166 research outputs found

    Leucyl-tRNA synthetase controls TORC1 via the EGO complex

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    The target of rapamycin complex 1 (TORC1) is an essential regulator of eukaryotic cell growth that responds to growth factors, energy levels, and amino acids. The mechanisms through which the preeminent amino acid leucine signals to the TORC1-regulatory Rag GTPases, which activate TORC1 within the yeast EGO complex (EGOC) or the structurally related mammalian Rag-Ragulator complex, remain elusive. We find that the leucyl-tRNA synthetase (LeuRS) Cdc60 interacts with the Rag GTPase Gtr1 of the EGOC in a leucine-dependent manner. This interaction is necessary and sufficient to mediate leucine signaling to TORC1 and is disrupted by the engagement of Cdc60 in editing mischarged tRNALeu. Thus, the EGOC-TORC1 signaling module samples, via the LeuRS-intrinsic editing domain, the fidelity of tRNALeu aminoacylation as a proxy for leucine availability

    The evolutionary conserved BER1 gene is involved in microtubule stability in yeast

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    In yeast, microtubules are dynamic filaments necessary for spindle and nucleus positioning, as well as for proper chromosome segregation. We identify a function for the yeast gene BER1 (Benomyl REsistant 1) in microtubule stability. BER1 belongs to an evolutionary conserved gene family whose founding member Sensitivity to Red light Reduced is involved in red-light perception and circadian rhythms in Arabidopsis. Here, we present data showing that the ber1Δ mutant is affected in microtubule stability, particularly in presence of microtubule-depolymerising drugs. The pattern of synthetic lethal interactions obtained with the ber1Δ mutant suggests that Ber1 may function in N-terminal protein acetylation. Our work thus suggests that microtubule stability might be regulated through this post-translational modification on yet-to-be determined protein

    The I-BAR protein Ivy1 is an effector of the Rab7 GTPase Ypt7 involved in vacuole membrane homeostasis

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    Membrane fusion at the vacuole depends on a conserved machinery that includes SNAREs, the Rab7 homolog Ypt7 and its effector HOPS. Here, we demonstrate that Ypt7 has an unexpected additional function by controlling membrane homeostasis and nutrient-dependent signaling on the vacuole surface. We show that Ivy1, the yeast homolog of mammalian missing-in-metastasis (MIM), is a vacuolar effector of Ypt7-GTP and interacts with the EGO/ragulator complex, an activator of the target of rapamycin kinase complex 1 (TORC1) on vacuoles. Loss of Ivy1 does not affect EGO vacuolar localization and function. In combination with the deletion of individual subunits of the V-ATPase, however, we observed reduced TORC1 activity and massive enlargement of the vacuole surface. Consistent with this, Ivy1 localizes to invaginations at the vacuole surface and on liposomes in a phosphoinositide- and Ypt7-GTP-controlled manner, which suggests a role in microautophagy. Our data, thus, reveal that Ivy1 is a novel regulator of vacuole membrane homeostasis with connections to TORC1 signaling

    Dipyridamole-thallium/sestamibi before vascular surgery: A prospective blinded study in moderate-risk patients

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    AbstractPurpose: This study assessed in a prospective, blinded fashion whether a reversible defect on dipyridamole-thallium (DTHAL)/sestamibi (DMIBI) can predict adverse cardiac events after elective vascular surgery in patients with one or more clinical risk factors. Methods: Consecutive patients with one or more clinical risk factors underwent a preoperative blinded DTHAL/DMIBI. Patients with recent congestive heart failure (CHF) or myocardial infarction (MI) or severe or unstable angina were excluded. Results: Eighty patients (78% men; mean age, 65 years) completed the study. Diabetes mellitus was the most frequent clinical risk factor (73%), followed by age older than 70 years (41%), angina (29%), Q wave on electrocardiogram (26%), history of CHF (7%), and ventricular ectopy (3%). The results of DTHAL/DMIBI were normal in 36 patients (45%); a reversible plus or minus fixed defect was demonstrated in 28 patients (36%), and a fixed defect alone was demonstrated in 15 patients (19%). Nine adverse cardiac events (11%) occurred, including three cases of CHF, and one case each of unstable angina, Q wave MI, non-Q wave MI, and cardiac arrest (successfully resuscitated). Two cardiac deaths occurred (2% overall mortality), one after a Q wave MI and one after CHF and a non-Q wave MI. The cardiac event rate was 14% for reversible defect and 9.8% without reversible defect (P =.71). The cardiac event rate was 12.5% (one of eight cases) for two or more reversible defects, versus 11.1% (eight of 72 cases) for fewer than two reversible defects (P = 1.0). The sensitivity rate of two or more areas of redistribution was 11% (95% CI, 0.3%-48%), the specificity rate was 90%, and the positive and negative predictive values were 12.5% and 89%, respectively. Conclusion: Our study demonstrated no association between reversible defects on DTHAL/DMIBI and adverse cardiac events in moderate-risk patients undergoing elective vascular surgery. (J Vasc Surg 2000;32:77-89.

