UMR3348 – Intégrité du génome, ARN et cancer

Publications de l’unité

Année de publication : 2016

Hélène Colman, Catherine Le Berre-Scoul, Céline Hernandez, Sandra Pierredon, Audrey Bihouée, Rémi Houlgatte, Stephan Vagner, Arielle R Rosenberg, Cyrille Féray (2016 May 27)

Correction for Colman et al., Genome-Wide Analysis of Host mRNA Translation during Hepatitis C Virus Infection.

Journal of virology : 5846 : DOI : 10.1128/JVI.00507-16 En savoir plus
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Diana Passaro, Christine Tran Quang, Jacques Ghysdael (2016 May 1)

Microenvironmental cues for T-cell acute lymphoblastic leukemia development.

Immunological reviews : 156-72 : DOI : 10.1111/imr.12402 En savoir plus
Résumé

Intensive chemotherapy regimens have led to a substantial improvement in the cure rate of patients suffering from T-cell acute lymphoblastic leukemia (T-ALL). Despite this progress, about 15% and 50% of pediatric and adult cases, respectively, show resistance to treatment or relapse with dismal prognosis, calling for further therapeutic investigations. T-ALL is an heterogeneous disease, which presents intrinsic alterations leading to aberrant expression of transcription factors normally involved in hematopoietic stem/progenitor cell development and mutations in genes implicated in the regulation of cell cycle progression, apoptosis, and T-cell development. Gene expression profiling allowed the classification of T-ALL into defined molecular subgroups that mostly reflects the stage of their differentiation arrest. So far this knowledge has not translated into novel, targeted therapy. Recent evidence points to the importance of extrinsic signaling cues in controlling the ability of T-ALL to home, survive, and proliferate, thus offering the perspective of new therapeutic options. This review summarizes the present understanding of the interactions between hematopoietic cells and bone marrow/thymic niches during normal hematopoiesis, describes the main signaling pathways implicated in this dialog, and finally highlights how malignant T cells rely on specific niches to maintain their ability to sustain and propagate leukemia.

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Gary Borisy, Rebecca Heald, Jonathon Howard, Carsten Janke, Andrea Musacchio, Eva Nogales (2016 Apr 22)

Microtubules: 50 years on from the discovery of tubulin.

Nature reviews. Molecular cell biology : 322-8 : DOI : 10.1038/nrm.2016.45 En savoir plus
Résumé

Next year will be the 50th anniversary of the discovery of tubulin. To celebrate this discovery, six leaders in the field of microtubule research reflect on key findings and technological breakthroughs over the past five decades, discuss implications for therapeutic applications and provide their thoughts on what questions need to be addressed in the near future.

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F Macari, Y El-Houfi, G Boldina, H Xu, S Khoury-Hanna, J Ollier, L Yazdani, G Zheng, I Bièche, N Legrand, D Paulet, S Durrieu, A Byström, S Delbecq, B Lapeyre, L Bauchet, J Pannequin, F Hollande, T Pan, M Teichmann, S Vagner, A David, A Choquet, D Joubert (2016 Apr 7)

TRM6/61 connects PKCα with translational control through tRNAi(Met) stabilization: impact on tumorigenesis.

Oncogene : 1785-96 : DOI : 10.1038/onc.2015.244 En savoir plus
Résumé

Accumulating evidence suggests that changes of the protein synthesis machinery alter translation of specific mRNAs and participate in malignant transformation. Here we show that protein kinase C α (PKCα) interacts with TRM61, the catalytic subunit of the TRM6/61 tRNA methyltransferase. The TRM6/61 complex is known to methylate the adenosine 58 of the initiator methionine tRNA (tRNAi(Met)), a nuclear post-transcriptional modification associated with the stabilization of this crucial component of the translation-initiation process. Depletion of TRM6/61 reduced proliferation and increased death of C6 glioma cells, effects that can be partially rescued by overexpression of tRNAi(Met). In contrast, elevated TRM6/61 expression regulated the translation of a subset of mRNAs encoding proteins involved in the tumorigenic process and increased the ability of C6 cells to form colonies in soft agar or spheres when grown in suspension. In TRM6/61/tRNAi(Met)-overexpressing cells, PKCα overexpression decreased tRNAi(Met) expression and both colony- and sphere-forming potentials. A concomitant increase in TRM6/TRM61 mRNA and tRNAi(Met) expression with decreased expression of PKCα mRNA was detected in highly aggressive glioblastoma multiforme as compared with Grade II/III glioblastomas, highlighting the clinical relevance of our findings. Altogether, we suggest that PKCα tightly controls TRM6/61 activity to prevent translation deregulation that would favor neoplastic development.

