UMR3348 – Intégrité du génome, ARN et cancer

Publications de l’unité

Année de publication : 2018

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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Carsten Janke, Guillaume Montagnac (2017 Dec 4)

Causes and Consequences of Microtubule Acetylation.

Current biology : CB : R1287-R1292 : DOI : S0960-9822(17)31381-7 En savoir plus
Résumé

Among the different types of cytoskeletal components, microtubules arguably accumulate the greatest diversity of post-translational modifications (PTMs). Acetylation of lysine 40 (K40) of α-tubulin has received particular attention because it is the only tubulin PTM to be found in the lumen of microtubules: most other tubulin PTMs are found at the outer surface of the microtubule. As a consequence, the enzyme catalyzing K40 acetylation needs to penetrate the narrow microtubule lumen to find its substrate. Acetylated microtubules have been considered to be stable, long-lived microtubules; however, until recently, there was little information about whether the longevity of these microtubules is the cause or the consequence of acetylation. Current advances suggest that this PTM helps the microtubule lattice to cope with mechanical stress, thus facilitating microtubule self-repair. These observations now shed new light on the structural integrity of microtubules, as well as on the mechanisms and biological functions of tubulin acetylation. Here, we discuss recent insights into how acetylation is generated in the lumen of microtubules, and how this ‘hidden’ PTM can control the properties and functions of microtubules.

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Alexis Fouquin, Josée Guirouilh-Barbat, Bernard Lopez, Janet Hall, Mounira Amor-Guéret, Vincent Pennaneach (2017 Dec 1)

PARP2 controls double-strand break repair pathway choice by limiting 53BP1 accumulation at DNA damage sites and promoting end-resection.

Nucleic acids research : DOI : 10.1093/nar/gkx881 En savoir plus
Résumé

Double strand breaks (DSBs) are one of the most toxic lesions to cells. DSB repair by the canonical non-homologous end-joining (C-EJ) pathway involves minor, if any, processing of the broken DNA-ends, whereas the initiation of DNA resection channels the broken-ends toward DNA repair pathways using various lengths of homology. Mechanisms that control the resection initiation are thus central to the regulation to the choice of DSB repair pathway. Therefore, understanding the mechanisms which regulate the initiation of DNA end-resection is of prime importance. Our findings reveal that poly(ADP-ribose) polymerase 2 (PARP2) is involved in DSBR pathway choice independently of its PAR synthesis activity. We show that PARP2 favors repair by homologous recombination (HR), single strand annealing (SSA) and alternative-end joining (A-EJ) rather than the C-EJ pathway and increases the deletion sizes at A-EJ junctions. We demonstrate that PARP2 specifically limits the accumulation of the resection barrier factor 53BP1 at DNA damage sites, allowing efficient CtIP-dependent DNA end-resection. Collectively, we have identified a new PARP2 function, independent of its PAR synthesis activity, which directs DSBs toward resection-dependent repair pathways.

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Takashi Akera, Lukáš Chmátal, Emily Trimm, Karren Yang, Chanat Aonbangkhen, David M Chenoweth, Carsten Janke, Richard M Schultz, Michael A Lampson (2017 Nov 3)

Spindle asymmetry drives non-Mendelian chromosome segregation.

Science (New York, N.Y.) : 668-672 : DOI : 10.1126/science.aan0092 En savoir plus
Résumé

Genetic elements compete for transmission through meiosis, when haploid gametes are created from a diploid parent. Selfish elements can enhance their transmission through a process known as meiotic drive. In female meiosis, selfish elements drive by preferentially attaching to the egg side of the spindle. This implies some asymmetry between the two sides of the spindle, but the molecular mechanisms underlying spindle asymmetry are unknown. Here we found that CDC42 signaling from the cell cortex regulated microtubule tyrosination to induce spindle asymmetry and that non-Mendelian segregation depended on this asymmetry. Cortical CDC42 depends on polarization directed by chromosomes, which are positioned near the cortex to allow the asymmetric cell division. Thus, selfish meiotic drivers exploit the asymmetry inherent in female meiosis to bias their transmission.