    TORC1 determines Fab1 lipid kinase function at signaling endosomes and vacuoles

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    Acknowledgments: We thank Lars Langemeyer for feedback, all members from the Ungermann lab for discussions, and Kathrin Auffarth, Angela Perz, and Malika Jaquenoud for expert technical assistance. This work was supported by the DFG (UN111/10-1 to C.U.), the Canton of Fribourg (to J.D. and C.D.V.), and the Swiss National Science Foundation (310030_166474/184671 to C.D.V. and 310030_184781 and 316030_177088 to J.D.). Z.C. received support from a travel stipend of the Boehringer Ingelheim Fonds. P.C.M. received additional support from the graduate program of the Collaborative Research Center 944 (SFB 944) and Department of Biology/Chemistry Osnabrück. E.E. received a fellowship of FWO Vlaanderen, Belgium (SB-FWO 1S06419N). Author Contributions: Z.C. and P.C.M. conducted all experiments on Fab1 localization and function; R.H. conducted experiments on development and analysis of the Sch91–183 probe; R.N., Z.H., M.-P.P.-G., and J.D. did the phosphorylation assays and analyses; and E.E. and J.W. conceived and performed the initial Sch9 mapping. T.N. and C.J.S. did the lipid analysis of the mutant alleles. J.G. analyzed microcopy data with Z.C. C.D.V. and C.U. conceived the study and wrote the manuscript with support of J.W.Peer reviewedPublisher PD

    Complementary roles of wild boar and red deer to animal tuberculosis maintenance in multi-host communities

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    [EN] The contribution of wildlife species to pathogen maintenance in multi-host communities has seldom been quantified. To assess the relative contribution of the main wildlife hosts of animal tuberculosis (TB) to its maintenance, we estimated the basic reproduction number (R0) of Mycobacterium tuberculosis complex in wild boar and red deer at 29 sites in the Iberian Peninsula. Host abundance and true TB prevalence were estimated for each species at each site by sampling from distributions incorporating the uncertainty in the proportion of the population harvested each year, sensitivity, and specificity of the diagnostic methods, while excretion of mycobacteria was estimated using site-occupancy models. The distributions of these parameters were then used to estimate, at each site, the R0,wild boar (range 0.1 – 55.9, average 8.7, standard deviation 11.8), and the R0,red deer (0.1 – 18.9, 2.2, 3.9). Animal TB is maintained in epidemiological scenarios ranging from any single species acting as a maintenance host (the wild boar in 18 sites and the red deer in 5), to facultative multi-host disease (6 sites). The prevalence of TB in the red deer is likely an important driver of the epidemiology in multi-host communities. The wild boar was the main maintenance host of TB in most of the study sites and could have an epidemiological role linking the wildlife multi-host community and livestockSIThis work was supported by Fundaç˜ao para a Ciˆencia e Tecnologia [project grant EXPL/CVT-CVT/1525/2021 and fellowship SFRH/BPD/ 116596/2016 to N.S.]. FCT/MCTES for the financial support to CESAM (UIDP/50017/2020 +UIDB/50017/2020), through national fund

    Quantification of CH4 emissions from waste disposal sites near the city of Madrid using ground- and space-based observations of COCCON, TROPOMI and IASI

