PRADOC: A Multicenter Randomized Controlled Trial to Assess the Efficiency of PRADO-IC, a Nationwide Pragmatic Transition Care Management Plan for Hospitalized Patients With Heart Failure in France.

BACKGROUND: The PRADO-IC (Programme de Retour à Domicile après une Insuffisance Cardiaque) is a transition care program designed to improve the coordination of care between hospital and home that was generalized in France in 2014. The PRADO-IC consists of an administrative assistant who visits patients during hospitalization to schedule follow-up visits. The aim of the present study was to evaluate the PRADO-IC program based on the hypotheses provided by health authorities. METHODS AND RESULTS: The PRADOC study is a multicenter, controlled, randomized, open-label, mixed-method trial of the transition program PRADO-IC versus usual management in patients hospitalized with heart failure (standard of care group; NCT03396081). A total of 404 patients were recruited between April 2018 and May 2021. The mean patient age was 75 years (±12 years) in both groups. The 2 groups were well balanced regarding severity indices. At discharge, patients homogeneously received the recommended drugs. There was no difference between groups regarding hospitalizations for acute heart failure at 1 year, with 24.60% in the standard of care group and 25.40% in the PRADO-IC group during the year following the index hospitalization (hazard ratio, 1.04 [95% CI, 0.69-1.56]; P=0.85) or cardiovascular mortality (hazard ratio, 0.67 [95% CI, 0.34-1.31]; P=0.24). CONCLUSIONS: The PRADO-IC has not significantly improved clinical outcomes, though a trend toward reduced cardiovascular mortality is evident. These results will help in understanding how transitional care programs remain to be integrated in pathways of current patients, including telemonitoring, and to better tailor individualized approaches. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT03396081.

Perceptions and satisfaction of patients with chronic heart failure when using a remote monitoring web application named Satelia® Cardio.

INTRODUCTION: The use of telehealth, such as remote patient monitoring (RPM), for chronic heart failure (CHF) impacts patient pathways. Patient-centricity in chronic disease management is valuable. Even though RPM is recommended in practice, the evaluation of patient satisfaction has been limited to date. The objective of this study was to assess the perceptions and satisfaction of patients with CHF when using RPM. METHODS: A voluntary declarative survey was conducted with users of Satelia® Cardio, an RPM web application which was included in an experimental model program in France funded by the ETAPES program initiative sponsored by the French Ministry of Health. Monitoring was based on patient-reported outcomes (seven questions on symptoms, one question on weight) which were answered online (digitally literate patients) or by phone with a nurse (patients with poor digital literacy). The survey included questions on perceived usefulness, ease of use and impact on quality of life (QoL). RESULTS: Overall, 87% of the 825 patients were satisfied with having their CHF digitally monitored. Patients found that the application was easy to use (94%), problem free (95%), provided well-timed notifications (98%), easily accessible (96.5%), understandable (89%), and did not require an unreasonable amount of time to answer questions (99%). Most patients felt that RPM helped physicians provide better care during their follow-ups (70%, mean score: 7.98/10) and 45% of the digitally literate patients indicated an improved QoL. CONCLUSION: Poor digitally literate patients may need human-based or assisted RPM. Patients monitored daily for CHF through RPM expressed strong satisfaction and acceptance.

PRADOC: a trial on the efficiency of a transition care management plan for hospitalized patients with heart failure in France.

AIMS: Transition care programmes are designed to improve coordination of care between hospital and home. For heart failure patients, meta-analyses show a high efficacy but with moderate evidence level. Moreover, difficulties for implementation of such programmes limit their extrapolation. METHODS AND RESULTS: We designed a mixed-method study to assess the implementation of the PRADO-IC, a nationwide transition programme that aims to be offered to every patient with heart failure in France. This programme consists essentially in an administrative assistance to schedule follow-up visits and in a nurse follow-up during 2 to 6 months and aims to reduce the annual heart failure readmission rate by 30%. This study assessed three quantitative aims: the cost to avoid a readmission for heart failure within 1 year (primary aim, intended sample size 404 patients), clinical care pathways, and system economic outcomes; and two qualitative aims: perceived problems and benefits of the PRADO-IC. All analyses will be gathered at the end of study for a joint interpretation. Strengths of this study design are the randomized controlled design, the population included in six centres with low motivation bias, the primary efficiency analysis, the secondary efficacy analyses on care pathway and clinical outcomes, and the joint qualitative analysis. Limits are the heterogeneity of centres and of intervention in a control group and parallel development of other new therapeutic interventions in this field. CONCLUSIONS: The results of this study may help decision-makers to support an administratively managed transition programme.

Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modulation of protein kinase A.

Peroxiredoxins are H2O2 scavenging enzymes that also carry out H2O2 signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2 and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2 and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modification of the conserved Cys243 inhibits the phosphorylation of a conserved Thr241 in the kinase activation loop and enzyme activity, and preventing Thr241 phosphorylation can overcome the H2O2 sensitivity of Tsa1-deficient cells. Results support a model of aging where nutrient signaling pathways constitute hubs integrating information from multiple aging-related conduits, including a peroxiredoxin-dependent response to H2O2.

Telemonitoring versus standard care in heart failure: a randomised multicentre trial.

AIMS: The aim was to assess the effect of a telemonitoring programme vs. standard care (SC) in preventing all-cause deaths or unplanned hospitalisations in heart failure (HF) at 18 months. METHODS AND RESULTS: OSICAT was a randomised, multicentre, open-label French study in 937 patients hospitalised for acute HF ≤12 months before inclusion. Patients were randomised to telemonitoring (daily body weight measurement, daily recording of HF symptoms, and personalised education) (n = 482) or to SC (n = 455). Mean ± standard deviation number of events for the primary outcome was 1.30 ± 1.85 for telemonitoring and 1.46 ± 1.98 for SC [rate ratio 0.97, 95% confidence interval (CI) 0.77-1.23; P = 0.80]. In New York Heart Association (NYHA) class III or IV HF, median time to all-cause death or first unplanned hospitalisation was 82 days in the telemonitoring group and 67 days in the SC group (P = 0.03). After adjustment for known predictive factors, telemonitoring was associated with a 21% relative risk reduction in first unplanned hospitalisation for HF [hazard ratio (HR) 0.79, 95% CI 0.62-0.99; P = 0.044); the relative risk reduction was 29% in patients with NYHA class III or IV HF (HR 0.71, 95% CI 0.53-0.95; P = 0.02), 38% in socially isolated patients (HR 0.62, 95% CI 0.39-0.98; P = 0.043), and 37% in patients who were ≥70% adherent to body weight measurement (HR 0.63, 95% CI 0.45-0.88; P = 0.006). CONCLUSION: Telemonitoring did not result in a significantly lower rate of all-cause deaths or unplanned hospitalisations in HF patients. The pre-specified subgroup results suggest the telemonitoring approach improves clinical outcomes in selected populations but need further confirmation.

Protein Corona Composition of Silica Nanoparticles in Complex Media: Nanoparticle Size does not Matter.

Biomolecules, and particularly proteins, bind on nanoparticle (NP) surfaces to form the so-called protein corona. It is accepted that the corona drives the biological distribution and toxicity of NPs. Here, the corona composition and structure were studied using silica nanoparticles (SiNPs) of different sizes interacting with soluble yeast protein extracts. Adsorption isotherms showed that the amount of adsorbed proteins varied greatly upon NP size with large NPs having more adsorbed proteins per surface unit. The protein corona composition was studied using a large-scale label-free proteomic approach, combined with statistical and regression analyses. Most of the proteins adsorbed on the NPs were the same, regardless of the size of the NPs. To go beyond, the protein physicochemical parameters relevant for the adsorption were studied: electrostatic interactions and disordered regions are the main driving forces for the adsorption on SiNPs but polypeptide sequence length seems to be an important factor as well. This article demonstrates that curvature effects exhibited using model proteins are not determining factors for the corona composition on SiNPs, when dealing with complex biological media.

Protein-Nanoparticle Interactions: What Are the Protein-Corona Thickness and Organization?

