UMR3348 – Intégrité du génome, ARN et cancer

Publications de l’unité

Année de publication : 2018

Michaël Cerezo, Ramdane Guemiri, Sabine Druillennec, Isabelle Girault, Hélène Malka-Mahieu, Shensi Shen, Delphine Allard, Sylvain Martineau, Caroline Welsch, Sandrine Agoussi, Charlène Estrada, Julien Adam, Cristina Libenciuc, Emilie Routier, Séverine Roy, Laurent Désaubry, Alexander M Eggermont, Nahum Sonenberg, Jean Yves Scoazec, Alain Eychène, Stéphan Vagner, Caroline Robert (2018 Oct 29)

Translational control of tumor immune escape via the eIF4F-STAT1-PD-L1 axis in melanoma.

Nature medicine : DOI : 10.1038/s41591-018-0217-1 En savoir plus
Résumé

Preventing the immune escape of tumor cells by blocking inhibitory checkpoints, such as the interaction between programmed death ligand-1 (PD-L1) and programmed death-1 (PD-1) receptor, is a powerful anticancer approach. However, many patients do not respond to checkpoint blockade. Tumor PD-L1 expression is a potential efficacy biomarker, but the complex mechanisms underlying its regulation are not completely understood. Here, we show that the eukaryotic translation initiation complex, eIF4F, which binds the 5′ cap of mRNAs, regulates the surface expression of interferon-γ-induced PD-L1 on cancer cells by regulating translation of the mRNA encoding the signal transducer and activator of transcription 1 (STAT1) transcription factor. eIF4F complex formation correlates with response to immunotherapy in human melanoma. Pharmacological inhibition of eIF4A, the RNA helicase component of eIF4F, elicits powerful antitumor immune-mediated effects via PD-L1 downregulation. Thus, eIF4A inhibitors, in development as anticancer drugs, may also act as cancer immunotherapies.

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Nirakar Basnet, Hana Nedozralova, Alvaro H Crevenna, Satish Bodakuntla, Thomas Schlichthaerle, Michael Taschner, Giovanni Cardone, Carsten Janke, Ralf Jungmann, Maria M Magiera, Christian Biertümpfel, Naoko Mizuno (2018 Oct 20)

Direct induction of microtubule branching by microtubule nucleation factor SSNA1.

Nature cell biology : 1172-1180 : DOI : 10.1038/s41556-018-0199-8 En savoir plus
Résumé

Microtubules are central elements of the eukaryotic cytoskeleton that often function as part of branched networks. Current models for branching include nucleation of new microtubules from severed microtubule seeds or from γ-tubulin recruited to the side of a pre-existing microtubule. Here, we found that microtubules can be directly remodelled into branched structures by the microtubule-remodelling factor SSNA1 (also known as NA14 or DIP13). The branching activity of SSNA1 relies on its ability to self-assemble into fibrils in a head-to-tail fashion. SSNA1 fibrils guide protofilaments of a microtubule to split apart to form daughter microtubules. We further found that SSNA1 localizes at axon branching sites and has a key role in neuronal development. SSNA1 mutants that abolish microtubule branching in vitro also fail to promote axon development and branching when overexpressed in neurons. We have, therefore, discovered a mechanism for microtubule branching and implicated its role in neuronal development.

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Marine Fanny Garrido, Nicolas Jp Martin, Matthieu Bertrand, Catherine Gaudin, Frederic Commo, Nassif El Kalaany, Nader Al Nakouzi, Ladan Fazli, Elaine Del Nery, Jacques Camonis, Franck Perez, Stéphanie Lerondel, Alain LE Pape, Martin E Gleave, Yohann Loriot, Laurent Desaubry, Stephan Vagner, Karim Fizazi, Anne Chauchereau (2018 Oct 15)

Regulation of eIF4F translation initiation complex by the peptidyl prolyl isomerase FKBP7 in taxane-resistant prostate cancer.

