Mass Spectrometry and Proteomics Facility


Year of publication 2017

Sara Bizzotto, Ana Uzquiano, Florent Dingli, Dmitry Ershov, Anne Houllier, Guillaume Arras, Mark Richards, Damarys Loew, Nicolas Minc, Alexandre Croquelois, Anne Houdusse, Fiona Francis (2017 Dec 13)

Eml1 loss impairs apical progenitor spindle length and soma shape in the developing cerebral cortex.

Scientific reports : 17308 : DOI : 10.1038/s41598-017-15253-4 Learn more

The ventricular zone (VZ) of the developing cerebral cortex is a pseudostratified epithelium that contains progenitors undergoing precisely regulated divisions at its most apical side, the ventricular lining (VL). Mitotic perturbations can contribute to pathological mechanisms leading to cortical malformations. The HeCo mutant mouse exhibits subcortical band heterotopia (SBH), likely to be initiated by progenitor delamination from the VZ early during corticogenesis. The causes for this are however, currently unknown. Eml1, a microtubule (MT)-associated protein of the EMAP family, is impaired in these mice. We first show that MT dynamics are perturbed in mutant progenitor cells in vitro. These may influence interphase and mitotic MT mechanisms and indeed, centrosome and primary cilia were altered and spindles were found to be abnormally long in HeCo progenitors. Consistently, MT and spindle length regulators were identified in EML1 pulldowns from embryonic brain extracts. Finally, we found that mitotic cell shape is also abnormal in the mutant VZ. These previously unidentified VZ characteristics suggest altered cell constraints which may contribute to cell delamination.

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Lucie Hebert, Dorine Bellanger, Chloé Guillas, Antoine Campagne, Florent Dingli, Damarys Loew, Alice Fievet, Virginie Jacquemin, Tatiana Popova, Didier Jean, Fatima Mechta-Grigoriou, Raphaël Margueron, Marc-Henri Stern (2017 Oct 27)

Modulating BAP1 expression affects ROS homeostasis, cell motility and mitochondrial function.

Oncotarget : 72513-72527 : DOI : 10.18632/oncotarget.19872 Learn more

The tumor suppressor BAP1 associates with ASXL1/2 to form the core Polycomb complex PR-DUB, which catalyzes the removal of mono-ubiquitin from several substrates including histone H2A. This complex also mediates the poly-deubiquitination of HCFC1, OGT and PCG1-α, preventing them from proteasomal degradation. Surprisingly, considering its role in a Polycomb complex, no transcriptional signature was consistently found among BAP1-inactivated tumor types. It was hypothesized that BAP1 tumor suppressor activity could reside, at least in part, in stabilizing proteins through its poly-deubiquitinase activity. Quantitative mass spectrometry and gene expression arrays were used to investigate the consequences of BAP1 expression modulation in the NCI-H226 mesothelioma cell line. Analysis of differentially expressed proteins revealed enrichment in cytoskeleton organization, mitochondrial activity and ROS management, while gene expression analysis revealed enrichment in the epithelial-to-mesenchymal transition pathway. Functional assessments in BAP1 inactivated, BAP1 wild-type and BAP1 catalytically dead-expressing NCI-H226 and QR mesothelioma cell lines confirmed alteration of these pathways and demonstrated that BAP1 deubiquitinase activity was mandatory to maintain these phenotypes. Interestingly, monitoring intracellular ROS levels partly restored the morphology and the mitochondrial activity. Finally, the study suggests new tumorigenic and cellular functions of BAP1 and shows for the first time the interest of studying the proteome as readout of BAP1 inactivation.

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Alexandros Glentis, Philipp Oertle, Pascale Mariani, Aleksandra Chikina, Fatima El Marjou, Youmna Attieh, Francois Zaccarini, Marick Lae, Damarys Loew, Florent Dingli, Philemon Sirven, Marie Schoumacher, Basile G Gurchenkov, Marija Plodinec, Danijela Matic Vignjevic (2017 Oct 15)

Cancer-associated fibroblasts induce metalloprotease-independent cancer cell invasion of the basement membrane.

Nature communications : 924 : DOI : 10.1038/s41467-017-00985-8 Learn more

At the stage of carcinoma in situ, the basement membrane (BM) segregates tumor cells from the stroma. This barrier must be breached to allow dissemination of the tumor cells to adjacent tissues. Cancer cells can perforate the BM using proteolysis; however, whether stromal cells play a role in this process remains unknown. Here we show that an abundant stromal cell population, cancer-associated fibroblasts (CAFs), promote cancer cell invasion through the BM. CAFs facilitate the breaching of the BM in a matrix metalloproteinase-independent manner. Instead, CAFs pull, stretch, and soften the BM leading to the formation of gaps through which cancer cells can migrate. By exerting contractile forces, CAFs alter the organization and the physical properties of the BM, making it permissive for cancer cell invasion. Blocking the ability of stromal cells to exert mechanical forces on the BM could therefore represent a new therapeutic strategy against aggressive tumors.Stromal cells play various roles in tumor establishment and metastasis. Here the authors, using an ex-vivo model, show that cancer-associated fibroblasts facilitate colon cancer cells invasion in a matrix metalloproteinase-independent manner, likely by pulling and stretching the basement membrane to form gaps.

