Protein import in mitochondria biogenesis: Guided by targeting signals and sustained by dedicated chaperones

Mitochondria have a central role in cellular metabolism; they are responsible for the biosynthesis of amino acids, lipids, iron–sulphur clusters and regulate apoptosis. About 99% of mitochondrial proteins are encoded by nuclear genes, so the biogenesis of mitochondria heavily depends on protein import pathways into the organelle. An intricate system of well-studied import machinery facilitates the import of mitochondrial proteins. In addition, folding of the newly synthesized proteins takes place in a busy environment. A system of folding helper proteins, molecular chaperones and co-chaperones, are present to maintain proper conformation and thus avoid protein aggregation and premature damage. The components of the import machinery are well characterised, but the targeting signals and how they are recognised and decoded remains in some cases unclear. Here we provide some detail on the types of targeting signals involved in the protein import process. Furthermore, we discuss the very elaborate chaperone systems of the intermembrane space that are needed to overcome the particular challenges for the folding process in this compartment. The mechanisms that sustain productive folding in the face of aggregation and damage in mitochondria are critical components of the stress response and play an important role in cell homeostasis

The discrete roles of individual FOXO transcription factor family members in B-cell malignancies

Forkhead box (FOX) class O (FOXO) proteins are a dynamic family of transcription factors composed of four family members: FOXO1, FOXO3, FOXO4 and FOXO6. As context-dependent transcriptional activators and repressors, the FOXO family regulates diverse cellular processes including cell cycle arrest, apoptosis, metabolism, longevity and cell fate determination. A central pathway responsible for negative regulation of FOXO activity is the phosphatidylinositol-3-kinase (PI3K)-AKT signalling pathway, enabling cell survival and proliferation. FOXO family members can be further regulated by distinct kinases, both positively (e.g., JNK, AMPK) and negatively (e.g., ERK-MAPK, CDK2), with additional post-translational modifications further impacting on FOXO activity. Evidence has suggested that FOXOs behave as ‘bona fide’ tumour suppressors, through transcriptional programmes regulating several cellular behaviours including cell cycle arrest and apoptosis. However, an alternative paradigm has emerged which indicates that FOXOs operate as mediators of cellular homeostasis and/or resistance in both ‘normal’ and pathophysiological scenarios. Distinct FOXO family members fulfil discrete roles during normal B cell maturation and function, and it is now clear that FOXOs are aberrantly expressed and mutated in discrete B-cell malignancies. While active FOXO function is generally associated with disease suppression in chronic lymphocytic leukemia for example, FOXO expression is associated with disease progression in diffuse large B cell lymphoma, an observation also seen in other cancers. The opposing functions of the FOXO family drives the debate about the circumstances in which FOXOs favour or hinder disease progression, and whether targeting FOXO-mediated processes would be effective in the treatment of B-cell malignancies. Here, we discuss the disparate roles of FOXO family members in B lineage cells, the regulatory events that influence FOXO function focusing mainly on post-translational modifications, and consider the potential for future development of therapies that target FOXO activity

Interaction between socioeconomic deprivation and likelihood of pre‐emptive transplantation: influence of competing risks and referral characteristics – a retrospective study

Socioeconomic deprivation (SED) influences likelihood of pre‐emptive kidney transplantation (PET), but the mechanisms behind this are unclear. We explored the relationships between SED and patient characteristics at referral, which might explain this discrepancy. A retrospective cohort study was performed. SED was measured by Scottish Index of Multiple Deprivation (SIMD). Logistic regression evaluated predictors of PET. A competing risks survival analysis evaluated the interaction between SED and progression to end‐stage kidney disease (ESKD) and death. Of 7765 patients with follow‐up of 5.69 ± 6.52 years, 1298 developed ESKD requiring RRT; 113 received PET, 64 of which were from live donors. Patients receiving PET were “less deprived” with higher SIMD (5 ± 7 vs. 4 ± 5; P = 0.003). This appeared independent of overall comorbidity burden. SED was associated with a higher risk of death but not ESKD. Higher SIMD decile was associated with a higher likelihood of PET (OR 1.14, 95% CI 1.06, 1.23); the presence of diabetes and malignancy also reduced PET. SED was associated with reduced likelihood of PET after adjustment for baseline comorbidity, and this was not explained by risk of death or faster progression to ESKD. Education and outreach into transplantation should be augmented in areas with higher deprivation

