Selective inhibition of phosphodiesterases 4, 5 and 9 induces HSP20 phosphorylation and attenuates amyloid beta 1-42 mediated cytotoxicity

Phosphodiesterase (PDE) inhibitors are currently under evaluation as agents that may facilitate the improvement of cognitive impairment associated with Alzheimer's disease. Our aim was to determine whether inhibitors of PDEs 4,5 and 9 could alleviate the cytotoxic effects of amyloid beta 1–42 (Aβ1-42) via a mechanism involving the small heatshock protein HSP20. We show that inhibition of PDEs 4,5 and 9 but not 3 induces the phosphorylation of HSP20 which, in turn, increases the co-localisation between the chaperone and Aβ1-42 to significantly decrease the toxic effect of the peptide. We conclude that inhibition of PDE9 is most effective to combat Aβ1-42 cytotoxicity in our cell model

Should Symbionts Be Nice or Selfish? Antiviral Effects of Wolbachia Are Costly but Reproductive Parasitism Is Not.

Symbionts can have mutualistic effects that increase their host's fitness and/or parasitic effects that reduce it. Which of these strategies evolves depends in part on the balance of their costs and benefits to the symbiont. We have examined these questions in Wolbachia, a vertically transmitted endosymbiont of insects that can provide protection against viral infection and/or parasitically manipulate its hosts' reproduction. Across multiple symbiont strains we find that the parasitic phenotype of cytoplasmic incompatibility and antiviral protection are uncorrelated. Strong antiviral protection is associated with substantial reductions in other fitness-related traits, whereas no such trade-off was detected for cytoplasmic incompatibility. The reason for this difference is likely that antiviral protection requires high symbiont densities but cytoplasmic incompatibility does not. These results are important for the use of Wolbachia to block dengue virus transmission by mosquitoes, as natural selection to reduce these costs may lead to reduced symbiont density and the loss of antiviral protection.This study was funded by the Wellcome Trust grant WT094664MA (http://www.wellcome.ac.uk/). FMJ is supported by a Royal Society Research Fellowship.This is the final published version. It first appeared at http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005021

Structure of the master regulator Rns reveals an inhibitor of enterotoxigenic Escherichia coli virulence regulons

Enteric infections caused by the gram-negative bacteria enterotoxigenic Escherichia coli (ETEC), Vibrio cholerae, Shigella flexneri, and Salmonella enterica are among the most common and affect billions of people each year. These bacteria control expression of virulence factors using a network of transcriptional regulators, some of which are modulated by small molecules as has been shown for ToxT, an AraC family member from V. cholerae. In ETEC the expression of many types of adhesive pili is dependent upon the AraC family member Rns. We present here the 3 Å crystal structure of Rns and show it closely resembles ToxT. Rns crystallized as a dimer via an interface similar to that observed in other dimeric AraC’s. Furthermore, the structure of Rns revealed the presence of a ligand, decanoic acid, that inhibits its activity in a manner similar to the fatty acid mediated inhibition observed for ToxT and the S. enterica homologue HilD. Together, these results support our hypothesis that fatty acids regulate virulence controlling AraC family members in a common manner across a number of enteric pathogens. Furthermore, for the first time this work identifies a small molecule capable of inhibiting the ETEC Rns regulon, providing a basis for development of therapeutics against this deadly human pathogen

An Investigation into Genetic Associations with Musculoskeletal Soft Tissue Injuries in Elite Rugby – Preliminary Findings

Peer reviewe

SUMOylation of DISC1: a potential role in neural progenitor proliferation in the developing cortex

DISC1 is a multifunctional, intracellular scaffold protein. At the cellular level, DISC1 plays a pivotal role in neural progenitor proliferation, migration, and synaptic maturation. Perturbation of the biological pathways involving DISC1 is known to lead to behavioral changes in rodents, which supports a clinical report of a Scottish pedigree in which the majority of family members with disruption of the DISC1 gene manifest depression, schizophrenia, and related mental conditions. The discrepancy between modest evidence in genetics and strong biological support for the role of DISC1 in mental conditions suggests a working hypothesis that regulation of DISC1 at the protein level, such as posttranslational modification, may play a role in the pathology of mental conditions. In this study, we report on the SUMOylation of DISC1. This posttranslational modification occurs on lysine residues where the small ubiquitin-related modifier (SUMO) and its homologs are conjugated to a large number of cellular proteins, which in turn regulates their subcellular distribution and protein stability. By using in silico, biochemical, and cell-biological approaches, we now demonstrate that human DISC1 is SUMOylated at one specific lysine 643 (K643). We also show that this residue is crucial for proper neural progenitor proliferation in the developing cortex

Dimerization of cAMP phosphodiesterase-4 (PDE4) in living cells requires interfaces located in both the UCR1 and catalytic unit domains