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Anne Cammas, Magali Lacroix-Triki, Sandra Pierredon, Morgane Le Bras, Jason S Iacovoni, Marie-Paule Teulade-Fichou, Gilles Favre, Henri Roché, Thomas Filleron, Stefania Millevoi, Stéphan Vagner (2016 Mar 29)

hnRNP A1-mediated translational regulation of the G quadruplex-containing RON receptor tyrosine kinase mRNA linked to tumor progression.

Oncotarget : 7 : 16793-16805 : DOI : 10.18632/oncotarget.7589 En savoir plus
Résumé

The expression and role of RNA binding proteins (RBPs) controlling mRNA translation during tumor progression remains largely uncharacterized. Analysis by immunohistochemistry of the expression of hnRNP A1, hnRNPH, RBM9/FOX2, SRSF1/ASF/SF2, SRSF2/SC35, SRSF3/SRp20, SRSF7/9G8 in breast tumors shows that the expression of hnRNP A1, but not the other tested RBPs, is associated with metastatic relapse. Strikingly, hnRNP A1, a nuclear splicing regulator, is also present in the cytoplasm of tumor cells of a subset of patients displaying exceedingly worse prognosis. Expression of a cytoplasmic mutant of hnRNP A1 leads to increased translation of the mRNA encoding the tyrosine kinase receptor RON/MTS1R, known for its function in tumor dissemination, and increases cell migration in vitro. hnRNP A1 directly binds to the 5′ untranslated region of the RON mRNA and activates its translation through G-quadruplex RNA secondary structures. The correlation between hnRNP A1 and RON tumoral expression suggests that these findings hold clinical relevance.

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Juan S Martinez, Catharina von Nicolai, Taeho Kim, Åsa Ehlén, Alexander V Mazin, Stephen C Kowalczykowski, Aura Carreira (2016 Mar 29)

BRCA2 regulates DMC1-mediated recombination through the BRC repeats.

Proceedings of the National Academy of Sciences of the United States of America : 3515-20 : DOI : 10.1073/pnas.1601691113 En savoir plus
Résumé

In somatic cells, BRCA2 is needed for RAD51-mediated homologous recombination. The meiosis-specific DNA strand exchange protein, DMC1, promotes the formation of DNA strand invasion products (joint molecules) between homologous molecules in a fashion similar to RAD51. BRCA2 interacts directly with both human RAD51 and DMC1; in the case of RAD51, this interaction results in stimulation of RAD51-promoted DNA strand exchange. However, for DMC1, little is known regarding the basis and functional consequences of its interaction with BRCA2. Here we report that human DMC1 interacts directly with each of the BRC repeats of BRCA2, albeit most tightly with repeats 1-3 and 6-8. However, BRC1-3 bind with higher affinity to RAD51 than to DMC1, whereas BRC6-8 bind with higher affinity to DMC1, providing potential spatial organization to nascent filament formation. With the exception of BRC4, each BRC repeat stimulates joint molecule formation by DMC1. The basis for this stimulation is an enhancement of DMC1-ssDNA complex formation by the stimulatory BRC repeats. Lastly, we demonstrate that full-length BRCA2 protein stimulates DMC1-mediated DNA strand exchange between RPA-ssDNA complexes and duplex DNA, thus identifying BRCA2 as a mediator of DMC1 recombination function. Collectively, our results suggest unique and specialized functions for the BRC motifs of BRCA2 in promoting homologous recombination in meiotic and mitotic cells.