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Michelle Newman, Rym Sfaxi, Abhijit Saha, David Monchaud, Marie-Paule Teulade-Fichou, Stéphan Vagner (2017 Oct 27)

The G-Quadruplex-Specific RNA Helicase DHX36 Regulates p53 Pre-mRNA 3′-End Processing Following UV-Induced DNA Damage.

Journal of Molecular Biology : 429 : 3121-3131 : DOI : 10.1016/j.jmb.2016.11.033 En savoir plus
Résumé

Pre-mRNA 3′-end processing, the process through which almost all eukaryotic mRNAs acquire a poly(A) tail is generally inhibited during the cellular DNA damage response leading to a profound impact on the level of protein expression since unprocessed transcripts at the 3′-end will be degraded or unable to be transported to the cytoplasm. However, a compensatory mechanism involving the binding of the hnRNP H/F family of RNA binding proteins to an RNA G-quadruplex (G4) structure located in the vicinity of a polyadenylation site has previously been described to allow the transcript encoding the p53 tumour suppressor protein to be properly processed during DNA damage and to provide the cells with a way to react to DNA damage. Here we report that the DEAH (Asp-Glu-Ala-His) box RNA helicase DHX36/RHAU/G4R1, which specifically binds to and resolves parallel-stranded G4, is necessary to maintain p53 pre-mRNA 3′-end processing following UV-induced DNA damage. DHX36 binds to the p53 RNA G4, while mutation of the G4 impairs the ability of DHX36 to maintain pre-mRNA 3′-end processing. Stabilization of the p53 RNA G4 with two different G4 ligands ((PNA)DOTASQ and PhenDC3), which is expected from previous studies to prevent DHX36 from binding and unwinding G4s, also impairs p53 pre-mRNA 3′-end processing following UV. Our work identifies DHX36 as a new actor in the compensatory mechanisms that are in place to ensure that the mRNAs encoding p53 are still processed following UV.

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Martin Dutertre, Stéphan Vagner (2017 Oct 27)

DNA-Damage response RNA-Binding Proteins (DDRBPs): Perspectives from a new class of proteins and their RNA targets.

Journal of molecular biology : DOI : 10.1016/j.jmb.2016.09.019 En savoir plus
Résumé

Upon DNA damage, cells trigger an early DNA-damage response (DDR) involving DNA repair and cell cycle checkpoints, and late responses involving gene expression regulation that determine cell fate. Screens for genes involved in the DDR have found many RNA-binding proteins (RBPs), while screens for novel RBPs have identified DDR proteins. An increasing number of RBPs are involved in the early and/or late DDR. We propose to call this new class of actors of the DDR that contain an RNA-binding activity, DNA-damage response RNA-binding proteins (DDRBPs). We then discuss how DDRBPs not only contribute to gene expression regulation in the late DDR, but also to early DDR signaling, DNA repair and chromatin modifications at DNA damage sites through interactions with both long and short noncoding RNAs.

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Elias Bou Samra, Géraldine Buhagiar-Labarchède, Christelle Machon, Jérôme Guitton, Rosine Onclercq-Delic, Michael R Green, Olivier Alibert, Claude Gazin, Xavier Veaute, Mounira Amor-Guéret (2017 Sep 25)

A role for Tau protein in maintaining ribosomal DNA stability and cytidine deaminase-deficient cell survival.