PDE4 family cAMP phosphodiesterases play a pivotal role in determining compartmentalised cAMP signalling through targeted cAMP breakdown. Expressing the widely found PDE4D5 isoform, as both bait and prey in a yeast 2-hybrid system, we demonstrated interaction consistent with the notion that long PDE4 isoforms form dimers. Four potential dimerization sites were uncovered using a scanning peptide array approach, where a recombinant purified PDE4D5 fusion protein was used to probe a 25-mer library of overlapping peptides covering the entire PDE4D5 sequence. Key residues involved in PDE4D5 dimerization were defined using a site-directed mutagenesis programme directed by an alanine scanning peptide array approach. Critical residues stabilising PDE4D5 dimerization were defined within the regulatory UCR1 region found in long, but not short, PDE4 isoforms, namely the Arg173, Asn174 and Asn175 (DD1) cluster. Disruption of the DD1 cluster was not sufficient, in itself, to destabilise PDE4D5 homodimers. Instead, disruption of an additional interface, located on the PDE4 catalytic unit, was also required to convert PDE4D5 into a monomeric form. This second dimerization site on the conserved PDE4 catalytic unit is dependent upon a critical ion pair interaction. This involves Asp463 and Arg499 in PDE4D5, which interact in a trans fashion involving the two PDE4D5 molecules participating in the homodimer. PDE4 long isoforms adopt a dimeric state in living cells that is underpinned by two key contributory interactions, one involving the UCR modules and one involving an interface on the core catalytic domain. We propose that short forms do not adopt a dimeric configuration because, in the absence of the UCR1 module, residual engagement of the remaining core catalytic domain interface provides insufficient free energy to drive dimerization. The functioning of PDE4 long and short forms is thus poised to be inherently distinct due to this difference in quaternary structure

Bone Mineral Density and Associated Genetic Variants in High-level Caucasian Marathon Runners

INTRODUCTION:Endurance runners (except those who may have low energy availability) tend to have higher total and/or loading site-specific bone mineral density (BMD) in comparison with non-athletes, most likely due to the larger volume of exercise completed. A large genetic component also contributes to BMD, although little is known about which specific genes are involved, whether particular genotypes are sensitive to mechanical loading and the impact of such an interaction on BMD. This study investigated if high-level endurance runners possess enhanced BMD associated with an “advantageous” genetic predisposition, via a potential gene-physical activity interaction.METHODS:Age- and weight-adjusted total BMD (TBMD) and leg BMD (LBMD) measured via Dual-energy X-ray absorptiometry of 67 high-level Caucasian marathon runners (males < 2 h 45 min, n = 37; females < 3 15 min, n = 30) was compared with 40 male and 26 female non-athletes. LRP5 rs3736228, TNFRSF11B rs4355801, VDR rs2228570, WNT16 rs3801387 and AXIN1 rs9921222 variants were then investigated singularly, and collectively, as a total genotype score (TGS) via multivariate analysis of variance in a subgroup of this cohort (male runners n = 19, controls n = 26; female runners n = 17, controls n = 14). RESULTS:Male runners had higher TBMD (1.34 vs 1.28 g/cm2; P=0.02) and LBMD (1.53 vs 1.42 g/cm2; P=<0.01) than non-athletes. Female runners had higher LBMD than non-athletes (1.30 vs 1.22 g/cm2; P=0.02) but not TBMD (1.23 vs 1.18 g/cm2; P=0.22). An interaction (P=0.047) was observed between VDR rs2228570 genotype and group regarding LBMD in males: ff genotype runners had 0.02 g/cm2 higher LBMD than FF or Ff runners, but the FF genotype had the highest LBMD (1.45 g/cm2) amongst non-athletes. LBMD was also 0.12 g/cm2 higher in ff runners compared to ff non-athletes, whereas FF and Ff runners had 0.09 g/cm2 higher LBMD compared to their genotype-matched controls. No other interactions or variants, individually or collectively as part of a TGS, were associated with BMD (P≥0.11). CONCLUSION:High-level female runners possess higher LBMD but not TBMD in comparison with non-athletes whereas male runners possess both higher TBMD and LBMD than non-athletes. Consistent with prior literature, we observed higher BMD in VDR rs2228570 FF genotype in non-athletes, which may be due to increased biological activity associated with the F variant. However, our preliminary data suggest that the ff genotype may be associated with enhanced LBMD in male runners via a gene-environment interaction.Peer reviewedFinal Published versio

Anthropometric and Physiological Characteristics of Elite Male Rugby Athletes

This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both Rugby Union (RU) and Rugby League (RL). Anthropometric characteristics such as height and mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ~111 kg, backs ~93 kg; RL forwards ~103 kg, backs ~90 kg) with lowest % body fat (RU forwards ~15%, backs ~12%; RL forwards ~14%, backs ~11%), they have most fat-free mass and are strongest (Back squat: RU forwards ~176 kg, backs ~157 kg; RL forwards ~188 kg, backs ~ 168 kg; Bench press: RU forwards ~131 kg, backs ~118 kg; RL forwards ~122 kg, backs ~113 kg) and fastest (10 m: RU forwards ~1.87 s, backs ~1.77 s; 10 m RL forwards ~1.9 s, backs ~1.83 s). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power and strength characteristics are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels and are therefore important determinants of elite status in rugby.Published versio

An Investigation of High Frequency Motions in the Tropical Tropopause Layer near Convection

Indirect evidence indicates a role for vertical mixing in the Tropical Tropopause Layer (TTL). In the past 20 years, high altitude NASA aircraft such as the ER-2, WB-57, and GLobal Hawk have been making 20hz measurements of vertical velocity and other meteorological parameters in the Upper Tropospere-Lower Stratosphere region, many in the tropics, most recently in connection with the Airborne Tropical TRopopause EXperiment (ATTREX). In the stable environment of the UTLS, high frequency activity occurs in bursts, presumably in connection with nearby convection or strong vertical shear associated with larger scale gravity waves. This paper examines tropical high frequency aircraft data to obtain some basic information about the distribution and character of high frequency activity in vertical velocity in the TTL. In particular, we focus on relating the high frequency activity to nearby tropical convection