Multiple cytosolic components promote intra-Golgi protein transport. Resolution of a protein acting at a late stage, prior to membrane fusion

Cytosolic components are required to produce the "primed donor" and to consume the "dilution-resistant" intermediates of the intercompartmental protein transport pathway as elucidated in a cell-free system (Balch, W. E., Glick, B. S., and Rothman, J. E. (1984) Cell 39, 525-536, and Wattenberg, B. W., Balch, W. E., and Rothman, J. E. (1986) J. Biol. Chem. 261, 2202-2207). Widely different levels of crude cytosol are required for each of these steps, suggesting that different cytosolic components might mediate each step. Here, we fractionate cytosol and demonstrate that there are multiple transport-active components. Furthermore, we report the development of stage-specific functional assays which reveal that a distinct soluble component is required in the consumption of the dilution-resistant intermediate. This component, of about 25 kilodaltons in its apparent native molecular mass, is derived from calf brain cytosol. While this component mediates the consumption of the dilution-resistant intermediate, it is inactive in the priming stage. This stage-specific component seems likely to be involved in the processing of transport vesicles after the attachment of those vesicles to the target membranes.     

Correction to: Reevaluation of Astrocyte‑Neuron Energy Metabolism with Astrocyte Volume Fraction Correction: Impact on Cellular Glucose Oxidation Rates,Glutamate–Glutamine Cycle Energetics,Glycogen Levels and Utilization Rates vs. Exercising Muscle,and Na+/K+ Pumping Rates

Neurochemical Research -     

Disease-driven reduction in human mobility influences human-mosquito contacts and dengue transmission dynamics

Heterogeneous exposure to mosquitoes determines an individual’s contribution to vector-borne pathogen transmission. Particularly for dengue virus (DENV), there is a major difficulty in quantifying human-vector contacts due to the unknown coupled effect of key heterogeneities. To test the hypothesis that the reduction of human out-of-home mobility due to dengue illness will significantly influence population-level dynamics and the structure of DENV transmission chains, we extended an existing modeling framework to include social structure, disease-driven mobility reductions, and heterogeneous transmissibility from different infectious groups. Compared to a baseline model, naïve to human pre-symptomatic infectiousness and disease-driven mobility changes, a model including both parameters predicted an increase of 37% in the probability of a DENV outbreak occurring; a model including mobility change alone predicted a 15.5% increase compared to the baseline model. At the individual level, models including mobility change led to a reduction of the importance of out-of-home onward transmission (R, the fraction of secondary cases predicted to be generated by an individual) by symptomatic individuals (up to -62%) at the expense of an increase in the relevance of their home (up to +40%). An individual’s positive contribution to R could be predicted by a GAM including a non-linear interaction between an individual’s biting suitability and the number of mosquitoes in their home (>10 mosquitoes and 0.6 individual attractiveness significantly increased R). We conclude that the complex fabric of social relationships and differential behavioral response to dengue illness cause the fraction of symptomatic DENV infections to concentrate transmission in specific locations, whereas asymptomatic carriers (including individuals in their pre-symptomatic period) move the virus throughout the landscape. Our findings point to the difficulty of focusing vector control interventions reactively on the home of symptomatic individuals, as this approach will fail to contain virus propagation by visitors to their house and asymptomatic carriers.     

Novel ligands for the opioid receptors: synthesis and structure-activity relationships among 5'-aryl and 5'-heteroaryl 17-cyclopropylmethyl-4,5 alpha-epoxypyrido[2',3':6,7]morphinans

A series of pyridomorphinans possessing an aryl (10a-s) or heteroaryl (11a-h) substituent at the 5'-position of the pyridine ring of 17-cyclopropylmethyl-4,5 alpha-epoxypyrido[2',3':6,7]morphinan was synthesized and evaluated for binding and functional activity at the opioid delta, mu, and kappa receptors. All of these pyridomorphinans bound with higher affinity at the delta site than at mu or kappa sites. The binding data on isomeric compounds revealed that there exists greater bulk tolerance for substituents placed at the o-position of the phenyl ring than at m- or p-positions. Among the ligands examined, the 2-chlorophenyl (10l), 2-nitrophenyl (10n), 2-pyridyl (11a), and 4-quinolinyl (11g) compounds bound to the delta receptor with subnanomolar affinity. Compound 10c with the p-tolyl substituent displayed the highest mu/delta selectivity (ratio=42) whereas compound 10l with the 2-chlorophenyl substituent displayed the highest kappa/delta selectivity (ratio=23). At 10 microM concentration, the in vitro functional activity determined using [(35)S]GTP-gamma-S binding assays showed that all of the compounds were antagonists devoid of any significant agonist activity at the delta, mu, and kappa receptors. Antagonist potency determinations of three selected ligands revealed that the p-tolyl compound 10c is a potent delta selective antagonist. In the [(35)S]GTP-gamma-S assays this compound had a functional antagonist K(i) value of 0.2, 4.52, and 7.62 nM at the delta, mu, and kappa receptors, respectively. In the smooth muscle assays 10c displayed delta antagonist potency with a K(e) value of 0.88 nM. As an antagonist, it was 70-fold more potent at the delta receptors in the MVD than at the mu receptors in the GPI. The in vitro delta antagonist profile of this pyridomorphinan 10c resembles that of the widely used delta selective antagonist ligand naltrindole.     