Protein adsorption on a surface is generally evaluated in terms of the evolution of the proteins' structures and functions. However, when the surface is that of a nanoparticle, the protein corona formed around it possesses a particular supramolecular structure that gives a "biological identity" to the new object. Little is known about the actual shape of the protein corona. Here, the protein corona formed by the adsorption of model proteins (myoglobin and hemoglobin) on silica nanoparticles was studied. Small-angle neutron scattering and oxygenation studies were combined to assess both the structural and functional impacts of the adsorption on proteins. Large differences in the oxygenation properties could be found while no significant global shape changes were seen after adsorption. Moreover, the structural study showed that the adsorbed proteins form an organized yet discontinuous monolayer around the nanoparticles.

Determination of good pharmacovigilance reporting practices in Quebec hospital pharmacies using a modified Delphi method.

PURPOSE: Many published guidelines are available for health care providers describing the best way to manage patient's adverse drug reactions (ADRs). However, there is a lack of guidance on the best way to promote and manage ADR reporting within hospitals. The goal of this study was to develop good pharmacovigilance reporting practices (GPRPs). METHODS: This descriptive study used a modified Delphi method. The research team developed 41 statements, according to a modified Specific Measurable Attainable Realistic Timely (SMART) method and grouped them in six categories: organization (n = 12 statements), pharmacovigilance committee (n = 4), database (n = 5), training (n = 5), tools (n = 3), and quality (n = 12). The Delphi consultation (two online rounds, conducted in 2018) involved directors of pharmacy in Quebec hospitals. RESULTS: Of 30 directors of pharmacy invited to participate in the first round, 27 (90%) did so. Following this round, the wording of five statements was modified according to pre-established rules. Twenty-five (93%) of the original 27 participants responded during the second round. Of the initial 41 statements, 37 were selected (average score ≥ 7); the other four were eliminated. Of the 37 statements selected, 22 had a "must do" formulation, 12 had a "should do" formulation, and three had a "may do" formulation. CONCLUSION: Using a modified Delphi method, we established a set of GPRPs for hospital pharmacy based on 37 statements. To our knowledge, these are the first GPRPs published in the hospital pharmacy literature.

Importance of Post-translational Modifications in the Interaction of Proteins with Mineral Surfaces: The Case of Arginine Methylation and Silica surfaces.

Understanding the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest for both basic research and practical applications involving nanotechnology. From the list of cellular proteins with the highest affinity for silica nanoparticles, we highlighted the group of proteins containing arginine-glycine-glycine (RGG) motifs. Biochemical experiments confirmed that RGG motifs interact strongly with the silica surfaces. The affinity of these motifs is further increased when the R residue is asymmetrically, but not symmetrically, dimethylated. Molecular dynamics simulations show that the asymmetrical dimethylation generates an electrostatic asymmetry in the guanidinium group of the R residue, orientating and stabilizing it on the silica surface. The RGG motifs (methylated or not) systematically target the siloxide groups on the silica surface through an ionic interaction, immediately strengthened by hydrogen bonds with proximal silanol and siloxane groups. Given that, in vivo, RGG motifs are often asymmetrically dimethylated by specific cellular methylases, our data add support to the idea that this type of methylation is a key mechanism for cells to regulate the interaction of the RGG proteins with their cellular partners.

RNA-binding proteins are a major target of silica nanoparticles in cell extracts.

Upon contact with biological fluids, nanoparticles (NPs) are readily coated by cellular compounds, particularly proteins, which are determining factors for the localization and toxicity of NPs in the organism. Here, we improved a methodological approach to identify proteins that adsorb on silica NPs with high affinity. Using large-scale proteomics and mixtures of soluble proteins prepared either from yeast cells or from alveolar human cells, we observed that proteins with large unstructured region(s) are more prone to bind on silica NPs. These disordered regions provide flexibility to proteins, a property that promotes their adsorption. The statistical analyses also pointed to a marked overrepresentation of RNA-binding proteins (RBPs) and of translation initiation factors among the adsorbed proteins. We propose that silica surfaces, which are mainly composed of Si-O- and Si-OH groups, mimic ribose-phosphate molecules (rich in -O- and -OH) and trap the proteins able to interact with ribose-phosphate containing molecules. Finally, using an in vitro assay, we showed that the sequestration of translation initiation factors by silica NPs results in an inhibition of the in vitro translational activity. This result demonstrates that characterizing the protein corona of various NPs would be a relevant approach to predict their potential toxicological effects.

