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Grenoble, France

Bouvard D.,Institute Albert Bonniot
Nature reviews. Molecular cell biology | Year: 2013

Integrins mediate cell-matrix and cell-cell interactions and integrate extracellular cues to the cytoskeleton and cellular signalling pathways. Integrin function on the cell surface is regulated by their activity switching such that intracellular proteins interacting with the integrin cytoplasmic domains increase or decrease integrin-ligand binding affinity. It is widely accepted that integrin activation by specific proteins is essential for cell adhesion and integrin linkage to the actin cytoskeleton. However, there is also increasing evidence that integrin-inactivating proteins are crucial for appropriate integrin function in vitro and in vivo and that the regulation of integrin-ligand interactions is a fine-tuned balancing act between inactivation and activation.

Carrire L.,CEA Saclay Nuclear Research Center | Graziani S.,CEA Saclay Nuclear Research Center | Graziani S.,Directorate General of Armaments | Alibert O.,French Atomic Energy Commission | And 17 more authors.
Nucleic Acids Research | Year: 2012

RNA polymerase (Pol) III synthesizes the tRNAs, the 5S ribosomal RNA and a small number of untranslated RNAs. In vitro, it also transcribes short interspersed nuclear elements (SINEs). We investigated the distribution of Pol III and its associated transcription factors on the genome of mouse embryonic stem cells using a highly specific tandem ChIP-Seq method. Only a subset of the annotated class III genes was bound and thus transcribed. A few hundred SINEs were associated with the Pol III transcription machinery. We observed that Pol III and its transcription factors were present at 30 unannotated sites on the mouse genome, only one of which was conserved in human. An RNA was associated with >80 of these regions. More than 2200 regions bound by TFIIIC transcription factor were devoid of Pol III. These sites were associated with cohesins and often located close to CTCF-binding sites, suggesting that TFIIIC might cooperate with these factors to organize the chromatin. We also investigated the genome-wide distribution of the ubiquitous TFIIS variant, TCEA1. We found that, as in Saccharomyces cerevisiae, TFIIS is associated with class III genes and also with SINEs suggesting that TFIIS is a Pol III transcription factor in mammals. © 2011 The Author(s).

Khochbin S.,French Institute of Health and Medical Research | Khochbin S.,Joseph Fourier University | Khochbin S.,Institute Albert Bonniot
Chemistry and Biology | Year: 2011

An audacious bet on transforming histone H4 into a real-time sensor probe has been won by the group of Minoru Yoshida, who designed the first FRET probes capable of signaling the occurrence of dynamic site-specific acetylations in live cells. © 2011 Elsevier Ltd.

Hiriart E.,French Institute of Health and Medical Research | Hiriart E.,Joseph Fourier University | Verdel A.,French Institute of Health and Medical Research | Verdel A.,Joseph Fourier University | Verdel A.,Institute Albert Bonniot
Chromosome Research | Year: 2013

Germ cell differentiation, the cellular process by which a diploid progenitor cell produces by meiotic divisions haploid cells, is conserved from the unicellular yeasts to mammals. Over the recent years, yeast germ cell differentiation process has proven to be a powerful biological system to identify and study several long noncoding RNAs (lncRNAs) that play a central role in regulating cellular differentiation by acting directly on chromatin. Remarkably, in the well-studied budding yeast Saccharomyces cerevisiae and fission yeast Schizosaccharomyces pombe, the lncRNA-based chromatin regulations of germ cell differentiation are quite different. In this review, we present an overview of these regulations by focusing on the mechanisms and their respective functions both in S. cerevisiae and in S. pombe. Part of these lncRNA-based chromatin regulations may be conserved in other eukaryotes and play critical roles either in the context of germ cell differentiation or, more generally, in the development of multicellular organisms. © 2013 The Author(s).

Bednar J.,CNRS Physics Laboratory | Bednar J.,Charles University | Bednar J.,Academy of Sciences of the Czech Republic | Dimitrov S.,Institute Albert Bonniot
FEBS Journal | Year: 2011

About a decade ago, the elastic properties of a single chromatin fiber and, subsequently, those of a single nucleosome started to be explored using optical and magnetic tweezers. These techniques have allowed direct measurements of several essential physical parameters of individual nucleosomes and nucleosomal arrays, including the forces responsible for the maintenance of the structure of both the chromatin fiber and the individual nucleosomes, as well as the mechanism of their unwinding under mechanical stress. Experiments on the assembly of individual chromatin fibers have illustrated the complexity of the process and the key role of certain specific components. Nevertheless a substantial disparity exists in the data reported from various experiments. Chromatin, unlike naked DNA, is a system which is extremely sensitive to environmental conditions, and studies carried out under even slightly different conditions are difficult to compare directly. In this review we summarize the available data and their impact on our knowledge of both nucleosomal structure and the dynamics of nucleosome and chromatin fiber assembly and organization. Single molecule experiments on nucleosomes or chromatin arrays have brought new insight into the mechanical properties of chromatin and its integrity and stability. In this review we summarize available data from such studies and their impact on our knowledge of both nucleosomal structure and the dynamics of nucleosome and chromatin fiber assembly and organization © Journal compilation © 2011 FEBS. No claim to original French government works.

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