Participant characteristics and exclusion from trials: a meta-analysis of individual participant-level data from phase 3/4 industry-funded trials in chronic medical conditions

Objectives Trials often do not represent their target populations, threatening external validity. The aim was to assess whether age, sex, comorbidity count and/or race/ethnicity are associated with likelihood of screen failure (i.e., failure to be enrolled in the trial for any reason) among potential trial participants.Design Bayesian meta-analysis of individual participant-level data (IPD).SettingIndustry-funded phase 3/4 trials in chronic medical conditions. Participants were identified as “enrolled” or “screen failure” using trial IPD.Participants Data were available for 52 trials involving 72,178 screened individuals of whom 24,733 (34%) failed screening.Main outcome measures For each trial, logistic regression models were constructed to assess likelihood of screen failure in people who had been invited to screening, regressed on age (per 10-year increment), sex (male versus female), comorbidity count (per one additional comorbidity) and race/ethnicity. Trial-level analyses were combined in Bayesian hierarchical models with pooling across condition.ResultsIn age- and sex-adjusted models across all trials, neither age nor sex was associated with increased odds of screen failure, though weak associations were detected after additionally adjusting for comorbidity (age, per 10-year increment: odds ratio [OR] 1.02; 95% credibility interval [CI] 1.01 to 1.04 and male sex: OR 0.95; 95% CI 0.91 to 1.00). Comorbidity count was weakly associated with screen failure, but in an unexpected direction (OR 0.97 per additional comorbidity, 95% CI 0.94 to 1.00, adjusted for age and sex). Those who self-reported as Black were slightly more likely to fail screening (OR 1.04; 95% CI 0.99 to 1.09); an effect which persisted after adjustment for age, sex and comorbidity count (OR 1.05; 95% CI 0.98 to 1.12). The between-trial heterogeneity was generally low, but there was evidence of heterogeneity by sex across conditions (variation in odds ratios on log-scale of 0.01-0.13).Conclusions Though the conclusions are limited by uncertainty about the completeness or accuracy of data collection among non-randomised participants, we identified mostly weak associations between age, sex, comorbidity count and Black race/ethnicity and increased likelihood of screen failure. Proportionate increases in screening these underserved populations may improve representation in trials. Trial registration Relevant trials in chronic medical conditions were identified according to pre-specified criteria (PROSPERO CRD42018048202) then analysed according to availability of IPD. <br/

Proton pump inhibitor use and progression to major adverse renal events: a competing risk analysis

Background: Proton pump inhibitors (PPIs) are associated with acute tubulointerstitial nephritis and there are reports associating their use with the development of chronic kidney disease (CKD). Aim: To determine if PPI use is associated with major adverse renal events (MARE) in patients with CKD. Design: Observational cohort study comprising patients with CKD attending secondary care renal clinics from 1 January 2006 until 31 December 2016. Methods: We collated baseline clinical, socio-demographic and biochemical data at start of PPI (PPI group) or study inception (control group). MARE was considered a composite of doubling of creatinine or end-stage renal disease. Association between PPI exposure and progression to MARE was assessed by cause-specific hazards competing risk survival analysis. Results: There were 3824 patients with CKD included in the analyses of whom 1195 were prescribed a PPI. The PPI group was younger (64.8 vs. 67.0 years, P &lt; 0.001), with lower estimated glomerular filtration rate (eGFR) (30 vs. 35 ml/min, P &lt; 0.001) and more proteinuria (64 vs. 48 mg/mmol, P &lt; 0.001). PPI use was associated with progression to MARE on multivariable adjustment (hazard ratio 1.13 [95% confidence interval 1.02–1.25], P = 0.021). Other factors significantly associated with progression to MARE were higher systolic blood pressure, lower eGFR, greater proteinuria, congestive cardiac failure and diabetes. Hypomagnesaemia was more common in the PPI group (39.5 vs. 18.9%, P &lt; 0.001). Conclusion: PPI use was associated with progression to MARE, but not death in patients with CKD after adjusting for factors known to predict declining renal function, including lower eGFR, proteinuria and comorbidities. A prospective cohort study is required to validate these findings