Interferences of Silica Nanoparticles in Green Fluorescent Protein Folding Processes.

We investigated the relationship between unfolded proteins, silica nanoparticles and chaperonin to determine whether unfolded proteins could stick to silica surfaces and how this process could impair heat shock protein activity. The HSP60 catalyzed green fluorescent protein (GFP) folding was used as a model system. The adsorption isotherms and adsorption kinetics of denatured GFP were measured, showing that denaturation increases GFP affinity for silica surfaces. This affinity is maintained even if the surfaces are covered by a protein corona and allows silica NPs to interfere directly with GFP folding by trapping it in its unstructured state. We determined also the adsorption isotherms of HSP60 and its chaperonin activity once adsorbed, showing that SiO2 NP can interfere also indirectly with protein folding through chaperonin trapping and inhibition. This inhibition is specifically efficient when NPs are covered first with a layer of unfolded proteins. These results highlight for the first time the antichaperonin activity of silica NPs and ask new questions about the toxicity of such misfolded proteins/nanoparticles assembly toward cells.

Adaptive aneuploidy protects against thiol peroxidase deficiency by increasing respiration via key mitochondrial proteins.

Aerobic respiration is a fundamental energy-generating process; however, there is cost associated with living in an oxygen-rich environment, because partially reduced oxygen species can damage cellular components. Organisms evolved enzymes that alleviate this damage and protect the intracellular milieu, most notably thiol peroxidases, which are abundant and conserved enzymes that mediate hydrogen peroxide signaling and act as the first line of defense against oxidants in nearly all living organisms. Deletion of all eight thiol peroxidase genes in yeast (∆8 strain) is not lethal, but results in slow growth and a high mutation rate. Here we characterized mechanisms that allow yeast cells to survive under conditions of thiol peroxidase deficiency. Two independent ∆8 strains increased mitochondrial content, altered mitochondrial distribution, and became dependent on respiration for growth but they were not hypersensitive to H2O2. In addition, both strains independently acquired a second copy of chromosome XI and increased expression of genes encoded by it. Survival of ∆8 cells was dependent on mitochondrial cytochrome-c peroxidase (CCP1) and UTH1, present on chromosome XI. Coexpression of these genes in ∆8 cells led to the elimination of the extra copy of chromosome XI and improved cell growth, whereas deletion of either gene was lethal. Thus, thiol peroxidase deficiency requires dosage compensation of CCP1 and UTH1 via chromosome XI aneuploidy, wherein these proteins support hydroperoxide removal with the reducing equivalents generated by the electron transport chain. To our knowledge, this is the first evidence of adaptive aneuploidy counteracting oxidative stress.

Prescription of cardiovascular drugs in the French ODIN cohort of heart failure patients according to age and type of chronic heart failure.

BACKGROUND: Chronic heart failure (CHF) is a frequent severe disease. Disease-management programmes, which contain a therapeutic patient education component, will play a central role in improving delivery of care and reducing mortality and hospitalizations for CHF. AIMS: In order to have an up-to-date overview of medical treatment of CHF in France implemented by hospital and clinic cardiologists especially interested in CHF and therapeutic patient education, we described the prescription of cardiovascular drugs in the large ODIN cohort of CHF patients, according to age and type of CHF. METHODS: From 2007 to 2010 (median follow-up 27.2 months), CHF patients were prospectively enrolled in a multicentre 'real-world' French cohort by centres previously trained in therapeutic patient education. Patients were grouped according to age (< 60 years, 60 to<70 years, 70 to<80 years and ≥ 80 years) and type of CHF (characterized by level of LVEF: reduced, borderline or preserved). Medical prescription was described and mortality was assessed at long-term follow-up. RESULTS: The cohort consisted of 3237 patients (67.6 years; 69.4% men). The oldest age group had the highest LVEF. Blockers of the angiotensin-aldosterone system were prescribed progressively and significantly less frequently as the population advanced in age or as LVEF was more preserved. The mean dosages of the main prescribed CHF drugs remained ≥ 50% lower than those recommended for most drugs in all age and LVEF groups. Drug prescriptions were related to aetiology of reduced or preserved CHF. A global decrease in CHF drug prescription was observed for all medication classes except calcium blockers, according to maintenance of relatively or totally preserved LVEF. Survival was related to age but not to type of CHF. CONCLUSION: In CHF, and despite management by cardiologists particularly interested in CHF and specifically trained to deliver therapeutic patient education, medical prescription differed substantially from guidelines. Age and type of CHF (reduced versus preserved) appeared to be important factors in lack of adherence to guidelines. However, only age influenced mortality; the type of CHF did not affect survival.