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Jeffrey J Nirschl, Maria M Magiera, Jacob E Lazarus, Carsten Janke, Erika L F Holzbaur (2016 Mar 22)

α-Tubulin Tyrosination and CLIP-170 Phosphorylation Regulate the Initiation of Dynein-Driven Transport in Neurons.

Cell reports : 2637-52 : DOI : 10.1016/j.celrep.2016.02.046 En savoir plus
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Motor-cargo recruitment to microtubules is often the rate-limiting step of intracellular transport, and defects in this recruitment can cause neurodegenerative disease. Here, we use in vitro reconstitution assays with single-molecule resolution, live-cell transport assays in primary neurons, computational image analysis, and computer simulations to investigate the factors regulating retrograde transport initiation in the distal axon. We find that phosphorylation of the cytoskeletal-organelle linker protein CLIP-170 and post-translational modifications of the microtubule track combine to precisely control the initiation of retrograde transport. Computer simulations of organelle dynamics in the distal axon indicate that while CLIP-170 primarily regulates the time to microtubule encounter, the tyrosination state of the microtubule lattice regulates the likelihood of binding. These mechanisms interact to control transport initiation in the axon in a manner sensitive to the specialized cytoskeletal architecture of the neuron.

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Lise Boussemart, Isabelle Girault, Hélène Malka-Mahieu, Christine Mateus, Emilie Routier, Margot Rubington, Nyam Kamsu-Kom, Marina Thomas, Gorana Tomasic, Sandrine Agoussi, Marie Breckler, Mélanie Laporte, Ludovic Lacroix, Alexander M Eggermont, Andrea Cavalcanti, Florent Grange, Julien Adam, Stéphan Vagner, Caroline Robert (2016 Mar 15)

Secondary Tumors Arising in Patients Undergoing BRAF Inhibitor Therapy Exhibit Increased BRAF-CRAF Heterodimerization.

Cancer research : 1476-84 : DOI : 10.1158/0008-5472.CAN-15-2900-T En savoir plus
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BRAF inhibitors (BRAFi) elicit therapeutic responses in metastatic melanoma, but alarmingly, also induce the formation of secondary benign and malignant skin tumors. Here, we report the emergence and molecular characterization of 73 skin and extracutaneous tumors in 31 patients who underwent BRAFi therapy. The majority of patients presented with classic epidermal tumors such as verrucous papillomas, keratoacanthomas, and squamous cell carcinomas (SCC). However, 15 patients exhibited new or rapidly progressing tumors distinct from these classic subtypes, such as lymph node metastasis, new melanomas, and genital and oral mucosal SCCs. Genotyping of the tumors revealed that oncogenic RAS mutations were found in 58% of the evaluable tumor samples (38/66) and 49% of the control tumors from patients not treated with BRAFi (30/62). Notably, proximity ligation assays demonstrated that BRAF-CRAF heterodimerization was increased in fixed tumor samples from BRAFi-treated patients compared with untreated patients. Our findings reveal that BRAF-CRAF complex formation is significantly associated with BRAFi treatment, and may therefore serve as a useful biomarker of BRAFi-induced cutaneous and extracutaneous tumor formation. Cancer Res; 76(6); 1476-84. ©2016 AACR.

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Samar Alsafadi, Alexandre Houy, Aude Battistella, Tatiana Popova, Michel Wassef, Emilie Henry, Franck Tirode, Angelos Constantinou, Sophie Piperno-Neumann, Sergio Roman-Roman, Martin Dutertre, Marc-Henri Stern (2016 Feb 5)

Cancer-associated SF3B1 mutations affect alternative splicing by promoting alternative branchpoint usage.

Nature communications : 10615 : DOI : 10.1038/ncomms10615 En savoir plus
Résumé

Hotspot mutations in the spliceosome gene SF3B1 are reported in ∼20% of uveal melanomas. SF3B1 is involved in 3′-splice site (3’ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1(R625/K666) mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3’ss. Modelling the differential junctions in SF3B1(WT) and SF3B1(R625/K666) cell lines demonstrates that the deregulated splice pattern strictly depends on SF3B1 status and on the 3’ss-sequence context. SF3B1(WT) knockdown or overexpression do not reproduce the SF3B1(R625/K666) splice pattern, qualifying SF3B1(R625/K666) as change-of-function mutants. Mutagenesis of predicted branchpoints reveals that the SF3B1(R625/K666)-promoted splice pattern is a direct result of alternative branchpoint usage. Altogether, this study provides a better understanding of the mechanisms underlying splicing alterations induced by mutant SF3B1 in cancer, and reveals a role for alternative branchpoints in disease.

