The Hsp40 chaperone Jjj1 is required for the nucleo-cytoplasmic recycling of preribosomal factors in Saccharomyces cerevisiae.

Ribosome biogenesis is a major conserved cellular pathway that requires both ribosomal proteins and many preribosomal factors. Most of the pre-60S factors are recycled into the nucleus; some of them shuttle between the nucleus and the cytoplasm while a few others, like Rei1, are strictly cytoplasmic and are mostly involved in the dissociation/recycling of the pre-60S shuttling factors. Here, we investigated the role of the Jjj1 Hsp40 chaperone in ribosome biogenesis. The absence of Jjj1 leads to a cold sensitive phenotype, a defect in the relative amount of the large ribosomal subunit with the appearance of halfmers, and to cytoplasmic accumulation of shuttling factors such as Arx1 and Alb1, which stay bound to the pre-60S particles. Jjj1 is, thus, a novel pre-60S factor involved in the last cytoplasmic steps of the large ribosomal subunit biogenesis. We report the biochemical association of Jjj1 and Rei1 to similar pre-60S complexes, their two-hybrid interactions, and their functional links. Altogether, these results indicate that Rei1 and Jjj1 share many common features. However, while the functions of Jjj1 and Rei1 partially overlap, we could distinguish specific role of the two proteins in Arx1/Alb1 and Tif6 recycling. We propose that Jjj1 is preferentially required for the release of Arx1 and Alb1 shuttling factors from the cytoplasmic pre-60S particles while Rei1 is preferentially involved in their recycling

Ecm1 is a new pre-ribosomal factor involved in pre-60S particle export

International audienceIn eukaryotes, ribosome biogenesis is a highly conserved process that starts in the nucleus and ends in the cytoplasm. In actively growing yeast cells, it is estimated that each nuclear pore complex (NPC) contributes to the export of about 25 pre-ribosomal particles per minute. Such an extremely active process requires several redundant export receptors for the pre-60S particles. Here, we report the identification of a novel pre-60S factor, Ecm1, which partially acts like Arx1 and becomes essential when the NPC function is affected. Ecm1 depletion, combined with the deletion of NPC components led to pre-60S retention in the nucleus. Functional links that we identified between Ecm1, 60S biogenesis, pre-60S export, and the NPC were correlated with physical interactions of Ecm1 with pre-60S particles and nucleoporins. These results support that Ecm1 is an additional factor involved in pre-60S export. While Ecm1 and Arx1 have redundant functions, overproduction of either one could not complement the absence of the other, whereas overproduction of Mex67 was able to partially restore the growth defect resulting from the absence of Ecm1 or Arx1. These data highlight the involvement of many factors acting together to export pre-60S particles

Alveolar type II cells isolated from pulmonary adenocarcinoma: a model for JSRV expression in vitro

1044-1549 (Print)Journal ArticleInternational audienceOvine pulmonary adenocarcinoma (OPA) is a naturally occurring cancer in sheep, with clinical, radiologic, and histopathologic features similar to that of human pneumonic-type bronchioloalveolar carcinoma. JSRV (Jaagsiekte Sheep RetroVirus) is the etiologic agent of this contagious lung cancer in sheep. Cells involved in the tumor derive from alveolar type II cells and Clara cells, epithelial cells of the distal respiratory tract. These cells are the major site for viral expression in JSRV-infected animals. Recent studies clearly described the oncogenic properties of the JSRV envelope protein both in vitro and in vivo. Interestingly, the cellular pathways involved in the transformation process seem to be dependent of the origin and type of the cell used. In order to investigate the specific interactions between JSRV and alveolar type II cells, we developed an in vitro experimental model in which lung epithelial cells were isolated from OPA and control lungs. Cells in culture expressed alveolar type II cell specific markers such as surfactant protein (SP)-A, SP-C, and a high alkaline phosphatase activity. Alveolar Type II cells derived from tumoral lungs showed a proliferative advantage and expressed the JSRV virus. The reverse transcriptase activity decreased over passages in monolayer culture conditions, but was efficiently maintained in three-dimensional culture conditions. We thus report on the first in vitro system whereby alveolar type II cells from OPA were efficiently maintained in culture and stably expressed JSRV. This novel experimental model will set up the stage for elucidating lung epithelial transformation in the JSRV-induced tumor

Transformation mechanisms of type II pneumocytes in a virally-induced lung cancer

National audienc

Evaluation of genome and base editing tools in maize protoplasts

International audienceIntroduction Despite its rapid worldwide adoption as an efficient mutagenesis tool, plant genome editing remains a labor-intensive process requiring often several months of in vitro culture to obtain mutant plantlets. To avoid a waste in time and money and to test, in only a few days, the efficiency of molecular constructs or novel Cas9 variants (clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9) prior to stable transformation, rapid analysis tools are helpful. Methods To this end, a streamlined maize protoplast system for transient expression of CRISPR/Cas9 tools coupled to NGS (next generation sequencing) analysis and a novel bioinformatics pipeline was established. Results and discussion Mutation types found with high frequency in maize leaf protoplasts had a trend to be the ones observed after stable transformation of immature maize embryos. The protoplast system also allowed to conclude that modifications of the sgRNA (single guide RNA) scaffold leave little room for improvement, that relaxed PAM (protospacer adjacent motif) sites increase the choice of target sites for genome editing, albeit with decreased frequency, and that efficient base editing in maize could be achieved for certain but not all target sites. Phenotypic analysis of base edited mutant maize plants demonstrated that the introduction of a stop codon but not the mutation of a serine predicted to be phosphorylated in the bHLH (basic helix loop helix) transcription factor ZmICEa (INDUCER OF CBF EXPRESSIONa) caused abnormal stomata, pale leaves and eventual plant death two months after sowing

Monitoring, reporting and verifying emissions in the climate economy

The monitoring, reporting and verification (MRV) of greenhouse-gas emissions is the cornerstone of carbon pricing and management mechanisms. Here we consider peer-reviewed articles and ‘grey literature’ related to existing MRV requirements and their costs. A substantial part of the literature is the regulatory texts of the 15 most important carbon pricing and management mechanisms currently implemented. Based on a comparison of key criteria such as the scope, cost, uncertainty and flexibility of procedures, we conclude that conventional wisdom on MRV is not often promoted in existing carbon pricing mechanisms. Quantification of emissions uncertainty and incentives to reduce this uncertainty are usually only partially applied, if at all. Further, the time and resources spent on small sources of emissions would be expected to be limited. Although provisions aiming at an effort proportionate to the amount of emissions at stake — ‘materiality’ — are widespread, they are largely outweighed by economies of scale: in all schemes, MRV costs per tonne are primarily driven by the size of the source

Synthesis

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Design, Synthesis, and Evaluation of a Novel Series of Indole Sulfonamide Peroxisome Proliferator Activated Receptor (PPAR) α/γ/δ Triple Activators: Discovery of Lanifibranor, a New Antifibrotic Clinical Candidate

Here, we describe the identification and synthesis of novel indole sulfonamide derivatives that activate the three peroxisome proliferator activated receptor (PPAR) isoforms. Starting with a PPARα activator, compound <b>4</b>, identified during a high throughput screening (HTS) of our proprietary screening library, a systematic optimization led to the discovery of lanifibranor (IVA337) <b>5</b>, a moderately potent and well balanced pan PPAR agonist with an excellent safety profile. In vitro and in vivo, compound <b>5</b> demonstrated strong activity in models that are relevant to nonalcoholic steatohepatitis (NASH) pathophysiology suggesting therapeutic potential for NASH patients