Clinical cancer research : an official journal of the American Association for Cancer Research : DOI : clincanres.0704.2018 En savoir plus
Résumé

Targeted therapies that use the signaling pathways involved in prostate cancer are required to overcome chemoresistance and improve treatment outcomes for men. Molecular chaperones play a key role in the regulation of protein homeostasis and are potential targets for overcoming chemoresistance.

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Anissia Ait Saada, Sarah A E Lambert, Antony M Carr (2018 Aug 25)

Preserving replication fork integrity and competence via the homologous recombination pathway.

DNA repair : DOI : S1568-7864(18)30182-4 En savoir plus
Résumé

Flaws in the DNA replication process have emerged as a leading driver of genome instability in human diseases. Alteration to replication fork progression is a defining feature of replication stress and the consequent failure to maintain fork integrity and complete genome duplication within a single round of S-phase compromises genetic integrity. This includes increased mutation rates, small and large scale genomic rearrangement and deleterious consequences for the subsequent mitosis that result in the transmission of additional DNA damage to the daughter cells. Therefore, preserving fork integrity and replication competence is an important aspect of how cells respond to replication stress and avoid genetic change. Homologous recombination is a pivotal pathway in the maintenance of genome integrity in the face of replication stress. Here we review our recent understanding of the mechanisms by which homologous recombination acts to protect, restart and repair replication forks. We discuss the dynamics of these genetically distinct functions and their contribution to faithful mitoticsegregation.

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Maria M Magiera, Puja Singh, Carsten Janke (2018 May 31)

SnapShot: Functions of Tubulin Posttranslational Modifications.

Cell : 1552-1552.e1 : DOI : 10.1016/j.cell.2018.05.032 En savoir plus
Résumé

Post-translational modification of tubulin offers a mechanism for functional diversification of microtubules and regulation in a variety of physiological contexts. This SnapShot recaps the current state of understanding of tubulin posttranslational modifications and their functions in the regulation of biological processes. To view this SnapShot, open or download the PDF.

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Maria M Magiera, Puja Singh, Sudarshan Gadadhar, Carsten Janke (2018 May 31)

Tubulin Posttranslational Modifications and Emerging Links to Human Disease.

Cell : 1323-1327 : DOI : 10.1016/j.cell.2018.05.018 En savoir plus
Résumé

Tubulin posttranslational modifications are currently emerging as important regulators of the microtubule cytoskeleton and thus have a strong potential to be implicated in a number of disorders. Here, we review the latest advances in understanding the physiological roles of tubulin modifications and their links to a variety of pathologies.

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Sandrine M Caputo, Mélanie Léone, Francesca Damiola, Asa Ehlen, Aura Carreira, Pascaline Gaidrat, Alexandra Martins, Rita D Brandão, Ana Peixoto, Ana Vega, Claude Houdayer, Capucine Delnatte, Myriam Bronner, Danièle Muller, Laurent Castera, Marine Guillaud-Bataille, Inge Søkilde, Nancy Uhrhammer, Sophie Demontety, Hélène Tubeuf, Gaïa Castelain, , Uffe Birk Jensen, Ambre Petitalot, Sophie Krieger, Cédrick Lefol, Virginie Moncoutier, Nadia Boutry-Kryza, Henriette Roed Nielsen, Olga Sinilnikova, Dominique Stoppa-Lyonnet, Amanda B Spurdle, Manuel R Teixeira, Florence Coulet, Mads Thomassen, Etienne Rouleau (2018 Apr 3)

Full in-frame exon 3 skipping of BRCA2 confers high risk of breast and/or ovarian cancer.