A Core Outcome Set for the prevention and treatment of fetal GROwth restriction: deVeloping Endpoints: the COSGROVE study.

BACKGROUND: Fetal growth restriction refers to a fetus that does not reach its genetically predetermined growth potential. It is well-recognized that growth-restricted fetuses are at increased risk of both short- and long-term adverse outcomes. Systematic evaluation of the evidence from clinical trials of fetal growth restriction is often difficult because of variation in the outcomes that are measured and reported. The development of core outcome sets for fetal growth restriction studies would enable future trials to measure similar meaningful outcomes. OBJECTIVE: The purpose of this study was to develop core outcome sets for trials of prevention or treatment of fetal growth restriction. STUDY DESIGN: This was a Delphi consensus study. A comprehensive literature review was conducted to identify outcomes that were reported in studies of prevention or treatment of fetal growth restriction. All outcomes were presented for prioritization to key stakeholders (135 healthcare providers, 68 researchers/academics, and 35 members of the public) in 3 rounds of online Delphi surveys. A priori consensus criteria were used to reach agreement on the final outcomes for inclusion in the core outcome set at a face-to-face meeting with 5 healthcare providers, 5 researchers/academics, and 6 maternity service users. RESULTS: In total, 22 outcomes were included in the final core outcome set. These outcomes were grouped under 4 domains: maternal (n=4), fetal (n=1), neonatal (n=12), and childhood (n=5). CONCLUSION: The Core Outcome Set for the prevention and treatment of fetal GROwth restriction: deVeloping Endpoints study identified a large number of potentially relevant outcomes and then reached consensus on those factors that, as a minimum, should be measured and reported in all future trials of prevention or treatment of fetal growth restriction. This will enable future trials to measure similar meaningful outcomes and to ensure that findings from different studies can be compared and combined

Clinical Study Local Anaesthetic Infiltration and Indwelling Postoperative Wound Catheters for Patients with Hip Fracture Reduce Death Rates and Length of Stay

Background. An analgesic enhanced recovery (ER) protocol for patients with a hip fracture was introduced. It was hypothesised that the ER would reduce pain, length of stay and improve clinical outcomes. The protocol used intraoperative infiltration of levobupivacaine followed by ongoing wound infusions. Methods. Consecutive patients admitted to two hospitals were eligible for the ER protocol. Numerical Reporting Scale pain scores (0-10) were recorded alongside opiate requirements. 434 patients in the ER group (316 full ER, 90 partial ER, and 28 no ER) were compared to a control group (CG) of 100 consecutive patients managed with traditional opiate analgesia. Results. Mean opiate requirement was 49.2 mg (CG) versus 32.5 mg (ER). Pain scores were significantly reduced in the full ER group, &lt; 0.0001. Direct discharge home and mean acute inpatient stay were significantly reduced ( = 0.0031 and &lt; 0.0001, resp.). 30-day mortality was 15% (CG) versus 5.5% (ER), = 0.0024. Conclusions. This analgesic ER protocol for patients with a hip fracture was safe and effective and was associated with reduced inpatient stay and mortality

Outcomes in ANCA-Associated Vasculitis in Scotland: Validation of the Renal Risk Score in a Complete National Cohort