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Tony Sourisseau, Carole Helissey, Céline Lefebvre, Florence Ponsonnailles, Hélène Malka-Mahieu, Ken A Olaussen, Fabrice André, Stephan Vagner, Jean-Charles Soria (2016 Jan 29)

Translational regulation of the mRNA encoding the ubiquitin peptidase USP1 involved in the DNA damage response as a determinant of Cisplatin resistance.

Cell cycle (Georgetown, Tex.) : 295-302 : DOI : 10.1080/15384101.2015.1120918 En savoir plus
Résumé

Cisplatin (cis-diaminedichloroplatin (II), CDDP) is part of the standard therapy for a number of solid tumors including Non-Small-Cell Lung Cancer (NSCLC). The initial response observed is in most cases only transient and tumors quickly become refractory to the drug. Tumor cell resistance to CDDP relies on multiple mechanisms, some of which still remain unknown. In search for such mechanisms, we examined the impact of CDDP on mRNA translation in a sensitive and in a matched resistant NSCLC cell line. We identified a set of genes whose mRNAs are differentially translated in CDDP resistant vs. sensitive cells. The translation of the mRNA encoding the Ubiquitin-Specific Peptidase 1 (USP1), a Ubiquitin peptidase with important function in multiple DNA repair pathways, is inhibited by CDDP exposure in the sensitive cells, but not in the resistant cells. This lack of down-regulation of USP1 expression at the translational level plays a primary role in CDDP resistance since inhibition of USP1 expression or activity by siRNA or the small molecule inhibitor ML323, respectively is sufficient to re-sensitize resistant cells to CDDP. We involved the USP1 mRNA translation as a major mechanism of CDDP resistance in NSCLC cells and suggest that USP1 could be evaluated as a candidate predictive marker and as a therapeutic target to overcome CDDP resistance. More generally, our results indicate that analysis of gene expression at the level of mRNA translation is a useful approach to identify new determinants of CDDP resistance.

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M Blosa, C Bursch, S Weigel, M Holzer, C Jäger, C Janke, R T Matthews, T Arendt, M Morawski (2016 Jan 1)

Reorganization of Synaptic Connections and Perineuronal Nets in the Deep Cerebellar Nuclei of Purkinje Cell Degeneration Mutant Mice.

Neural plasticity : 2828536 : DOI : 10.1155/2016/2828536 En savoir plus
Résumé

The perineuronal net (PN) is a subtype of extracellular matrix appearing as a net-like structure around distinct neurons throughout the whole CNS. PNs surround the soma, proximal dendrites, and the axonal initial segment embedding synaptic terminals on the neuronal surface. Different functions of the PNs are suggested which include support of synaptic stabilization, inhibition of axonal sprouting, and control of neuronal plasticity. A number of studies provide evidence that removing PNs or PN-components results in renewed neurite growth and synaptogenesis. In a mouse model for Purkinje cell degeneration, we examined the effect of deafferentation on synaptic remodeling and modulation of PNs in the deep cerebellar nuclei. We found reduced GABAergic, enhanced glutamatergic innervations at PN-associated neurons, and altered expression of the PN-components brevican and hapln4. These data refer to a direct interaction between ECM and synapses. The altered brevican expression induced by activated astrocytes could be required for an adequate regeneration by promoting neurite growth and synaptogenesis.

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Année de publication : 2015

Mónica T Fernandes, Marinella N Ghezzo, André B Silveira, Ravi K Kalathur, Vanda Póvoa, Ana R Ribeiro, Sílvia R Brandalise, Emmanuel Dejardin, Nuno L Alves, Jacques Ghysdael, João T Barata, José Andres Yunes, Nuno R dos Santos (2015 Dec 1)

Lymphotoxin-β receptor in microenvironmental cells promotes the development of T-cell acute lymphoblastic leukaemia with cortical/mature immunophenotype.