Oncotarget : 17334-17348 : DOI : 10.18632/oncotarget.24671 En savoir plus
Résumé

Germline pathogenic variants in the gene are associated with a cumulative high risk of breast/ovarian cancer. Several variants result in complete loss of the exon-3 at the transcript level. The pathogenicity of these variants and the functional impact of loss of exon 3 have yet to be established. As a collaboration of the COVAR clinical trial group (France), and the ENIGMA consortium for investigating breast cancer gene variants, this study evaluated 8 variants resulting in complete deletion of exon 3. Clinical information for 39 families was gathered from Portugal, France, Denmark and Sweden. Multifactorial likelihood analyses were conducted using information from 293 patients, for 7 out of the 8 variants (including 6 intronic). For all variants combined the likelihood ratio in favor of causality was 4.39*10. These results provide convincing evidence for the pathogenicity of all examined variants that lead to a total exon 3 skipping, and suggest that other variants that result in complete loss of exon 3 at the molecular level could be associated with a high risk of cancer comparable to that associated with classical pathogenic variants in or gene. In addition, our functional study shows, for the first time, that deletion of exon 3 impairs the ability of cells to survive upon Mitomycin-C treatment, supporting lack of function for the altered BRCA2 protein in these cells. Finally, this study demonstrates that any variant leading to expression of only delta-exon 3 will be associated with an increased risk of breast and ovarian cancer.

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Catharina von Nicolai, Åsa Ehlén, Juan S Martinez, Aura Carreira (2018 Apr 1)

Dissecting the Recombination Mediator Activity of BRCA2 Using Biochemical Methods.

Methods in enzymology : 479-511 : DOI : S0076-6879(17)30356-7 En savoir plus
Résumé

Homologous recombination (HR) is an essential pathway to restart stalled replication forks, repair spontaneous DNA double-strand breaks, and generate genetic diversity. Together with genetic studies in model organisms, the development of purification protocols and biochemical assays has allowed investigators to begin to understand how the complex machinery of HR functions. At the core of the HR process is the recombination enzyme RecA in bacteria or RAD51 and DMC1 in eukaryotes. The main steps of HR can be reconstituted in vitro and involve: (1) The formation of a ssDNA-RAD51 complex into a helical structure termed the nucleoprotein filament after one DNA strand has been resected at the site of the break. (2) The homologous DNA pairing with an intact copy of the damaged chromatid to form a joint molecule also called displacement loop (D-loop). (3) The exchange of DNA strands and de novo DNA synthesis to restore the damaged/lost DNA. (4) The resolution of joint molecules by nucleolytic cleavage. The human tumor suppressor BRCA2 is a mediator of HR as it actively facilitates the DNA transactions of the recombination proteins RAD51 and DMC1 in a variety of ways: It stabilizes ssDNA-RAD51/DMC1 nucleoprotein filaments. It limits the assembly of RAD51 on dsDNA. It facilitates the replacement of replication protein A by RAD51. The result of these activities is a net increase of DNA strand exchange products as observed in vitro. Here, we describe some of the biochemical assays used to dissect the mediator activities of BRCA2.

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Renaud Chabrier, Carsten Janke (2018 Mar 1)

The comeback of hand drawing in modern life sciences.

Nature reviews. Molecular cell biology : DOI : 10.1038/nrm.2017.126 En savoir plus
Résumé

Scientific manuscripts are full of images. Since the birth of the life sciences, these images were in a form of hand drawings, with great examples from da Vinci, Hooke, van Leeuwenhoek, Remak, Buffon, Bovery, Darwin, Huxley, Haeckel and Gray’s Anatomy to name a few. However, in the course of the past century, photographs and simplified schematics have gradually taken over as a way of illustrating scientific data and concepts, assuming that these are ‘accurate’ representations of the truth. Here, we argue for the importance of reviving the art of scientific drawings as a way of effectively communicating complex scientific ideas to both specialists and the general public.

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Jonathan Bond, Christine Tran Quang, Guillaume Hypolite, Mohamed Belhocine, Aurélie Bergon, Gaëlle Cordonnier, Jacques Ghysdael, Elizabeth Macintyre, Nicolas Boissel, Salvatore Spicuglia, Vahid Asnafi (2018 Mar 1)

Novel Intergenically Spliced Chimera, NFATC3-PLA2G15, Is Associated with Aggressive T-ALL Biology and Outcome.

