Subcellular relocalization of a trans-acting factor regulates XIAP IRES-dependent translation

Translation of the X-linked inhibitor of apoptosis (XIAP) proceeds by internal ribosome entry site (IRES)-mediated initiation, a process that is physiologically important because XIAP expression is essential for cell survival under conditions of compromised cap-dependent translation, such as cellular stress. The regulation of internal initiation requires the interaction of IRES trans-acting factors (ITAFs) with the IRES element. We used RNA-affinity chromatography to identify XIAP ITAFs and isolated the heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1). We find that hnRNP A1 interacts with XIAP IRES RNA both in vitro and in vivo and that hnRNP A1 negatively regulates XIAP IRES activity. Moreover, XIAP IRES-dependent translation is significantly reduced when hnRNP A1 accumulates in the cytoplasm. Osmotic shock, a cellular stress that causes cytoplasmic accumulation of hnRNP A1, also leads to a decrease in XIAP levels that is abrogated by knockdown of hnRNP A1 expression. These results suggest that the subcellular localization of hnRNP A1 is an important determinant of its ability to negatively regulate XIAP IRES activity, suggesting that the subcellular distribution of ITAFs plays a critical role in regulating IRES-dependent translation. Our findings demonstrate that cytoplasmic hnRNP A1 is a negative regulator of XIAP IRES-dependent translation, indicating a novel function for the cytoplasmic form of this protein.     

The effect of calcium and magnesium on the interaction between β‐lactoglobulin and carotenoids from sea buckthorn berries

β‐Lactoglobulin has been shown to interact with carotenoids from sea buckthorn berries. However, previously, no studies have taken into account the effect of calcium and magnesium on the β‐lactoglobulin–carotenoids complex. This study aims to determine the effect of calcium and magnesium on the interaction between β‐lactoglobulin and carotenoids from sea buckthorn berries extract, during heating from the perspective of deepening interaction mechanisms as prerequisites for micro‐ and nanoencapsulation. Phase diagram, intrinsic fluorescence spectra, quenching experiments and synchronous spectra were employed to acquire information regarding the conformation of protein in the presence of calcium chloride and magnesium chloride. Intrinsic fluorescence data showed that, between 25°C and 60°C, the presence of calcium chloride in the complex favoured the movement of tryptophan residues to domains located at the protein–water interface, while magnesium chloride favoured the burial of tryptophan residues. Higher temperatures generated blue shifts regardless of which salt was present, suggesting exposure of tryptophan residues to the hydrophobic core of the protein. Extrinsic fluorescence intensity of the non‐heat‐treated complex with magnesium chloride was significantly higher (P < 0.01) than of the complex with calcium chloride, suggesting that 1‐anilino‐8‐naphtalenesulphonic acid was bound to a higher proportion of the β‐lactoglobulin–carotenoids complex. Calcium chloride increased extrinsic fluorescence to a greater extent than magnesium chloride at temperatures above 70°C and was related to small structural changes induced by preheating β‐lactoglobulin.     

Predictors of survival in a cohort of patients with polymyositis and dermatomyositis: effect of corticosteroids, methotrexate and azathioprine

Introduction  

The idiopathic inflammatory myopathies are rare diseases for which data regarding the natural history, response to therapies and factors affecting mortality are needed. We performed this study to examine the effects of treatment and clinical features on survival in polymyositis and dermatomyositis patients.     

The eIF4G homolog DAP5/p97 supports the translation of select mRNAs during endoplasmic reticulum stress

DAP5/p97 is a member of the eIF4G family of translation initiation factors that has been suggested to play an important role in the translation of select messenger RNA molecules. We have shown previously that the caspase-cleaved form of DAP5/p97, termed p86, is required for the induction of the endoplasmic reticulum (ER)-stress-responsive internal ribosome entry site (IRES) of the caspase inhibitor HIAP2. We show here that expression of DAP5/p97 is enhanced during ER stress by selective recruitment of DAP5/p97 mRNA into polysomes via the DAP5/p97 IRES. Importantly, enhanced translation mediated by the DAP5/p97 IRES is dependent on DAP5/p97 itself, thus providing a positive feedback loop. In addition, we show that activation of DAP5/p97 and HIAP2 IRES during ER stress requires DAP5/p97. Significantly, the induction of DAP5/p97 during ER stress is caspase-independent, whereas the induction of HIAP2 requires proteolytic processing of DAP5/p97. Thus, DAP5/p97 is a translational activator that selectively modulates translation of specific mRNAs during conditions of cellular stress in both a caspase-dependent and caspase-independent manner.     

