterior dentate gyrus that were at the threshold of completing maturation.

Conclusion

We provide evidence that induction of neurogenesis is integral to the therapeutic effects of fluoxetine in NHPs. Given the similarity between monkeys and humans, hippocampal neurogenesis likely plays a similar role in the treatment of clinical depression. Future studies will examine several outstanding questions such as whether neuro-suppression is sufficient for producing depression and whether therapeutic neuroplastic effects of fluoxetine are specific to antidepressants.     

Protobacco Media Exposure and Youth Susceptibility to Smoking Cigarettes,Cigarette Experimentation,and Current Tobacco Use among US Youth

Purpose

Youth are exposed to many types of protobacco influences, including smoking in movies, which has been shown to cause initiation. This study investigates associations between different channels of protobacco media and susceptibility to smoking cigarettes, cigarette experimentation, and current tobacco use among US middle and high school students.

Methods

By using data from the 2012 National Youth Tobacco Survey, structural equation modeling was performed in 2013. The analyses examined exposure to tobacco use in different channels of protobacco media on smoking susceptibility, experimentation, and current tobacco use, accounting for perceived peer tobacco use.

Results

In 2012, 27.9% of respondents were never-smokers who reported being susceptible to trying cigarette smoking. Cigarette experimentation increased from 6.3% in 6th grade to 37.1% in 12th grade. Likewise, current tobacco use increased from 5.2% in 6th grade to 33.2% in 12th grade. Structural equation modeling supported a model in which current tobacco use is associated with exposure to static advertising through perception of peer use, and by exposure to tobacco use depicted on TV and in movies, both directly and through perception of peer use. Exposure to static advertising appears to directly increase smoking susceptibility but indirectly (through increased perceptions of peer use) to increase cigarette experimentation. Models that explicitly incorporate peer use as a mediator can better discern the direct and indirect effects of exposure to static advertising on youth tobacco use initiation.

Conclusions

These findings underscore the importance of reducing youth exposure to smoking in TV, movies, and static advertising.     

Enhanced CD8 T Cell Responses through GITR-Mediated Costimulation Resolve Chronic Viral Infection

Chronic infections are characterized by the inability to eliminate the persisting pathogen and often associated with functional impairment of virus-specific T-cell responses. Costimulation through Glucocorticoid-induced TNFR-related protein (GITR) can increase survival and function of effector T cells. Here, we report that constitutive expression of GITR-ligand (GITRL) confers protection against chronic lymphocytic choriomeningitis virus (LCMV) infection, accelerating recovery without increasing pathology. Rapid viral clearance in GITRL transgenic mice coincided with increased numbers of poly-functional, virus-specific effector CD8+ T cells that expressed more T-bet and reduced levels of the rheostat marker PD-1. GITR triggering also boosted the helper function of virus-specific CD4 T cells already early in the infection, as was evidenced by increased IL-2 and IFNγ production, and more expression of CD40L and T-bet. Importantly, CD4-depletion experiments revealed that the expanded pool of virus-specific effector CD8 T cells and the ensuing viral clearance in LCMV-infected GITRL tg mice was entirely dependent on CD4 T cells. We found no major differences for NK cell and regulatory T cell responses, whereas the humoral response to the virus was increased in GITRL tg mice, but only in the late phase of the infection when the virus was almost eradicated. Based on these findings, we conclude that enhanced GITR-triggering mediates its protective, anti-viral effect on the CD8 T cell compartment by boosting CD4 T cell help. As such, increasing costimulation through GITR may be an attractive strategy to increase anti-viral CTL responses without exacerbating pathology, in particular to persistent viruses such as HIV and HCV.