UMR3348 – Genotoxic stress and Cancer

Unit publications

Year of publication 2016

Catharina von Nicolai, Åsa Ehlén, Charlotte Martin, Xiaodong Zhang, Aura Carreira (2016 Sep 15)

A second DNA binding site in human BRCA2 promotes homologous recombination.

Nature communications : 12813 : DOI : 10.1038/ncomms12813 Learn more
Summary

BRCA2 tumour-suppressor protein is well known for its role in DNA repair by homologous recombination (HR); assisting the loading of RAD51 recombinase at DNA double-strand breaks. This function is executed by the C-terminal DNA binding domain (CTD) which binds single-stranded (ss)DNA, and the BRC repeats, which bind RAD51 and modulate its assembly onto ssDNA. Paradoxically, analysis of cells resistant to DNA damaging agents missing the CTD restore HR proficiency, suggesting another domain may take over its function. Here, we identify a region in the N terminus of BRCA2 that exhibits DNA binding activity (NTD) and provide evidence for NTD promoting RAD51-mediated HR. A missense variant detected in breast cancer patients located in the NTD impairs HR stimulation on dsDNA/ssDNA junction containing substrates. These findings shed light on the function of the N terminus of BRCA2 and have implications for the evaluation of breast cancer variants.

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Vittorio Calderone, Javier Gallego, Gonzalo Fernandez-Miranda, Ester Garcia-Pras, Carlos Maillo, Annalisa Berzigotti, Marc Mejias, Felice-Alessio Bava, Ana Angulo-Urarte, Mariona Graupera, Pilar Navarro, Jaime Bosch, Mercedes Fernandez, Raul Mendez (2016 Apr 1)

Sequential Functions of CPEB1 and CPEB4 Regulate Pathologic Expression of Vascular Endothelial Growth Factor and Angiogenesis in Chronic Liver Disease.

Gastroenterology : 982-97.e30 : DOI : 10.1053/j.gastro.2015.11.038 Learn more
Summary

Vascular endothelial growth factor (VEGF) regulates angiogenesis, yet therapeutic strategies to disrupt VEGF signaling can interfere with physiologic angiogenesis. In a search for ways to inhibit pathologic production or activities of VEGF without affecting its normal production or functions, we investigated the post-transcriptional regulation of VEGF by the cytoplasmic polyadenylation element-binding proteins CPEB1 and CPEB4 during development of portal hypertension and liver disease.

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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 : 16793-805 : DOI : 10.18632/oncotarget.7589 Learn more
Summary

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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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 Learn more
Summary

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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Andreas P Frei*, Felice-Alessio Bava*, Eli R Zunder, Elena W Y Hsieh, Shih-Yu Chen, Garry P Nolan, Pier Federico Gherardini. *co-first, equal contributors (2016 Mar 1)

Highly multiplexed simultaneous detection of RNAs and proteins in single cells.

Nature methods : 269-75 : DOI : 10.1038/nmeth.3742 Learn more
Summary

To enable the detection of expression signatures specific to individual cells, we developed PLAYR (proximity ligation assay for RNA), a method for highly multiplexed transcript quantification by flow and mass cytometry that is compatible with standard antibody staining. When used with mass cytometry, PLAYR allowed for the simultaneous quantification of more than 40 different mRNAs and proteins. In primary cells, we quantified multiple transcripts, with the identity and functional state of each analyzed cell defined on the basis of the expression of a separate set of transcripts or proteins. By expanding high-throughput deep phenotyping of cells beyond protein epitopes to include RNA expression, PLAYR opens a new avenue for the characterization of cellular metabolism.

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Chrystelle Aillaud, Christophe Bosc, Yasmina Saoudi, Eric Denarier, Leticia Peris, Laila Sago, Nicolas Taulet, Adeline Cieren, Olivia Tort, Maria M Magiera, Carsten Janke, Virginie Redeker, Annie Andrieux, Marie-Jo Moutin (2016 Feb 15)

Evidence for new C-terminally truncated variants of α- and β-tubulins.

Molecular biology of the cell : 640-53 : DOI : 10.1091/mbc.E15-03-0137 Learn more
Summary

Cellular α-tubulin can bear various carboxy-terminal sequences: full-length tubulin arising from gene neosynthesis is tyrosinated, and two truncated variants, corresponding to detyrosinated and Δ2 α‑tubulin, result from the sequential cleavage of one or two C-terminal residues, respectively. Here, by using a novel antibody named 3EG that is highly specific to the -EEEG C-terminal sequence, we demonstrate the occurrence in neuronal tissues of a new αΔ3‑tubulin variant corresponding to α1A/B‑tubulin deleted of its last three residues (EEY). αΔ3‑tubulin has a specific distribution pattern: its quantity in the brain is similar to that of αΔ2-tubulin around birth but is much lower in adult tissue. This truncated α1A/B-tubulin variant can be generated from αΔ2-tubulin by the deglutamylases CCP1, CCP4, CCP5, and CCP6 but not by CCP2 and CCP3. Moreover, using 3EG antibody, we identify a C‑terminally truncated β-tubulin form with the same -EEEG C-terminal sequence. Using mass spectrometry, we demonstrate that β2A/B-tubulin is modified by truncation of the four C-terminal residues (EDEA). We show that this newly identified βΔ4-tubulin is ubiquitously present in cells and tissues and that its level is constant throughout the cell cycle. These new C-terminally truncated α- and β-tubulin variants, both ending with -EEEG sequence, are expected to regulate microtubule physiology. Of interest, the αΔ3-tubulin seems to be related to dynamic microtubules, resembling tyrosinated-tubulin rather than the other truncated variants, and may have critical function(s) in neuronal development.