Science-policy interfaces for biodiversity: dynamic learning environments for successful impact

To address the pressing problems associated with biodiversity loss, changes in awareness and behaviour are required from decision makers in all sectors. Science-policy interfaces (SPIs) have the potential to play an important role, and to achieve this effectively, there is a need to understand better the ways in which existing SPIs strive for effective communication, learning and behavioural change. Using a series of test cases across the world, we assess a range of features influencing the effectiveness of SPIs through communication and argumentation processes, engagement of actors and other aspects that contribute to potential success. Our results demonstrate the importance of dynamic and iterative processes of interaction to support effective SPI work. We stress the importance of seeing SPIs as dynamic learning environments and we provide recommendations for how they can enhance success in meeting their targeted outcomes. In particular, we recommend building long-term trust, creating learning environments, fostering participation and ownership of the process and building capacity to combat silo thinking. Processes to enable these changes may include, for example, inviting and integrating feedback, extended peer review and attention to contextualising knowledge for different audiences, and time and sustained effort dedicated to trust-building and developing common languages. However there are no ‘one size fits all’ solutions, and methods must be adapted to context and participants. Creating and maintaining effective dynamic learning environments will both require and encourage changes in institutional and individual behaviours: a challenging agenda, but one with potential for positive feedbacks to maintain momentum.     

Bacterial and Fungal Diversity of Quaternary Cave Sediment Deposits

The bacterial and fungal assemblages of clastic sediments collected from two caves located in north-western Romania were investigated by assessing ITS and 16S rRNA gene diversity. Bacterial members belonging to Chloroflexi, Nitrospirae, Proteobacteria, Firmicutes, Acidobacteria, Gemmatimonadetes, and fungal members of Ascomycota were identified. Except for Bacillus sp., all bacteria were related to uncultured or unknown species and the majority (86%) of the bacterial sequences from one of the caves had no close GenBank relatives. The bacterial sequences obtained clustered with species found in extreme environments. Half of the bacterial operational taxonomic units were clustered with clones isolated from deep subsurface sediments of a radioactively contaminated site in the USA. The present study represents the first attempt to identify microorganisms in Quaternary cave sediments.

Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the supplemental file.     

Internal ribosome entry site-mediated translation of Apaf-1, but not XIAP, is regulated during UV-induced cell death

Components of the cellular translation machinery are targets of caspase-mediated cleavage during apoptosis that correlates with the inhibition of protein synthesis, which accompanies apoptosis. Paradoxically, protein synthesis is required for apoptosis to occur in many experimental settings. Previous studies showed that two proteins that regulate apoptosis by controlling caspase activity, XIAP and Apaf-1, are translated by a unique, cap-independent mechanism mediated by an internal ribosome entry site (IRES) that is used preferentially under conditions in which normal cap-dependent translation is repressed. We investigated the regulation of XIAP and Apaf-1 following UVC irradiation. We show that UVC irradiation leads to the inhibition of translation and cell death. Furthermore, IRES-mediated translation of Apaf-1, but not XIAP, is enhanced by UVC irradiation, and this increase in Apaf-1 translation correlated with cell death. The enhanced Apaf-1 IRES-mediated translation is caspase-independent but is negatively modulated by the eIF2alpha kinase protein kinase RNA-like endoplasmic reticulum kinase. These data suggest that progression of UV-induced apoptosis requires IRES-mediated translation of Apaf-1 to ensure continuous levels of Apaf-1 despite an overall suppression of protein synthesis.     