Glutathione is essential to preserve nuclear function and cell survival under oxidative stress.

Organisms growing in aerobic environments must cope with Reactive Oxygen Species (ROS). Although ROS damage all the cellular macromolecules, they play a central role in a range of biological processes requiring a tight control of redox homeostasis. It is achieved by antioxidant systems involving a large collection of enzymes that scavenge or degrade the ROS produced endogenously during cell growth. In addition to this enzymatic protection against ROS, cells also contain small antioxidant molecules, such as glutathione (GSH). With an intracellular concentration between 1 and 10mM, GSH is the most abundant non-protein thiol in the cell and is considered as the major redox buffer of the cell. To better characterize its essential function during oxidative stress conditions, we studied the physiological response of H2O2-treated yeast cells containing different amounts of GSH. We showed that the transcriptional response of GSH-depleted cells is severely impaired, despite an efficient nuclear accumulation of the transcription factor Yap1. Moreover, oxidative stress generates high genome instability in GSH-depleted cells, but does not activate the checkpoint kinase Rad53. Surprisingly, scarce amounts of intracellular GSH are sufficient to preserve cell viability under H2O2 treatment. In these cells, oxidative stress still causes the accumulation of oxidized proteins and the inactivation of the translational activity, but nuclear DNA and nuclear functions are protected against oxidative injury, as exemplified by low mutation frequency, moderate histone carbonylation, activation of the checkpoint kinase Rad53 and of the H2O2 transcriptional response. We conclude that the essential role of GSH is to preserve nuclear function, allowing cell survival and growth resumption after oxidative stress release. We propose that cytosolic proteins are part of a protective machinery that shields the nucleus by scavenging reactive oxygen species before they can cross the nuclear membrane.

Glutathione is essential to preserve nuclear function and cell survival under oxidative stress.

Glutathione (GSH) is considered the most important redox buffer of the cell. To better characterize its essential function during oxidative stress conditions, we studied the physiological response of H2O2-treated yeast cells containing various amounts of GSH. We showed that the transcriptional response of GSH-depleted cells is severely impaired, despite an efficient nuclear accumulation of the transcription factor Yap1. Moreover, oxidative stress generates high genome instability in GSH-depleted cells, but does not activate the checkpoint kinase Rad53. Surprisingly, scarce amounts of intracellular GSH are sufficient to preserve cell viability under H2O2 treatment. In these cells, oxidative stress still causes the accumulation of oxidized proteins and the inactivation of the translational activity, but nuclear components and activities are protected against oxidative injury. We conclude that the essential role of GSH is to preserve nuclear function, allowing cell survival and growth resumption after oxidative stress release. We propose that cytosolic proteins are part of a protective machinery that shields the nucleus by scavenging reactive oxygen species before they can cross the nuclear membrane.

Structural determinants for protein adsorption/non-adsorption to silica surface.

The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nanotechnology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine) in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many π-π interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption.

Repression of class I transcription by cadmium is mediated by the protein phosphatase 2A.

Toxic metals are part of our environment, and undue exposure to them leads to a variety of pathologies. In response, most organisms adapt their metabolism and have evolved systems to limit this toxicity and to acquire tolerance. Ribosome biosynthesis being central for protein synthesis, we analyzed in yeast the effects of a moderate concentration of cadmium (Cd(2+)) on Pol I transcription that represents >60% of the transcriptional activity of the cells. We show that Cd(2+) rapidly and drastically shuts down the expression of the 35S rRNA. Repression does not result from a poisoning of any of the components of the class I transcriptional machinery by Cd(2+), but rather involves a protein phosphatase 2A (PP2A)-dependent cellular signaling pathway that targets the formation/dissociation of the Pol I-Rrn3 complex. We also show that Pol I transcription is repressed by other toxic metals, such as Ag(+) and Hg(2+), which likewise perturb the Pol I-Rrn3 complex, but through PP2A-independent mechanisms. Taken together, our results point to a central role for the Pol I-Rrn3 complex as molecular switch for regulating Pol I transcription in response to toxic metals.