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Year of publication 2015

Valeria Giangarrà, Ana Igea, Chiara Lara Castellazzi, Felice-Alessio Bava*, Raul Mendez*. *co-last,co-corresponding author (2015 Sep 23)

Global Analysis of CPEBs Reveals Sequential and Non-Redundant Functions in Mitotic Cell Cycle.

PloS one : e0138794 : DOI : 10.1371/journal.pone.0138794 Learn more
Summary

CPEB (Cytoplasmic Polyadenylation Element Binding) proteins are a family of four RNA-binding proteins that regulate the translation of maternal mRNAs controlling meiotic cell cycle progression. But CPEBs are not limited to the transcriptionally silent germline; they are also expressed, in various combinations, in somatic cells, yet their role in regulation of mitosis-related gene expression is largely unknown. Deregulation of CPEB1 and CPEB4 have been linked to tumor development. However, a systematic analysis addressing their requirements for the temporal regulation of mitotic gene expression has yet to be performed. This study addresses the requirements of each of the four CPEBs for mitotic phase transitions, with a particular focus on cytoplasmic polyadenylation and translational regulation. We demonstrate that CPEB3 is the only member dispensable for mitotic cell division, whereas the other three members, CPEB1, 2, and 4, are essential to successful mitotic cell division. Thus, CPEB1 is required for prophase entry, CPEB2 for metaphase and CPEB4 for cytokinesis. These three CPEBs have sequential non-redundant functions that promote the phase-specific polyadenylation and translational activation of CPE-regulated transcripts in the mitotic cell cycle.

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Year of publication 2013

Carsten Janke (2013 Oct 16)

Mysterious modification of tubulin.

Nature Reviews Molecular Cell BiologyNature Reviews Molecular Cell Biology Learn more
L Boussemart, E Routier, C Mateus, K Opletalova, G Sebille, N Kamsu-Kom, M Thomas, S Vagner, M Favre, G Tomasic, J Wechsler, L Lacroix, C Robert (2013 Jun 1)

Prospective study of cutaneous side-effects associated with the BRAF inhibitor vemurafenib: a study of 42 patients.

Annals of oncology : official journal of the European Society for Medical Oncology : 1691-7 : DOI : 10.1093/annonc/mdt015 Learn more
Summary

BRAF inhibitors are being developed for the treatment of metastatic melanoma harboring a V600E mutation. The use of vemurafenib significantly increases progression-free survival (PFS) and overall survival (OS) in this population of patients, but is associated with numerous adverse skin reactions.

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Felice-Alessio Bava, Carolina Eliscovich, Pedro G Ferreira, Belen Miñana, Claudia Ben-Dov, Roderic Guigó, Juan Valcárcel, Raúl Méndez (2013 Mar 7)

CPEB1 coordinates alternative 3′-UTR formation with translational regulation.

Nature : 121-5 : DOI : 10.1038/nature11901 Learn more
Summary

More than half of mammalian genes generate multiple messenger RNA isoforms that differ in their 3′ untranslated regions (3′ UTRs) and therefore in regulatory sequences, often associated with cell proliferation and cancer; however, the mechanisms coordinating alternative 3′-UTR processing for specific mRNA populations remain poorly defined. Here we report that the cytoplasmic polyadenylation element binding protein 1 (CPEB1), an RNA-binding protein that regulates mRNA translation, also controls alternative 3′-UTR processing. CPEB1 shuttles to the nucleus, where it co-localizes with splicing factors and mediates shortening of hundreds of mRNA 3′ UTRs, thereby modulating their translation efficiency in the cytoplasm. CPEB1-mediated 3′-UTR shortening correlates with cell proliferation and tumorigenesis. CPEB1 binding to pre-mRNAs not only directs the use of alternative polyadenylation sites, but also changes alternative splicing by preventing U2AF65 recruitment. Our results reveal a novel function of CPEB1 in mediating alternative 3′-UTR processing, which is coordinated with regulation of mRNA translation, through its dual nuclear and cytoplasmic functions.

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Year of publication 2012

Laure Weill, Eulàlia Belloc, Felice-Alessio Bava, Raúl Méndez (2012 Jun 6)

Translational control by changes in poly(A) tail length: recycling mRNAs.

Nature structural & molecular biology : 577-85 : DOI : 10.1038/nsmb.2311 Learn more
Summary

Beyond the well-known function of poly(A) tail length in mRNA stability, recent years have witnessed an explosion of information about how changes in tail length and the selection of alternative polyadenylation sites contribute to the translational regulation of a large portion of the genome. The mechanisms and factors mediating nuclear and cytoplasmic changes in poly(A) tail length have been studied in great detail, the targets of these mechanisms have been identified–in some cases by genome-wide screenings–and changes in poly(A) tail length are now implicated in a number of physiological and pathological processes. However, in very few cases have all three levels–mechanisms, targets and functions–been studied together.

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Year of publication 1976

G Fekete, T Nyári, M Kozlovszky (1976 Jan 1)

[Supporting role of the fibula in tibial fractures].

Magyar traumatologia, orthopaedia es helyreallito sebeszet : 14-22 Learn more
Summary

The possibilities of the supporting effect of the fibula and of its preclusion are discussed. The indication of the fibulotomia is dealt with. According to the authors’ standpoint in the case of the anatomical reposition of the tibial fracture and after its staple synthesis the supporting effect of the fibula is not be be feared. In these cases the reposition and the osteosynthesis of the fibula neutralize fairly well also the motive forces acting on the tibial fracture.

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