Molecular cancer research : MCR : DOI : 10.1158/1541-7786.MCR-17-0442 En savoir plus
Résumé

Leukemias are frequently characterized by the expression of oncogenic fusion chimeras that normally arise due to chromosomal rearrangements. Intergenically spliced chimeric RNAs (ISC) are transcribed in the absence of structural genomic changes, and aberrant ISC expression is now recognized as a potential driver of cancer. To better understand these potential oncogenic drivers, high-throughput RNA sequencing was performed on T-acute lymphoblastic leukemia (T-ALL) patient specimens (n = 24), and candidate T-ALL-related ISCs were identified (n = 55; a median of 4/patient). In-depth characterization of the NFATC3-PLA2G15 chimera, which was variably expressed in primary T-ALL, was performed. Functional assessment revealed that the fusion had lower activity than wild-type NFATC3 in vitro, and T-ALLs with elevated NFATC3-PLA2G15 levels had reduced transcription of canonical NFAT pathway genes in vivo Strikingly, high expression of the NFATC3-PLA2G15 chimera correlated with aggressive disease biology in murine patient-derived T-ALL xenografts, and poor prognosis in human T-ALL patients. Mol Cancer Res; 1-6. ©2018 AACR.

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Carla G Silva, Elise Peyre, Mohit H Adhikari, Sylvia Tielens, Sebastian Tanco, Petra Van Damme, Lorenza Magno, Nathalie Krusy, Gulistan Agirman, Maria M Magiera, Nicoletta Kessaris, Brigitte Malgrange, Annie Andrieux, Carsten Janke, Laurent Nguyen (2018 Feb 22)

Cell-Intrinsic Control of Interneuron Migration Drives Cortical Morphogenesis.

Cell : 1063-1078.e19 : DOI : 10.1016/j.cell.2018.01.031 En savoir plus
Résumé

Interneurons navigate along multiple tangential paths to settle into appropriate cortical layers. They undergo a saltatory migration paced by intermittent nuclear jumps whose regulation relies on interplay between extracellular cues and genetic-encoded information. It remains unclear how cycles of pause and movement are coordinated at the molecular level. Post-translational modification of proteins contributes to cell migration regulation. The present study uncovers that carboxypeptidase 1, which promotes post-translational protein deglutamylation, controls the pausing of migrating cortical interneurons. Moreover, we demonstrate that pausing during migration attenuates movement simultaneity at the population level, thereby controlling the flow of interneurons invading the cortex. Interfering with the regulation of pausing not only affects the size of the cortical interneuron cohort but also impairs the generation of age-matched projection neurons of the upper layers.

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Carsten Janke (2018 Feb 19)

A unified reviewing format for grant applications and evaluations.

EMBO reports : 187-188 : DOI : 10.15252/embr.201745611 En savoir plus
Résumé

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Rodrigo Muñoz-Castañeda, David Díaz, Leticia Peris, Annie Andrieux, Christophe Bosc, José M Muñoz-Castañeda, Carsten Janke, José R Alonso, Marie-Jo Moutin, Eduardo Weruaga (2018 Feb 15)

Cytoskeleton stability is essential for the integrity of the cerebellum and its motor- and affective-related behaviors.

Scientific reports : 3072 : DOI : 10.1038/s41598-018-21470-2 En savoir plus
Résumé

The cerebellum plays a key role in motor tasks, but its involvement in cognition is still being considered. Although there is an association of different psychiatric and cognitive disorders with cerebellar impairments, the lack of time-course studies has hindered the understanding of the involvement of cerebellum in cognitive and non-motor functions. Such association was here studied using the Purkinje Cell Degeneration mutant mouse, a model of selective and progressive cerebellar degeneration that lacks the cytosolic carboxypeptidase 1 (CCP1). The effects of the absence of this enzyme on the cerebellum of mutant mice were analyzed both in vitro and in vivo. These analyses were carried out longitudinally (throughout both the pre-neurodegenerative and neurodegenerative stages) and different motor and non-motor tests were performed. We demonstrate that the lack of CCP1 affects microtubule dynamics and flexibility, defects that contribute to the morphological alterations of the Purkinje cells (PCs), and to progressive cerebellar breakdown. Moreover, this degeneration led not only to motor defects but also to gradual cognitive impairments, directly related to the progression of cellular damage. Our findings confirm the cerebellar implication in non-motor tasks, where the formation of the healthy, typical PCs structure is necessary for normal cognitive and affective behavior.

