the department is focused on various topics which are all related to the
control of eucaryotic cells proliferation, more specifically regarding chromatin and cell dynamics :
Histone demethylases in development and
in cancer (Luisa DI STEFANO)
Our goal is to shed light on the mechanisms that control chromatin structure and gene transcription during Drosophila development and in cancer cell lines. The scientific objective of the team is to unravel the network of interplay of the histone demethylase LSD1 at the genetic and molecular level. We aim to answer three primary questions using genetic screens, high-throughput genomic technologies, biochemical and in vivo assays :
1) Which proteins and/or noncoding RNA direct LSD1 targeting and to which genomic regions?
2) Which signalling pathways control LSD1 activity and in which context?
3) How does LSD1 misregulation affect normal development and contribute to tumorigenesis?
Keywords : Chromatin, Transcription, Histone demethylases, Drosophila, Cancer.
of polycomb/MLL-group genes in transcriptional control of target genes
The team is focused on the mechanisms of regulation of the Ink4aB/arf tumor suppressor locus by the MLL and Polycomb complexes. We are interested in the molecular mechanisms involved in stability of cellular senescence after oncogenic stress and in the signalling pathways in OIS allowing rapid induction of genes controlled by MLL/Polycomb complexes.
1) This work has allowed us to demonstrate that some microRNA specifically control a subset Polycomb genes in senescence cells therefore participating in the stability of cellular senescence. 2) We have demonstrated that the MSK1 kinase is induced in OIS and plays an important role in expression of INK4 genes. MSK1 allows the eviction of the Polycomb complex from the INK4a locus and permits rapid expression of this locus following oncogenic stress.
Keywords: Polycomb, MLL, Epigenetic, Senescence
Chromatin and DNA repair (Gaëlle LEGUBE)
Among the types of damage, DNA Double Strands Breaks (DSBs) (provoked by various environmental stresses) are the most deleterious, as illustrated by the variety of human diseases associated with DSB repair defects. Repair of DSB into the chromatin context raises several questions that we aim to address in the lab.
Using an experimental system we recently developed (called DIvA for DSB Inducible via AsiSI), that allows the induction of multiple sequence-specific DSBs widespread across the genome, we propose to investigate several uncovered aspects of the relationship between chromatin and DSB repair. By high-throughput genomic and proteomic technologies we try (i) to understand the contribution of chromatin in the DSB repair pathway choice, (ii) to describe more thoroughly the chromatin remodeling events that occur concomitantly to DSB to promote adequate repair, (iii) to elucidate the processes at work to restore epigenome integrity after DSB repair.
Keywords: DNA Double Strand Breaks repair, Chromatin, ChIP-seq
Apoptosis-dependent morphogenesis (Magali SUZANNE)
One of the key aim in developmental biology is to fully understand how specific organs are formed and shaped. To do so, it is important to determine and characterize the cellular mechanisms involved in tissue shape remodeling such as epithelium folding, a basic morphogenetic event essential to transform simple 2D epithelial sheets into 3D structures. Although recent studies reveal the cellular mechanisms involved in cell shape dynamics, the initial cellular mechanisms that trigger and coordinate tissue folding remain largely unknown.
Keywords : Morphogenesis, Apoptosis, Cytoskeleton, Live tissue, Drosophila
of cell division (Sylvie TOURNIER)
The fidelity of chromosome attachment and segregation during mitosis is crucial to preventing the formation of aneuploid cells, a phenotype frequently observed in cancer and genetic diseases. Kinetochores, protein structures that assemble at the centromeres of chromosomes must attach to microtubules (MTs) from opposite spindle poles prior anaphase. In the past decade, mass spectrometry-based proteomics greatly accelerated the elucidation of kinetochore composition in all eukaryotes. The challenges are now to identify the precise function of these proteins. Do they control microtubule dynamic at kinetochore? At what precise stage of mitosis do they work? Are they involved in the error correction? Are there alternative mechanisms involving for example chromosome arms separation, that are required for faithful mitosis?
The objective of our team is to identify fundamental mechanisms leading to aneuploidy. To this end, we are using an innovative approach that combines yeast genetics, quantitative microscopy and computer vision to highlight chromosome behavior in living cells.
Keywords : Mitosis, aneuploidy, cell division, biophysical modeling fission yeast
Chromatin and cell
proliferation (Didier TROUCHE)
The group investigates the role and regulation of chromatin modifications and chromatin modifying enzymes in mammalian cell fate. In recent years, we characterized the role of the histone acetyl transferase Tip60 and its associated protein p400 (an ATPase incorporating the histone variant H2A.Z) in genetic stability and cancer. We also investigated the role of the histone demethylase JMJD2A in cellular or molecular processes linked to cell proliferation. Finally, we studied the role of non coding RNAs in setting up the senescence-associated chromatin landscape during senescence induction. Our projects for the next five years are mainly the continuation of these studies, with an emphasis on integrative biology. We will make a great use of model organisms (mice in particular), investigate the global regulation and expression of the genome and characterize how families of chromatin modifying enzymes regulate chromatin modifications and cell fate in a concerted manner. These studies will provide major insights in our understanding of how the chromatin landscape is controlled temporally and spatially, allowing the correct response to extracellular or intracellular signals.
Keywords : chromatin, histone modifications, histone variants, chromatin modifying enzymes, mammalian cells proliferation, genetic stability, cancer
Cell migration and cancer
Cell migration is critically important in both physiological and pathological processes. Aberration of cell migration can cause a variety of problems including birth defect, immune problem, and cancer metastasis. Cell migration is generally classified into two principle types, individual and collective cell migration. Compared with the well characterized epithelial-mesenchymal transition (EMT) which is commonly fit in individual cell migration, collective cell migration still remains poorly understood. Border cell migration in Drosophila ovary has been used to study collective cell migration in vivo, and over a dozen genes critical in it have been identified by genetic screening. However, traditional methods limit our understanding of border cell migration in the dynamical, temporal and spatial patterns. Lately, we developed a novel photoactivatable-Rac (PA-Rac) to temporally and spatially control Rac activity as well as a Rac FRET biosensor to measure Rac activity, benefiting from an recently established ex vivo live time-lapse imaging. More recently, we built up a mathematic imaging processing to discriminate and quantify the rotation vs. non-rotation in a 3D context. With such several novel and traditional tools in hand, we propose to investigate two uncovered aspects of collective border cell migration: intercellular communication induced by PA-Rac; rotational and non-rotational collective migration modes. Moreover, we will introduce more biotechniques into our studies of not only collective cell migration but also tumorigenesis in breast cancer progression. These techniques include: a rapamycin-FRB-FKBP interaction controlled chemical perturbance system, and more optogenetics tools. In addition, we are also interested in cancer invasion and metastasis, in which we are focused on the control of focal adhesion kinase (FAK) pathway and focal adhesion dynamics. We will investigate a novel signaling control, its clinical significance, and introduce a novel caged inducible system to control focal adhesion dynamics for live imaging tracking.
Keywords : Cell migration, development, cancer