Mechanisms of amphetamine action illuminated through optical monitoring of dopamine synaptic vesicles in Drosophila brain

Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT’s role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H+ antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects

Stable isotope and minor element proxies for Eocene climate of Seymour Island, Antarctica

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94846/1/palo900.pd

Anthrax Edema Toxin Modulates PKA- and CREB-Dependent Signaling in Two Phases

Background: Anthrax edema toxin (EdTx) is an adenylate cyclase which operates in the perinuclear region of host cells. However, the action of EdTx is poorly understood, especially at molecular level. The ability of EdTx to modulate cAMPdependent signaling was studied in Jurkat T cells and was compared with that of other cAMP-rising agents: Bordetella pertussis adenylate cyclase toxin, cholera toxin and forskolin. Methodology/Principal Findings: EdTx caused a prolonged increase of the intracellular cAMP concentration. This led to nuclear translocation of the cAMP-dependent protein kinase (PKA) catalytic subunit, phosphorylation of cAMP response element binding protein (CREB) and expression of a reporter gene under control of the cAMP response element. Neither p90 ribosomal S6 kinase nor mitogen- and stress-activated kinase, which mediate CREB phosphorylation during T cell activation, were involved. The duration of phospho-CREB binding to chromatin correlated with the spatio-temporal rise of cAMP levels. Strikingly, EdTx pre-treated T cells were unresponsive to other stimuli involving CREB phosphorylation such as addition of forskolin or T cell receptor cross-linking. Conclusions/Significance: We concluded that, in a first intoxication phase, EdTx induces PKA-dependent signaling, which culminates in CREB phosphorylation and activation of gene transcription. Subsequently CREB phosphorylation is impaired and therefore T cells are not able to respond to cues involving CREB. The present data functionally link the perinuclea

An Integrated Approach for a Structural and Functional Evaluation of Biosimilars: Implications for Erythropoietin

BACKGROUND: Authorization to market a biosimilar product by the appropriate institutions is expected based on biosimilarity with its originator product. The analogy between the originator and its biosimilar(s) is assessed through safety, purity, and potency analyses. OBJECTIVE: In this study, we proposed a useful quality control system for rapid and economic primary screening of potential biosimilar drugs. For this purpose, chemical and functional characterization of the originator rhEPO alfa and two of its biosimilars was discussed. METHODS: Qualitative and quantitative analyses of the originator rhEPO alfa and its biosimilars were performed using reversed-phase high-performance liquid chromatography (RP-HPLC). The identification of proteins and the separation of isoforms were studied using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF–MS) and two-dimensional gel electrophoresis (2D-PAGE), respectively. Furthermore, the biological activity of these drugs was measured both in vitro, evaluating the TF-1 cell proliferation rate, and in vivo, using the innovative experimental animal model of the zebrafish embryos. RESULTS: Chemical analyses showed that the quantitative concentrations of rhEPO alfa were in agreement with the labeled claims by the corresponding manufacturers. The qualitative analyses performed demonstrated that the three drugs were pure and that they had the same amino acid sequence. Chemical differences were found only at the level of isoforms containing N-glycosylation; however, functional in vitro and in vivo studies did not show any significant differences from a biosimilar point of view. CONCLUSION: These rapid and economic structural and functional analyses were effective in the evaluation of the biosimilarity between the originator rhEPO alfa and the biosimilars analyzed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40259-015-0136-3) contains supplementary material, which is available to authorized users

Identification of regulatory variants associated with genetic susceptibility to meningococcal disease.

Non-coding genetic variants play an important role in driving susceptibility to complex diseases but their characterization remains challenging. Here, we employed a novel approach to interrogate the genetic risk of such polymorphisms in a more systematic way by targeting specific regulatory regions relevant for the phenotype studied. We applied this method to meningococcal disease susceptibility, using the DNA binding pattern of RELA - a NF-kB subunit, master regulator of the response to infection - under bacterial stimuli in nasopharyngeal epithelial cells. We designed a custom panel to cover these RELA binding sites and used it for targeted sequencing in cases and controls. Variant calling and association analysis were performed followed by validation of candidate polymorphisms by genotyping in three independent cohorts. We identified two new polymorphisms, rs4823231 and rs11913168, showing signs of association with meningococcal disease susceptibility. In addition, using our genomic data as well as publicly available resources, we found evidences for these SNPs to have potential regulatory effects on ATXN10 and LIF genes respectively. The variants and related candidate genes are relevant for infectious diseases and may have important contribution for meningococcal disease pathology. Finally, we described a novel genetic association approach that could be applied to other phenotypes