Open label study of escalating doses of oral treprostinil diethanolamine in patients with systemic sclerosis and digital ischemia: pharmacokinetics and correlation with digital perfusion

Introduction

Treprostinil diethanolamine is an innovative salt form of the prostacyclin analogue, treprostinil sodium, developed as an oral sustained release (SR) osmotic tablet. The availability of a formulation permitting convenient systemic delivery might have applicability to scleroderma vascular complications. We evaluated pharmacokinetics and perfusion in scleroderma patients with digital ischemia following escalating twice-daily doses of treprostinil diethanolamine SR.

Methods

Scleroderma patients with digital ulcers were enrolled in this dual-center, open-label, phase I pharmacokinetic study. Drug concentrations and perfusion, quantified by laser Doppler imaging, were measured over 12 hours at the 2 mg and 4 mg (or maximally tolerated) doses. Pharmacokinetic parameters were determined from individual plasma concentration versus time profiles using non-compartmental analysis methods. Digital perfusion and skin temperature were modeled as a function of log-transformed drug concentration and other covariates by performing repeated measures analyses using random effects models.

Results

Nineteen scleroderma patients (84% female, 53% limited scleroderma) received treprostinil diethanolamine SR with dose titration up to 4 mg twice daily as tolerated. Peak concentrations (mean maximum plasma concentration (C_max) = 1,176 and 2,107 pg/mL) occurred approximately 3.6 hours after dose administration, and overall exposure (under the plasma concentration-time curve from time 0 to 12 hours post dose (AUC_0-12) = 7,187 and 12,992 hr*pg/mL) was linear between the 2 mg and 4 mg doses. Perfusion and digital skin temperature were positively associated with log-transformed plasma concentration at the 4 mg dose (P = 0.015 and P = 0.013, respectively). The most frequent adverse events were similar to those seen with prostacyclin analogues.

Conclusions

Oral treprostinil diethanolamine was effectively absorbed in patients with scleroderma. Drug administration was temporally associated with improved cutaneous perfusion and temperature. Treprostinil diethanolamine may provide a new therapeutic option for Raynaud''s phenomenon and the peripheral vascular disease of scleroderma.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00848939","term_id":"NCT00848939"}}NCT00848939.

Electronic supplementary material

The online version of this article (doi:10.1186/ar4216) contains supplementary material, which is available to authorized users.     

ω-3 PUFA Rich Camelina Oil By-Products Improve the Systemic Metabolism and Spleen Cell Functions in Fattening Pigs

Camelina oil-cakes results after the extraction of oil from Camelina sativa plant. In this study, camelina oil-cakes were fed to fattening pigs for 33 days and its effect on performance, plasma biochemical analytes, pro-/anti-inflammatory mediators and antioxidant detoxifying defence in spleen was investigated in comparison with sunflower meal. 24 crossbred TOPIG pigs were randomly assigned to one of two experimental dietary treatments containing either 12% sunflower meal (treatment 1-T1), or 12.0% camelina oil-cakes, rich in polyunsaturated fatty acids ω-3 (ω-3 PUFA) (treatment 2-T2). The results showed no effect of T2 diet (camelina cakes) on feed intake, average weight gain or feed efficiency. Consumption of camelina diet resulted in a significant decrease in plasma glucose concentration (18.47%) with a trend towards also a decrease of plasma cholesterol. In spleen, T2 diet modulated cellular immune response by decreasing the protein and gene expression of pro-inflammatory markers, interleukin 1-beta (IL-1β), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin (IL-8) and cyclooxigenase 2 (COX-2) in comparison with T1 diet. By contrast, T2 diet increased (P<0.05) in spleen the mRNA expression of antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase 1 (GPx1) by 3.43, 2.47 and 1.83 fold change respectively, inducible nitric oxide synthase (iNOS) (4.60 fold), endothelial nitric oxide synthase (eNOS) (3.23 fold) and the total antioxidant level (9.02%) in plasma. Camelina diet increased also peroxisome-proliferator activated receptor gamma (PPAR-γ) mRNA and decreased that of mitogen-activated protein kinase 14 (p38α MAPK) and nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB). At this level of inclusion (12%) camelina oil-cakes appears to be a potentially alternative feed source for pig which preserves a high content of ω-3 PUFA indicating antioxidant properties by the stimulation of detoxifying enzymes expression and the suppression of spleen pro-inflammatory markers.