Impairing the microRNA biogenesis pathway induces proteome modifications characterized by size bias and enrichment in antioxidant proteins.

Perturbation of individual microRNAs, or of the microRNA pathway, plays a role in carcinogenesis. In certain cancer cells, inhibition of the microRNA biogenesis pathway leads to a growth arrest state (CoGAM for Colony Growth Arrest induced by Microprocessor inhibition), which can be rescued by re-expression of individual microRNAs such as miR-20a. We now report that inhibition of the microRNA biogenesis pathway induced proteome changes characterized by a size bias in differentially expressed proteins, with induction of small proteins and inhibition of large ones. This size bias was observed in cells undergoing CoGAM, as well as in CoGAM-resistant cells, and in CoGAM-sensitive cells rescued by miR-20a. In this case, GO analysis of induced proteins identified by mass spectrometry revealed a significant enrichment in proteins involved in resistance to oxidative stress. In addition, H(2) O(2) treatment of Saccharomyces cerevisiae or mammalian cells led to similarly size-biased proteome modifications. Our results point to size bias as a relevant readout of proteome modifications, in particular in conditions of stress such as inhibition of the microRNA biogenesis pathway or oxidative stress. They also suggest research avenues to study the role of the microRNA pathway in proteostasis.

Glutathione degradation is a key determinant of glutathione homeostasis.

Glutathione (GSH) has several important functions in eukaryotic cells, and its intracellular concentration is tightly controlled. Combining mathematical models and (35)S labeling, we analyzed Saccharomyces cerevisiae sulfur metabolism. This led us to the observation that GSH recycling is markedly faster than previously estimated. We set up additional in vivo assays and concluded that under standard conditions, GSH half-life is around 90 min. Sulfur starvation and growth with GSH as the sole sulfur source strongly increase GSH degradation, whereas cadmium (Cd(2+)) treatment inhibits GSH degradation. Whatever the condition tested, GSH is degraded by the cytosolic Dug complex (composed of the three subunits Dug1, Dug2, and Dug3) but not by the γ-glutamyl-transpeptidase, raising the question of the role of this enzyme. In vivo, both DUG2/3 mRNA levels and Dug activity are quickly induced by sulfur deprivation in a Met4-dependent manner. This suggests that Dug activity is mainly regulated at the transcriptional level. Finally, analysis of dug2Δ and dug3Δ mutant cells shows that GSH degradation activity strongly impacts on GSH intracellular concentration and that GSH intracellular concentration does not affect GSH synthesis rate. Altogether, our data led us to reconsider important aspects of GSH metabolism, challenging notions on GSH synthesis and GSH degradation that were considered as established.

Life span extension and H(2)O(2) resistance elicited by caloric restriction require the peroxiredoxin Tsa1 in Saccharomyces cerevisiae.

Caloric restriction (CR) extends the life span of organisms ranging from yeast to primates. Here, we show that the thiol-dependent peroxiredoxin Tsa1 and its partner sulfiredoxin, Srx1, are required for CR to extend the replicative life span of yeast cells. Tsa1 becomes hyperoxidized/inactive during aging, and CR mitigates such oxidation by elevating the levels of Srx1, which is required to reduce/reactivate hyperoxidized Tsa1. CR, by lowering cAMP-PKA activity, enhances Gcn2-dependent SRX1 translation, resulting in increased resistance to H(2)O(2) and life span extension. Moreover, an extra copy of the SRX1 gene is sufficient to extend the life span of cells grown in high glucose concentrations by 20% in a Tsa1-dependent and Sir2-independent manner. The data demonstrate that Tsa1 is required to ensure yeast longevity and that CR extends yeast life span, in part, by counteracting age-induced hyperoxidation of this peroxiredoxin.