Dynamic Recognition of the mRNA Cap by Saccharomyces cerevisiae eIF4E

SummaryRecognition of the mRNA 5′ m7G(5′)ppp(5′)N cap is key to translation initiation for most eukaryotic mRNAs. The cap is bound by the eIF4F complex, consisting of a cap-binding protein (eIF4E), a “scaffold” protein (eIF4G), and an RNA helicase (eIF4A). As a central early step in initiation, regulation of eIF4F is crucial for cellular viability. Although the structure and function of eIF4E have been defined, a dynamic mechanistic picture of its activity at the molecular level in the eIF4F⋅mRNA complex is still unavailable. Here, using single-molecule fluorescence, we measured the effects of Saccharomyces cerevisiae eIF4F factors, mRNA secondary structure, and the poly(A)-binding protein Pab1p on eIF4E-mRNA binding dynamics. Our data provide an integrated picture of how eIF4G and mRNA structure modulate eIF4E-mRNA interaction, and uncover an eIF4G- and poly(A)-independent activity of poly(A)-binding protein that prolongs the eIF4E⋅mRNA complex lifetime

Neural Control of Cardiovascular Function During Exercise in Hypertension

During both static and dynamic exercise hypertensive subjects can experience robust increases in arterial pressure to such an extent that heavy exercise is often not recommended in these patients due to the dangerously high levels of blood pressure sometimes observed. Currently, the mechanisms mediating this cardiovascular dysfunction during exercise in hypertension are not fully understood. The major reflexes thought to mediate the cardiovascular responses to exercise in normotensive healthy subjects are central command, arterial baroreflex and responses to stimulation of skeletal muscle mechano-sensitive and metabo-sensitive afferents. This review will summarize our current understanding of the roles of these reflexes and their interactions in mediating the altered cardiovascular responses to exercise observed in hypertension. We conclude that much work is needed to fully understand the mechanisms mediating excessive pressor response to exercise often seen in hypertensive patients

Progression of Carotid Artery Intima-Media Thickness During 12 Years in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study

OBJECTIVE This study investigated the long-term effects of intensive diabetic treatment on the progression of atherosclerosis, measured as common carotid artery intima-media thickness (IMT). RESEARCH DESIGN AND METHODS A total of 1,116 participants (52% men) in the Epidemiology of Diabetes Interventions and Complications (EDIC) trial, a long-term follow-up of the Diabetes Control and Complications Trial (DCCT), had carotid IMT measurements at EDIC years 1, 6, and 12. Mean age was 46 years, with diabetes duration of 24.5 years at EDIC year 12. Differences in IMT progression between DCCT intensive and conventional treatment groups were examined, controlling for clinical characteristics, IMT reader, and imaging device. RESULTS Common carotid IMT progression from EDIC years 1 to 6 was 0.019 mm less in intensive than in conventional (P < 0.0001), and from years 1 to 12 was 0.014 mm less (P = 0.048); but change from years 6 to 12 was similar (intensive − conventional = 0.005 mm, P = 0.379). Mean A1C levels during DCCT and DCCT/EDIC were strongly associated with progression of IMT, explaining most of the differences in IMT progression between DCCT treatment groups. Albuminuria, older age, male sex, smoking, and higher systolic blood pressure were significant predictors of IMT progression. CONCLUSIONS Intensive treatment slowed IMT progression for 6 years after the end of DCCT but did not affect IMT progression thereafter (6–12 years). A beneficial effect of prior intensive treatment was still evident 13 years after DCCT ended. These differences were attenuated but not negated after adjusting for blood pressure. These results support the early initiation and continued maintenance of intensive diabetes management in type 1 diabetes to retard atherosclerosis

Female athletes' experiences of positive growth following deselection in sport

The purpose of this study was to explore female athletes’ experiences of positive growth following deselection from provincial sport teams. Interviews were conducted with 18 women (Mage = 22.45 years, SD = 1.38) who were deselected from provincial soccer, ice hockey, and volleyball teams as adolescents. Interpretative phenomenological analysis methodology was used. The analysis was guided by Tedeschi and Calhoun’s model of posttraumatic growth. Results showed that participants questioned their identity and ability as athletes following deselection. Growth was a gradual process that unfolded over several years, experienced through a greater appreciation of the role of sport in the participants’ lives and sport becoming a priority, an enhanced sense of personal strength, developing closer social relationships, and a recognition of new and other opportunities. These findings show that cognitive processes and social relationships are critical components in the process of positive growth

Introduction and utilization of high priced HCV medicines across Europe; implications for the future