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    We use different methane ground- and space-based remote sensing data sets for investigating the emission strength of three waste disposal sites close to Madrid. We present a method that uses wind-assigned anomalies for deriving emission strengths from satellite data and estimating their uncertainty to 9–14 %. The emission strengths estimated from the remote sensing data sets are significantly larger than the values published in the official register.ESA support through the COCCON-PROCEEDS and COCCON-PROCEEDS II projects. In addition, this research was funded by the Ministerio de Economía y Competitividad from Spain through the INMENSE project (CGL2016-80688-P). This research has largely benefit from funds of the Deutsche Forschungsgemeinschaft (provided for the two projects MOTIV and TEDDY with IDs/290612604 and 416767181, respectively)

    Uncertainties and controversies in axillary management of patients with breast cancer

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    The aims of this Oncoplastic Breast Consortium and European Breast Cancer Research Association of Surgical Trialists initiative were to identify uncertainties and controversies in axillary management of early breast cancer and to recommend appropriate strategies to address them. By use of Delphi methods, 15 questions were prioritized by more than 250 breast surgeons, patient advocates and radiation oncologists from 60 countries. Subsequently, a global virtual consensus panel considered available data, ongoing studies and resource utilization. It agreed that research should no longer be prioritized for standardization of axillary imaging, de-escalation of axillary surgery in node-positive cancer and risk evaluation of modern surgery and radiotherapy. Instead, expert consensus recommendations for clinical practice should be based on current evidence and updated once results from ongoing studies become available. Research on de-escalation of radiotherapy and identification of the most relevant endpoints in axillary management should encompass a meta-analysis to identify knowledge gaps, followed by a Delphi process to prioritize and a consensus conference to refine recommendations for specific trial designs. Finally, treatment of residual nodal disease after surgery was recommended to be assessed in a prospective register

    Enzymatic Blockade of the Ubiquitin-Proteasome Pathway

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    Ubiquitin-dependent processes control much of cellular physiology. We show that expression of a highly active, Epstein-Barr virus-derived deubiquitylating enzyme (EBV-DUB) blocks proteasomal degradation of cytosolic and ER-derived proteins by preemptive removal of ubiquitin from proteasome substrates, a treatment less toxic than the use of proteasome inhibitors. Recognition of misfolded proteins in the ER lumen, their dislocation to the cytosol, and degradation are usually tightly coupled but can be uncoupled by the EBV-DUB: a misfolded glycoprotein that originates in the ER accumulates in association with cytosolic chaperones as a deglycosylated intermediate. Our data underscore the necessity of a DUB activity for completion of the dislocation reaction and provide a new means of inhibition of proteasomal proteolysis with reduced cytotoxicity.National Institutes of Health (U.S.)EMBO (long term Fellowship 2008-379)Boehringer Ingelheim Fond

    Oncoplastic Breast Consortium consensus conference on nipple-sparing mastectomy

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    Purpose Indications for nipple-sparing mastectomy (NSM) have broadened to include the risk reducing setting and locally advanced tumors, which resulted in a dramatic increase in the use of NSM. The Oncoplastic Breast Consortium consensus conference on NSM and immediate reconstruction was held to address a variety of questions in clinical practice and research based on published evidence and expert panel opinion. Methods The panel consisted of 44 breast surgeons from 14 countries across four continents with a background in gynecology, general or reconstructive surgery and a practice dedicated to breast cancer, as well as a patient advocate. Panelists presented evidence summaries relating to each topic for debate during the in-person consensus conference. The iterative process in question development, voting, and wording of the recommendations followed the modified Delphi methodology. Results Consensus recommendations were reached in 35, majority recommendations in 24, and no recommendations in the remaining 12 questions. The panel acknowledged the need for standardization of various aspects of NSM and immediate reconstruction. It endorsed several oncological contraindications to the preservation of the skin and nipple. Furthermore, it recommended inclusion of patients in prospective registries and routine assessment of patient-reported outcomes. Considerable heterogeneity in breast reconstruction practice became obvious during the conference. Conclusions In case of conflicting or missing evidence to guide treatment, the consensus conference revealed substantial disagreement in expert panel opinion, which, among others, supports the need for a randomized trial to evaluate the safest and most efficacious reconstruction techniques
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