British journal of haematology : 736-51 : DOI : 10.1111/bjh.13760 En savoir plus
Résumé

Lymphotoxin-mediated activation of the lymphotoxin-β receptor (LTβR; LTBR) has been implicated in cancer, but its role in T-cell acute lymphoblastic leukaemia (T-ALL) has remained elusive. Here we show that the genes encoding lymphotoxin (LT)-α and LTβ (LTA, LTB) are expressed in T-ALL patient samples, mostly of the TAL/LMO molecular subtype, and in the TEL-JAK2 transgenic mouse model of cortical/mature T-ALL (Lta, Ltb). In these mice, expression of Lta and Ltb is elevated in early stage T-ALL. Surface LTα1 β2 protein is expressed in primary mouse T-ALL cells, but only in the absence of microenvironmental LTβR interaction. Indeed, surface LT expression is suppressed in leukaemic cells contacting Ltbr-expressing but not Ltbr-deficient stromal cells, both in vitro and in vivo, thus indicating that dynamic surface LT expression in leukaemic cells depends on interaction with its receptor. Supporting the notion that LT signalling plays a role in T-ALL, inactivation of Ltbr results in a significant delay in TEL-JAK2-induced leukaemia onset. Moreover, young asymptomatic TEL-JAK2;Ltbr(-/-) mice present markedly less leukaemic thymocytes than age-matched TEL-JAK2;Ltbr(+/+) mice and interference with LTβR function at this early stage delayed T-ALL development. We conclude that LT expression by T-ALL cells activates LTβR signalling in thymic stromal cells, thus promoting leukaemogenesis.

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Juan S Martinez, Céline Baldeyron, Aura Carreira (2015 Nov 13)

Molding BRCA2 function through its interacting partners.

Cell cycle (Georgetown, Tex.) : 3389-95 : DOI : 10.1080/15384101.2015.1093702 En savoir plus
Résumé

The role of the tumor suppressor BRCA2 has been shaped over 2 decades thanks to the discovery of its protein and nucleic acid partners, biochemical and structural studies of the protein, and the functional evaluation of germline variants identified in breast cancer patients. Yet, the pathogenic and functional effect of many germline mutations in BRCA2 remains undetermined, and the heterogeneity of BRCA2-associated tumors challenges the identification of causative variants that drive tumorigenesis. In this review, we propose an overview of the established and emerging interacting partners and functional pathways attributed to BRCA2, and we speculate on how variants altering these functions may contribute to cancer susceptibility.

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Diana Passaro, Christine Tran Quang, Jacques Ghysdael (2015 Sep 12)

Calcineurin/CXCR4 in T-ALL.

Oncoscience : 781-2 : DOI : 10.18632/oncoscience.238 En savoir plus
Résumé

The calcineurin/NFAT signaling pathway is implicated in a wide variety of biological processes, acting as a bridge pathway between calcium signals and gene expression. Although its role as an effector of immune responses figured prominently in early studies, it forms just one part of a larger picture. Indeed calcineurin has been shown to participate in the development and function of e.g. the immune, cardiovascular, nervous and musculoskeletal systems, and dysregulation of calcineurin/NFAT signaling contributes to pathologies affecting these tissues, in particular cancer [1].