Background: Infection with the Hepatitis C Virus (HCV) is a widespread transmittable disease with a diagnosed prevalence of 2.0%. Fortunately, it is now curable in most patients. Sales of medicines to treat HCV infection grew 2.7% per year between 2004 and 2011, enhanced by the launch of the protease inhibitors (PIs) boceprevir (BCV) and telaprevir (TVR) in addition to ribavirin and pegylated interferon (pegIFN). Costs will continue to rise with new treatments including sofosbuvir, which now include interferon free regimens. de Bruijn et al. HCV Medicines Objective: Assess the uptake of BCV and TVR across Europe from a health authority perspective to offer future guidance on dealing with new high cost medicines. Methods: Cross-sectional descriptive study of medicines to treat HCV (pegIFN, ribavirin, BCV and TVR) among European countries from 2008 to 2013. Utilization measured in defined daily doses (DDDs)/1000 patients/quarter (DIQs) and expenditure in Euros/DDD. Health authority activities to influence treatments categorized using the 4E methodology (Education, Engineering, Economics and Enforcement). Results: Similar uptake of BCV and TVR among European countries and regions, ranging from 0.5 DIQ in Denmark, Netherlands and Slovenia to 1.5 DIQ in Tayside and Catalonia in 2013. However, different utilization of the new PIs vs. ribavirin indicates differences in dual vs. triple therapy, which is down to factors including physician preference and genotypes. Reimbursed prices for BCV and TVR were comparable across countries. Conclusion: There was reasonable consistency in the utilization of BCV and TVR among European countries in comparison with other high priced medicines. This may reflect the social demand to limit the transmission of HCV. However, the situation is changing with new curative medicines for HCV genotype 1 (GT1) with potentially an appreciable budget impact. These concerns have resulted in different prices across countries, with their impact on budgets and patient outcomes monitored in the future to provide additional guidance

Networked T Cell Death following Macrophage Infection by Mycobacterium tuberculosis

<div><h3>Background</h3><p>Depletion of T cells following infection by <em>Mycobacterium tuberculosis</em> (Mtb) impairs disease resolution, and interferes with clinical test performance that relies on cell-mediated immunity. A number of mechanisms contribute to this T cell suppression, such as activation-induced death and trafficking of T cells out of the peripheral circulation and into the diseased lungs. The extent to which Mtb infection of human macrophages affects T cell viability however, is not well characterised.</p> <h3>Methodology/Principal Findings</h3><p>We found that lymphopenia (<1.5×10⁹ cells/l) was prevalent among culture-positive tuberculosis patients, and lymphocyte counts significantly improved post-therapy. We previously reported that Mtb-infected human macrophages resulted in death of infected and uninfected bystander macrophages. In the current study, we sought to examine the influence of infected human alveolar macrophages on T cells. We infected primary human alveolar macrophages (the primary host cell for Mtb) or PMA-differentiated THP-1 cells with Mtb H37Ra, then prepared cell-free supernatants. The supernatants of Mtb-infected macrophages caused dose-dependent, caspase-dependent, T cell apoptosis. This toxic effect of infected macrophage secreted factors did not require TNF-α or Fas. The supernatant cytotoxic signal(s) were heat-labile and greater than 50 kDa in molecular size. Although ESAT-6 was toxic to T cells, other Mtb-secreted factors tested did not influence T cell viability; nor did macrophage-free Mtb bacilli or broth from Mtb cultures. Furthermore, supernatants from <em>Mycobacterium bovis</em> Bacille de Calmette et Guerin (BCG)- infected macrophages also elicited T cell death suggesting that ESAT-6 itself, although cytotoxic, was not the principal mediator of T cell death in our system.</p> <h3>Conclusions</h3><p>Mtb-Infected macrophages secrete heat-labile factors that are toxic to T cells, and may contribute to the immunosuppression seen in tuberculosis as well as interfere with microbial eradication in the granuloma.</p> </div

Homeostatic proliferation generates long-lived natural killer cells that respond against viral infection

Like memory T cells, natural killer cells that undergo homeostatic expansion in mice self-renew and retain the ability to respond to subsequent viral infection

Dynamic changes in eIF4F-mRNA interactions revealed by global analyses of environmental stress responses

BACKGROUND: Translation factors eIF4E and eIF4G form eIF4F, which interacts with the messenger RNA (mRNA) 5' cap to promote ribosome recruitment and translation initiation. Variations in the association of eIF4F with individual mRNAs likely contribute to differences in translation initiation frequencies between mRNAs. As translation initiation is globally reprogrammed by environmental stresses, we were interested in determining whether eIF4F interactions with individual mRNAs are reprogrammed and how this may contribute to global environmental stress responses. RESULTS: Using a tagged-factor protein capture and RNA-sequencing (RNA-seq) approach, we have assessed how mRNA associations with eIF4E, eIF4G1 and eIF4G2 change globally in response to three defined stresses that each cause a rapid attenuation of protein synthesis: oxidative stress induced by hydrogen peroxide and nutrient stresses caused by amino acid or glucose withdrawal. We find that acute stress leads to dynamic and unexpected changes in eIF4F-mRNA interactions that are shared among each factor and across the stresses imposed. eIF4F-mRNA interactions stabilised by stress are predominantly associated with translational repression, while more actively initiating mRNAs become relatively depleted for eIF4F. Simultaneously, other mRNAs are insulated from these stress-induced changes in eIF4F association. CONCLUSION: Dynamic eIF4F-mRNA interaction changes are part of a coordinated early translational control response shared across environmental stresses. Our data are compatible with a model where multiple mRNA closed-loop complexes form with differing stability. Hence, unexpectedly, in the absence of other stabilising factors, rapid translation initiation on mRNAs correlates with less stable eIF4F interactions