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Stéphanie Durrieu-Gaillard, Hélène Dumay-Odelot, Galina Boldina, Nicolas J Tourasse, Delphine Allard, Fabrice André, Françoise Macari, Armelle Choquet, Pauline Lagarde, Guillaume Drutel, Thierry Leste-Lasserre, Marion Petitet, Tom Lesluyes, Lydia Lartigue-Faustin, Jean-William Dupuy, Frédéric Chibon, Robert G Roeder, Dominique Joubert, Stéphan Vagner, Martin Teichmann (2018 Jan 22)

Regulation of RNA polymerase III transcription during transformation of human IMR90 fibroblasts with defined genetic elements.

Cell cycle (Georgetown, Tex.) : 1-11 : DOI : 10.1080/15384101.2017.1405881 En savoir plus
Résumé

RNA polymerase (Pol) III transcribes small untranslated RNAs that are essential for cellular homeostasis and growth. Its activity is regulated by inactivation of tumor suppressor proteins and overexpression of the oncogene c-MYC, but the concerted action of these tumor-promoting factors on Pol III transcription has not yet been assessed. In order to comprehensively analyse the regulation of Pol III transcription during tumorigenesis we employ a model system that relies on the expression of five genetic elements to achieve cellular transformation. Expression of these elements in six distinct transformation intermediate cell lines leads to the inactivation of TP53, RB1, and protein phosphatase 2A, as well as the activation of RAS and the protection of telomeres by TERT, thereby conducting to full tumoral transformation of IMR90 fibroblasts. Transformation is accompanied by moderately enhanced levels of a subset of Pol III-transcribed RNAs (7SK; MRP; H1). In addition, mRNA and/or protein levels of several Pol III subunits and transcription factors are upregulated, including increased protein levels of TFIIIB and TFIIIC subunits, of SNAPC1 and of Pol III subunits. Strikingly, the expression of POLR3G and of SNAPC1 is strongly enhanced during transformation in this cellular transformation model. Collectively, our data indicate that increased expression of several components of the Pol III transcription system accompanied by a 2-fold increase in steady state levels of a subset of Pol III RNAs is sufficient for sustaining tumor formation.

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Année de publication : 2017

Ana Teixeira-Silva, Anissia Ait Saada, Julien Hardy, Ismail Iraqui, Marina Charlotte Nocente, Karine Fréon, Sarah A E Lambert (2017 Dec 7)

The end-joining factor Ku acts in the end-resection of double strand break-free arrested replication forks.

Nature communications : 1982 : DOI : 10.1038/s41467-017-02144-5 En savoir plus
Résumé

Replication requires homologous recombination (HR) to stabilize and restart terminally arrested forks. HR-mediated fork processing requires single stranded DNA (ssDNA) gaps and not necessarily double strand breaks. We used genetic and molecular assays to investigate fork-resection and restart at dysfunctional, unbroken forks in Schizosaccharomyces pombe. Here, we report that fork-resection is a two-step process regulated by the non-homologous end joining factor Ku. An initial resection mediated by MRN-Ctp1 removes Ku from terminally arrested forks, generating ~110 bp sized gaps obligatory for subsequent Exo1-mediated long-range resection and replication restart. The mere lack of Ku impacts the processing of arrested forks, leading to an extensive resection, a reduced recruitment of RPA and Rad51 and a slower fork-restart process. We propose that terminally arrested forks undergo fork reversal, providing a single DNA end for Ku binding. We uncover a role for Ku in regulating end-resection of unbroken forks and in fine-tuning HR-mediated replication restart.

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