Proofreading of pre-40S ribosome maturation by a translation initiation factor and 60S subunits

In the final steps of yeast ribosome synthesis, immature translation-incompetent pre-40S particles that contain 20S pre-rRNA are converted to the mature translation-competent subunits containing the 18S rRNA. An assay for 20S pre-rRNA cleavage in purified pre-40S particles showed that cleavage by the PIN domain endonuclease Nob1 was strongly stimulated by the GTPase activity of the cytoplasmic translation initiation factor eIF5b/Fun12. Cleavage of the 20S pre-rRNA was also inhibited in vivo and in vitro by blocking binding of Fun12 to the 25S rRNA through specific methylation of its binding site. Cleavage competent pre-40S particles stably associate with Fun12 and form 80S complexes with 60S ribosomal subunits. We propose that recruitment of 60S subunits promotes GTP-hydrolysis by Fun12, leading to structural rearrangements within the pre-40S particle that bring Nob1 and the pre-rRNA cleavage site together

Nuclear DNA Replication in Trypanosomatids:There Are No Easy Methods for Solving Difficult Problems

In trypanosomatids, etiological agents of devastating diseases, replication is robust and finely controlled to maintain genome stability and function in stressful environments. However, these parasites encode several replication protein components and complexes that show potentially variant composition compared with model eukaryotes. This review focuses on the advances made in recent years regarding the differences and peculiarities of the replication machinery in trypanosomatids, including how such divergence might affect DNA replication dynamics and the replication stress response. Comparing the DNA replication machinery and processes of parasites and their hosts may provide a foundation for the identification of targets that can be used in the development of chemotherapies to assist in the eradication of diseases caused by these pathogens

Final Pre-40S Maturation Depends on the Functional Integrity of the 60S Subunit Ribosomal Protein L3

Ribosomal protein L3 is an evolutionarily conserved protein that participates in the assembly of early pre-60S particles. We report that the rpl3[W255C] allele, which affects the affinity and function of translation elongation factors, impairs cytoplasmic maturation of 20S pre-rRNA. This was not seen for other mutations in or depletion of L3 or other 60S ribosomal proteins. Surprisingly, pre-40S particles containing 20S pre-rRNA form translation-competent 80S ribosomes, and translation inhibition partially suppresses 20S pre-rRNA accumulation. The GTP-dependent translation initiation factor Fun12 (yeast eIF5B) shows similar in vivo binding to ribosomal particles from wild-type and rpl3[W255C] cells. However, the GTPase activity of eIF5B failed to stimulate processing of 20S pre-rRNA when assayed with ribosomal particles purified from rpl3[W255C] cells. We conclude that L3 plays an important role in the function of eIF5B in stimulating 3′ end processing of 18S rRNA in the context of 80S ribosomes that have not yet engaged in translation. These findings indicate that the correct conformation of the GTPase activation region is assessed in a quality control step during maturation of cytoplasmic pre-ribosomal particles

Isolated distal deep vein thrombosis: What have we learnt from the OPTIMEV study?

International audienceThe OPTIMEV (OPTimisation de l’Interrogatoire dans l’évaluation du risque throMbo-Embolique Veineux) study has provided some important and innovative information for the management of lower extremity isolated distal deep vein thrombosis (distal DVT). Indeed, if distal deep-vein thrombosis (DVT) therapeutic management is nowadays still debated, before the OPTIMEV study, the clinical relevance of these DVT itself was questioned. Via the publication of 6 articles, between 2009 and 2022, assessing risk factors, therapeutic management, and outcomes of 933 patients with distal DVT we were able to demonstrate that: - When distal deep veins are systematically screened for suspicion of DVT, distal DVT are the most frequent clinical presentation of the venous thromboembolic disease (VTE). This is also true in case of combined oral contraceptive related VTE. - Distal DVT share the same risk factors as proximal DVT and constitute two different clinical expressions of the same disease: the VTE disease. However, the weight of these risk factors differs: distal DVT are more often associated with transient risk factors whereas proximal DVT are more associated with permanent risk factors. - Deep calf vein and muscular DVT share the same risk factors, short and long-term prognoses. - In patients without history of cancer, risk of unknown cancer is similar in patients with a first distal or proximal DVT. - After 3 years and once anticoagulation has been stopped, distal DVT recur twice less as proximal DVT and mainly as distal DVT; However, in cancer patients, prognosis of distal and proximal DVT appear similar in terms of death and VTE recurrence

Cancer Associated Thrombosis:how many lung cancer patients seen in clinical practice would be eligible to a DOAC randomized controlled trial?

Background: Based on the results of randomized clinical trials (RCT) assessing direct oral anticoagulants (DOACs) for the treatment of patients with cancer-associated thrombosis, DOACs have been proposed as alternative to low molecular weight heparin by several international guidelines. However, the proportion of patients with VTE associated with lung cancer who would not have been eligible for such trials is currently unknownMethods: In a multicenter, observational study, all patients consecutively admitted from 01/2017 to 12/2019 for an acute VTE event were retrospectively analyzed. Patients were classified according to the presence or absence of non-inclusion criteria from the CARAVAGGIO study. Death, VTE recurrence and major bleeding during a 6-month follow-up were analyzed as secondary endpointsAims: The primary aim of this study was to assess the proportion of patients with lung cancer seen in clinical practice for acute VTE but ineligible for a RCT Secondary aims were to describe patients outcomes according to eligibility statusResults: Among the 302 patients included, 59 (19.5%) had lung cancer, in whom 39 (66.1%: 95%CI [54.02, 78.18]) were ineligible for the CARAVAGGIO study. Main exclusion criteria were: brain metastases (n=18, 46%), unusual deep vein thrombosis (n=10, 25.6%), ECOG PS>2 (n=10, 25.6%), risk of bleeding (n=8, 20.5%). At 6 months, the event-free survival rate was similar among groupsConclusion: Among patients with VTE associated with lung cancer, more than a half would have not been able to participate in a trial as CARAVAGGIO. Evaluation of DOACs safety and efficacy in these specific setting needs further researc

Cancer-associated thrombosis: how many patients seen in clinical practice would be eligible to a randomized controlled trial?

11th International Conference on Thrombosis and Hemostasis Issues in Cancer (ICTHIC), Bergamo, ITALY, MAY 27-29, 2022International audienc

Proposal of the French Society of Vascular Medicine for the prevention, diagnosis and treatment of venous thromboembolic disease in outpatients with COVID-19

International audienceThe proposal is intended to help physicians treating patients with COVID-19 for the diagnosis, treatment and prevention of venous thromboembolic disease either when leaving the hospital or treated as outpatients.This document is a synthesis of opinions of a working group from the French Society of Vascular Medicine (SFMV) composed of private practice and hospital-based physicians. This proposal is based on a limited level of evidence. This proposal is likely to evolve with the knowledge of the disease