Cell death: hook, line and linker

The programmed death of particular cells in Caenorhabditis elegans and Drosophila has been shown to occur by non-apoptotic programs regulated by developmental timing. Such alternative programs may be used as a general mechanism to eliminate differentiated, functional cells.     

DAT/SERT selectivity of flexible GBR 12909 analogs modeled using 3D-QSAR methods

The dopamine reuptake inhibitor GBR 12909 (1-{2-[bis(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)piperazine, 1) and its analogs have been developed as tools to test the hypothesis that selective dopamine transporter (DAT) inhibitors will be useful therapeutics for cocaine addiction. This 3D-QSAR study focuses on the effect of substitutions in the phenylpropyl region of 1. CoMFA and CoMSIA techniques were used to determine a predictive and stable model for the DAT/serotonin transporter (SERT) selectivity (represented by pK(i) (DAT/SERT)) of a set of flexible analogs of 1, most of which have eight rotatable bonds. In the absence of a rigid analog to use as a 3D-QSAR template, six conformational families of analogs were constructed from six pairs of piperazine and piperidine template conformers identified by hierarchical clustering as representative molecular conformations. Three models stable to y-value scrambling were identified after a comprehensive CoMFA and CoMSIA survey with Region Focusing. Test set correlation validation led to an acceptable model, with q(2)=0.508, standard error of prediction=0.601, two components, r(2)=0.685, standard error of estimate=0.481, F value=39, percent steric contribution=65, and percent electrostatic contribution=35. A CoMFA contour map identified areas of the molecule that affect pK(i) (DAT/SERT). This work outlines a protocol for deriving a stable and predictive model of the biological activity of a set of very flexible molecules.     

Probes for narcotic receptor mediated phenomena. Part 42: synthesis and in vitro pharmacological characterization of the N-methyl and N-phenethyl analogues of the racemic ortho-c and para-c oxide-bridged phenylmorphans

A new synthesis of N-methyl and N-phenethyl substituted ortho-c and para-c oxide-bridged phenylmorphans, using N-benzyl- rather than N-methyl-substituted intermediates, was used and the pharmacological properties of these compounds were determined. The N-phenethyl substituted ortho-c oxide-bridged phenylmorphan(rac-(3R,6aS,11aS)-2-phenethyl-2,3,4,5,6,11a-hexahydro-1H-3,6a-methanobenzofuro[2,3-c]azocin-10-ol (12)) was found to have the highest μ-opioid receptor affinity (K(i)=1.1 nM) of all of the a- through f-oxide-bridged phenylmorphans. Functional data ([3?S]GTP-γ-S) showed that the racemate 12 was more than three times more potent than naloxone as an μ-opioid antagonist.     

Genome-wide meta-analysis identifies regions on 7p21 (AHR) and 15q24 (CYP1A2) as determinants of habitual caffeine consumption

We report the first genome-wide association study of habitual caffeine intake. We included 47,341 individuals of European descent based on five population-based studies within the United States. In a meta-analysis adjusted for age, sex, smoking, and eigenvectors of population variation, two loci achieved genome-wide significance: 7p21 (P = 2.4 × 10(-19)), near AHR, and 15q24 (P = 5.2 × 10(-14)), between CYP1A1 and CYP1A2. Both the AHR and CYP1A2 genes are biologically plausible candidates as CYP1A2 metabolizes caffeine and AHR regulates CYP1A2.     

Nutritional geometry: gorillas prioritize non-protein energy while consuming surplus protein

It is widely assumed that terrestrial food webs are built on a nitrogen-limited base and consequently herbivores must compensate through selection of high-protein foods and efficient nitrogen retention. Like many folivorous primates, gorillas' diet selection supports this assumption, as they apparently prefer protein-rich foods. Our study of mountain gorillas (Gorilla beringei) in Uganda revealed that, in some periods, carbohydrate-rich fruits displace a large portion of protein-rich leaves in their diet. We show that non-protein energy (NPE) intake was invariant throughout the year, whereas protein intake was substantially higher when leaves were the major portion of the diet. This pattern of macronutrient intake suggests that gorillas prioritize NPE and, to achieve this when leaves are the major dietary item, they over-eat protein. The concentrations of protein consumed in relation to energy when leaves were the major portion of the diet were close to the maximum recommended for humans and similar to high-protein human weight-loss diets. By contrast, the concentrations of protein in relation to energy when gorillas ate fruit-dominated diets were similar to those recommended for humans. Our results question the generality of nitrogen limitation in terrestrial herbivores and provide a fascinating contrast with human macronutrient intake.