INTRODUCTION: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) causes autoimmune-mediated inflammation of small blood vessels in multiple organs, including the kidneys. The ability to accurately predict kidney outcomes would enable a more personalized therapeutic approach. METHODS: We used our national renal biopsy registry to validate the ability of ANCA Renal Risk Score (ARRS) to predict end-stage kidney disease (ESKD) for individual patients. This score uses histopathological and biochemical data to stratify patients as high, medium, or low risk for developing ESKD. RESULTS: A total of 288 patients were eligible for inclusion in the study (low risk CONCLUSION: The ARRS better discriminates risk of ESKD in AAV and offers clinicians more prognostic information than the use of standard biochemical and clinical measures alone. This is the first time the ARRS has been validated in a national cohort. The proportion of patients with high-risk scores is lower in our cohort compared to others and should be noted as a limitation of this study

mTORC1-selective activation of translation elongation promotes disease progression in chronic lymphocytic leukemia

Targeted deletion of Raptor, a component of mechanistic target of rapamycin complex 1 (mTORC1), reveals an essential role for mTORC1 in initiation/maintenance of leukemia in a CLL model, resulting from a failure for haemopoietic stem/progenitor cells (HSPCs) to commit to the B cell lineage. Induction of Raptor-deficiency in NSG mice transplanted with Mx1-Raptor CLL progenitor cells (PKCα-KR-transduced HSPCs) after disease establishment revealed a reduction in CLL-like disease load and a significant increase in survival in the mice. Interestingly in an aggressive CLL-like disease model, rapamycin treatment reduced disease burden more effectively than AZD2014 (dual mTORC1/2 inhibitor), indicating a skew towards mTORC1 sensitivity with more aggressive disease. Rapamycin, but not ibrutinib, efficiently targeted the eEF2/eEF2K translation elongation regulatory axis, downstream of mTORC1, resulting in eEF2 inactivation through induction of eEF2T56 phosphorylation. mTOR inhibitor treatment of primary patient CLL cells halted proliferation, at least in part through modulation of eEF2K/eEF2 phosphorylation and expression, reduced protein synthesis and inhibited expression of MCL1, Cyclin A and Cyclin D2. Our studies highlight the importance of translation elongation as a driver of disease progression and identify inactivation of eEF2 activity as a novel therapeutic target for blocking CLL progression

Vitamin K supplementation to improve vascular stiffness in CKD:The K4Kidneys randomized controlled trial

BACKGROUND:Vascular calcification, a risk factor for cardiovascular disease, is common among patients with CKD and is an independent contributor to increased vascular stiffness and vascular risk in this patient group. Vitamin K is a cofactor for proteins involved in prevention of vascular calcification. Whether or not vitamin K supplementation could improve arterial stiffness in patients with CKD is unknown. METHODS:To determine if vitamin K supplementation might improve arterial stiffness in patients in CKD, we conducted a parallel-group, double-blind, randomized trial in participants aged 18 or older with CKD stage 3b or 4 (eGFR 15-45 ml/min per 1.73 m2). We randomly assigned participants to receive 400 μg oral vitamin K2 or matching placebo once daily for a year. The primary outcome was the adjusted between-group difference in carotid-femoral pulse wave velocity at 12 months. Secondary outcomes included augmentation index, abdominal aortic calcification, BP, physical function, and blood markers of mineral metabolism and vascular health. We also updated a recently published meta-analysis of trials to include the findings of this study. RESULTS:We included 159 randomized participants in the modified intention-to-treat analysis, with 80 allocated to receive vitamin K and 79 to receive placebo. Mean age was 66 years, 62 (39%) were female, and 87 (55%) had CKD stage 4. We found no differences in pulse wave velocity at 12 months, augmentation index at 12 months, BP, B-type natriuretic peptide, or physical function. The updated meta-analysis showed no effect of vitamin K supplementation on vascular stiffness or vascular calcification measures. CONCLUSIONS:Vitamin K2 supplementation did not improve vascular stiffness or other measures of vascular health in this trial involving individuals with CKD. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER:Vitamin K therapy to improve vascular health in patients with chronic kidney disease, ISRCTN21444964 (www.isrctn.com)