Nature communications : 693 : DOI : 10.1038/s41467-017-00633-1 En savoir plus
Résumé

Cells from Bloom’s syndrome patients display genome instability due to a defective BLM and the downregulation of cytidine deaminase. Here, we use a genome-wide RNAi-synthetic lethal screen and transcriptomic profiling to identify genes enabling BLM-deficient and/or cytidine deaminase-deficient cells to tolerate constitutive DNA damage and replication stress. We found a synthetic lethal interaction between cytidine deaminase and microtubule-associated protein Tau deficiencies. Tau is overexpressed in cytidine deaminase-deficient cells, and its depletion worsens genome instability, compromising cell survival. Tau is recruited, along with upstream-binding factor, to ribosomal DNA loci. Tau downregulation decreases upstream binding factor recruitment, ribosomal RNA synthesis, ribonucleotide levels, and affects ribosomal DNA stability, leading to the formation of a new subclass of human ribosomal ultrafine anaphase bridges. We describe here Tau functions in maintaining survival of cytidine deaminase-deficient cells, and ribosomal DNA transcription and stability. Moreover, our findings for cancer tissues presenting concomitant cytidine deaminase underexpression and Tau upregulation open up new possibilities for anti-cancer treatment.Cytidine deaminase (CDA) deficiency leads to genome instability. Here the authors find a synthetic lethal interaction between CDA and the microtubule-associated protein Tau deficiencies, and report that Tau depletion affects rRNA synthesis, ribonucleotide pool balance, and rDNA stability.

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Sudarshan Gadadhar, Hala Dadi, Satish Bodakuntla, Anne Schnitzler, Ivan Bièche, Filippo Rusconi, Carsten Janke (2017 Sep 4)

Tubulin glycylation controls primary cilia length.

The Journal of cell biology : 2701-2713 : DOI : 10.1083/jcb.201612050 En savoir plus
Résumé

As essential components of the eukaryotic cytoskeleton, microtubules fulfill a variety of functions that can be temporally and spatially controlled by tubulin posttranslational modifications. Tubulin glycylation has so far been mostly found on motile cilia and flagella, where it is involved in the stabilization of the axoneme. In contrast, barely anything is known about the role of glycylation in primary cilia because of limitations in detecting this modification in these organelles. We thus developed novel glycylation-specific antibodies with which we detected glycylation in many primary cilia. Glycylation accumulates in primary cilia in a length-dependent manner, and depletion or overexpression of glycylating enzymes modulates the length of primary cilia in cultured cells. This strongly suggests that glycylation is essential for the homeostasis of primary cilia, which has important implications for human disorders related to primary cilia dysfunctions, such as ciliopathies and certain types of cancer.

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Richard Belvindrah, Kathiresan Natarajan, Preety Shabajee, Elodie Bruel-Jungerman, Jennifer Bernard, Marie Goutierre, Imane Moutkine, Xavier H Jaglin, Mythili Savariradjane, Theano Irinopoulou, Jean-Christophe Poncer, Carsten Janke, Fiona Francis (2017 Aug 7)

Mutation of the α-tubulin Tuba1a leads to straighter microtubules and perturbs neuronal migration.

The Journal of cell biology : 2443-2461 : DOI : 10.1083/jcb.201607074 En savoir plus
Résumé

Brain development involves extensive migration of neurons. Microtubules (MTs) are key cellular effectors of neuronal displacement that are assembled from α/β-tubulin heterodimers. Mutation of the α-tubulin isotype TUBA1A is associated with cortical malformations in humans. In this study, we provide detailed in vivo and in vitro analyses of Tuba1a mutants. In mice carrying a Tuba1a missense mutation (S140G), neurons accumulate, and glial cells are dispersed along the rostral migratory stream in postnatal and adult brains. Live imaging of Tuba1a-mutant neurons revealed slowed migration and increased neuronal branching, which correlated with directionality alterations and perturbed nucleus-centrosome (N-C) coupling. Tuba1a mutation led to increased straightness of newly polymerized MTs, and structural modeling data suggest a conformational change in the α/β-tubulin heterodimer. We show that Tuba8, another α-tubulin isotype previously associated with cortical malformations, has altered function compared with Tuba1a. Our work shows that Tuba1a plays an essential, noncompensated role in neuronal saltatory migration in vivo and highlights the importance of MT flexibility in N-C coupling and neuronal-branching regulation during neuronal migration.

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