Activation of the calcineurin/NFAT pathway was first observed in human lymphoma, as well as in mouse models of T cell acute lymphoblastic leukemia (T-ALL) and xenotransplanted human T-ALL [2]. In T-ALL, calcineurin activation is independent of preTCR/TCR signaling (the major calcineurin activator in normal T cell progenitors), but strongly depends upon micro-environmental signals. The fundamental, intrinsic role of calcineurin in T-ALL was demonstrated in several mouse models, in which conditional calcineurin genetic deletion was restricted to leukemic cells. Calcineurin was found essential to the physical and functional interactions that leukemic cells establish with supportive stromal cells, with its deletion resulting in impaired leukemia propagation, reduced cell survival, proliferation, migration and homing [3]. The therapeutic relevance of these findings was highlighted by preclinical studies showing strong anti-leukemic effects of calcineurin inhibitors (namely cyclosporin A or tacrolimus [FK506]) and long-term leukemia remission in a mouse T-ALL model when vincristine treatment was combined with calcineurin genetic inactivation [2, 3]. However, available calcineurin inhibitors appear suboptimal as potential therapeutic agents since they are associated with a number of toxic side effects [4], show clear off-target effects in T-ALL cells [3] and are expected to interfere with the anti-tumor immune response.

A recently developed, alternative option is to identify and target molecular pathways acting downstream of calcineurin and critical to T-ALL maintenance [5]. Our global transcriptomic analysis identified a large number of calcineurin-dependent genes in T-ALL, involved in an array of biological function, including the de-repression of known tumor suppressive pathways (e.g. CDKN1A) [3]. Although of high biological interest, these deregulations are not easily accessible for targeted therapy. In contrast, genes/proteins implicated in the adhesion/migration to the bone marrow microenvironment are promising candidates (i) for a thorough understanding of the factors that contribute to microenvironment-mediated support of leukemia progression and (ii) for the design of niche-targeted therapies. Along these lines, we linked calcineurin-dependent regulation of the adhesive/migratory properties of T-ALL cells to a boost of CXCR4 surface expression and the subsequent ability of the leukemic cells to respond to CXCL12 [5]. Upregulation of CXCR4 cell surface expression was also demonstrated in diagnostic T-ALL cases and primary xenograft in NSG mice [5][6]. The mechanism by which calcineurin affects CXCR4 trafficking is partially explained by the Cn-dependent up-regulation of cortactin [5], an actin-binding protein implicated in the regulation of endosomal trafficking [7]. Because actin polymerization is required for CXCR4 and other chemokine receptors trafficking to recycling vesicles, inhibition of cortactin expression in calcineurin-deficient T-ALL cells likely results in impaired actin dynamics in this endosomal compartment. Further investigation of the intrinsic function of CXCR4 in murine and human T-ALL revealed an important role of CXCL12/CXCR4 signaling in both survival/proliferation and homing/migration of leukemic cells to the supportive bone marrow niche [5][6]. Intravital multiphoton imaging and genetic studies revealed a strong interaction between T-ALL cells and CXCL12-expressing niche(s), and an essential supportive function of CXCL12 produced by vascular endothelial cells [6]. Local CXCL12 production, in addition to induction of CXCR4-dependent signaling cues will result in activation of T-ALL cells specific integrins, further stabilizing adhesion to integrin ligands expressing niche(s) and induction of additional pro-survival signals. In this scenario, the nature of the niche cells expressing the integrin ligands requires further characterization.

Strikingly, CXCR4 is also critical to leukemia initiating cell activity (LIC) in murine T-ALL and human xenografts [5][6], highlighting an unexpected, fundamental function of microenvironmental signals for T-ALL maintenance and progression. Many inhibitors of CXCL12 or CXCR4 have been developed and are tested in clinical studies in other pathological contexts, in particular other hematological malignancies [8]. However, only in T-ALL anti-CXCR4 monotherapy shows strong efficacy, suggesting a strong dependence of these tumor cells on Editorial CXCR4 signaling [6]. As relapse in T-ALL remains a challenging issue, these new data call for clinical trials to incorporate CXCR4 antagonists either as single agents following induction therapy, or as part of the first induction therapy regimen or later, during the consolidation phase.

In conclusion, the calcineurin/NFAT pathway acts as a fundamental bridge between microenvironmental-derived signals and T-ALL cells, mediating a complex crosstalk that is so far only partially dissected, but that already lead to the identification of novel targets of therapeutic relevance to T-ALL treatment.

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Carsten Janke, Michel O Steinmetz (2015 Aug 13)

Optochemistry to control the microtubule cytoskeleton.

The EMBO journal : 2114-6 : DOI : 10.15252/embj.201592415 En savoir plus
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