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Guillaume Kellermann, Florent Dingli, Vanessa Masson, Daniel Dauzonne, Evelyne Ségal-Bendirdjian, Marie-Paule Teulade-Fichou, Damarys Loew, Sophie Bombard (2017 Mar 1)

Exploring the mechanism of inhibition of human telomerase by cysteine-reactive compounds.

FEBS letters : 591 : 863-874 : DOI : 10.1002/1873-3468.12589 Learn more

Telomerase is an almost universal cancer target that consists minimally of a core protein (hTERT) and an RNA (hTR). Some inhibitors of this enzyme are thought to function by the covalent binding to one or several cystein residues; however, this inhibition mechanism has never been investigated because of the difficulty in producing telomerase. In the present study, we use a recent method to produce recombinant hTERT to analyse the effect of cysteine reactive inhibitors on telomerase. Using mass-spectrometry (MS) and mutagenesis analysis, we identify several targeted residues in separated domains of the hTERT protein and show that cysteine-reactive reagents abolish the interaction with the CR4/5 region of hTR. This article is protected by copyright. All rights reserved.

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Year of publication 2016

Cédric M Blouin, Yannick Hamon, Pauline Gonnord, Cédric Boularan, Jérémy Kagan, Christine Viaris de Lesegno, Richard Ruez, Sébastien Mailfert, Nicolas Bertaux, Damarys Loew, Christian Wunder, Ludger Johannes, Guillaume Vogt, Francesc-Xabier Contreras, Didier Marguet, Jean-Laurent Casanova, Céline Galès, Hai-Tao He, Christophe Lamaze (2016 Aug 9)

Glycosylation-Dependent IFN-γR Partitioning in Lipid and Actin Nanodomains Is Critical for JAK Activation.

Cell : 920-34 : DOI : 10.1016/j.cell.2016.07.003 Learn more

Understanding how membrane nanoscale organization controls transmembrane receptors signaling activity remains a challenge. We studied interferon-γ receptor (IFN-γR) signaling in fibroblasts from homozygous patients with a T168N mutation in IFNGR2. By adding a neo-N-glycan on IFN-γR2 subunit, this mutation blocks IFN-γ activity by unknown mechanisms. We show that the lateral diffusion of IFN-γR2 is confined by sphingolipid/cholesterol nanodomains. In contrast, the IFN-γR2 T168N mutant diffusion is confined by distinct actin nanodomains where conformational changes required for Janus-activated tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) activation by IFN-γ could not occur. Removing IFN-γR2 T168N-bound galectins restored lateral diffusion in lipid nanodomains and JAK/STAT signaling in patient cells, whereas adding galectins impaired these processes in control cells. These experiments prove the critical role of dynamic receptor interactions with actin and lipid nanodomains and reveal a new function for receptor glycosylation and galectins. Our study establishes the physiological relevance of membrane nanodomains in the control of transmembrane receptor signaling in vivo. VIDEO ABSTRACT.

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Lisa Prendergast, Sebastian Müller, Yiwei Liu, Hongda Huang, Florent Dingli, Damarys Loew, Isabelle Vassias, Dinshaw J Patel, Kevin F Sullivan, Geneviève Almouzni (2016 Jun 11)

The CENP-T/-W complex is a binding partner of the histone chaperone FACT.

Genes & development : 1313-26 : DOI : 10.1101/gad.275073.115 Learn more

The CENP-T/-W histone fold complex, as an integral part of the inner kinetochore, is essential for building a proper kinetochore at the centromere in order to direct chromosome segregation during mitosis. Notably, CENP-T/-W is not inherited at centromeres, and new deposition is absolutely required at each cell cycle for kinetochore function. However, the mechanisms underlying this new deposition of CENP-T/-W at centromeres are unclear. Here, we found that CENP-T deposition at centromeres is uncoupled from DNA synthesis. We identified Spt16 and SSRP1, subunits of the H2A-H2B histone chaperone facilitates chromatin transcription (FACT), as CENP-W binding partners through a proteomic screen. We found that the C-terminal region of Spt16 binds specifically to the histone fold region of CENP-T/-W. Furthermore, depletion of Spt16 impairs CENP-T and CENP-W deposition at endogenous centromeres, and site-directed targeting of Spt16 alone is sufficient to ensure local de novo CENP-T accumulation. We propose a model in which the FACT chaperone stabilizes the soluble CENP-T/-W complex in the cell and promotes dynamics of exchange, enabling CENP-T/-W deposition at centromeres.

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