Research Thematics
News
CALL for NEW RESEARCH GROUP LEADERS
We are opening two distinct calls for new research group leaders. We encourage both young and already established outstanding researchers to apply. The deadline for applications is July 1st 2017. Selected applicants will be interviewed in October 2017.
Chaperoning histones and controlling genome function
Histone proteins are critical components of chromatin and the incorporation of different histone variants modulates nucleosome stability. Deposition of histones at the right time and the correct place in the genome is tightly controlled by specific histone chaperone complexes. In its last study , the team of Aline Probst and Christophe Tatout characterized the Arabidopsis ATRX (Alpha Thalassemia-mental Retardation X-linked) homologue. Using reverse genetic approaches along with genome wide analyses Duc et al show that loss of ATRX modulates the cellular balance between canonical H3.1 and its variant H3.3 and leads to reduced H3.3 deposition at set of genes with elevated H3.3 occupancy and high gene expression. This study further elucidates the network of histone chaperones in plants and reveals a specific role for ATRX in histone H3.3 deposition.
This work is published in The Plant Cell (Duc et al., 2017).
FXRα a new actor of germinal stem cells fate.
The FXRα nuclear receptor (Farnesoid-X-Receptor alpha) is a key factor controlling the male sex hormone synthesis within the testis. However, its roles in male germ cell homeostasis have not yet been studied. Using a phenotyping approach of Fxra deficient mice, the team of David Volle has characterized unexpected roles of FXRa with germ cell lineage. There, FXRa is involved in the establishment and the maintenance of undifferentiated germ cell pool and in turn, influences male fertility during aging.
This study is published in Stem Cell Reports (Martinot et al., 2017)
INDEPTH : The GReD, in collaboration with LIMOS laboratory, holds the first COST-Action coordinated by Clermont Auvergne University (UCA)
GReD and LIMOS laboratories are happy to inform you that their COST-action project entitled «Impact of Nuclear Domains on Gene Expression and Plant Traits » (INDEPTH) has been awarded. This pan-european project, coordinated by Pr Christophe Tatout (GReD) in collaboration with Pr Rémy Malgouyres (LIMOS), involves for the next 4 years more than 50 laboratories over 19 countries. INDEPTH will decipher how nuclear architecture, chromatin organization and gene expression are connected and modified in response to internal and external cues in plants. To address this challenge, the INDEPTH Action gathers a network bringing state-of-the-art technologies and fostering multidisciplinary approaches at research, training, education and industrial levels in high- and super-resolution microscopy, 3D image analysis and software development, chromatin domain mapping, genomics, bioinformatics and plant phenotyping. INDEPTH is the first cost-ation coordinated by UCA.
Les Doctorants du GReD à l’honneur lors des JED 2017.
Houda TABBAL, doctorante dans l’équipe « Pathophysiologie moléculaire des tissus surrénaux et endocriniens » et Alexandre CHAMPROUX, doctorant dans l’équipe « Mécanismes de l'infertilité mâle post-testiculaire », ont tous deux été primés lors des Journées de l’école Doctorale 2017.
Male infertility, toward new molecular causes .
Bile acids are molecules with endocrine activities controlling several physiological functions such as immunity and glucose homeostasis. Recently, they have also been shown to be involved in testicular physiology and as a cause of male fertility in experimental models. By the mean of mouse models and pharmacological approaches, the team of David Volle revealed the unexpected presence of alternative pathways, involving the Nuclear Receptor CAR (Constitutive-Androstane-Receptor ; NR1I3), to mediate bile acid functions in testis.
This study is published in Scientific Reports (Martinot et al., 2017).
Weapons exchange in the battle between transposable elements and their host
The inactivation of transposable elements within genomes is insured by multiple epigenetic mechanisms. Olivier Mathieu's team has identified two genes required for repressing many transposable elements through a new molecular pathway independent of the main epigenetic modifications. Surprisingly, these genes could themselves have derived from transposable elements. This reveals that domestication of transposable elements by flowering plants’ genomes would have allowed emergence of a new mechanism to control activity of these invasive sequences. This study is published in Nature Communications (Ikeda et al., 2017).
The LINC complex contributes to heterochromatin organisation and transcriptional gene silencing in plants
The linker of nucleoskeleton and cytoskeleton (LINC) complex is an evolutionarily well-conserved protein bridge connecting the cytoplasmic and nuclear compartments across the nuclear membrane. Recent investigations have highlighted its function in nuclear morphology and meiosis. The new study performed by the team of Aline Probst and Christophe Tatout brings new insights into LINC complex function in plants. Using 3D imaging and molecular techniques the authors reveal that plants carrying mutations in this complex show release of transcriptional silencing as well as a decompaction of heterochromatic sequences. Therefore, the plant LINC complex contributes to proper heterochromatin organisation and positioning at the nuclear periphery, illustrating the important function of the nuclear envelope in the regulation of genome expression.
This study has been published in Journal of Cell Science (Poulet et al., 2017)
The journey of a thousand piRNAs begins with a single Dot
Among the several kinds of non-coding small RNAs, piRNAs (Piwi-interacting RNAs) are the ‘transposon-silencers’. They occur within the gonads of animals, protecting the cellular genome from transposable elements. One of the most mysterious question is how piRNAs are transcribed and processed inside the cell. Now Chantal Vaury’s lab brings new data into the biosynthesis of piRNAs. Their study, published recently in Nature Comm (Dennis & al., Nat Commun, 2016 Dec 8;7:13739. doi: 10.1038/ncomms13739), shows that the precursor transcripts of piRNAs are exported out of the nucleus by specific exporter proteins-Nxt1,Nxf1 and that the export itself directs the assembly of Yb bodies which are the cytoplasmic maturation centres of piRNAs. Chantal’s lab has been actively studying piRNA production for the past years, using the ovarian tissue of the fruit fly Drosophila melanogaster as a model. In 2013, they discovered ‘Dot COM’ – a single bright spot within the nuclei of ovarian follicular cells where piRNA precursor transcripts accumulate before to be processed. This year their new study has revealed that the precursors travel away from the site of transcription in the DNA to DOT COM, with the help of exportins and exon-junction complex (EJC) proteins. The study opens new possibilities of research in the piRNA and transposable element regulation fields.
Adrenal gland differentiation: positive antagonism
Endocrine activity of the adrenal glands is essential for body homeostasis and depends on the differentiation of two concentric cellular zones. Using transgenic mouse models, Pierre Val’s team has shown that this zonal differentiation relies on a double antagonistic interaction between two signalling pathways. They further show that this antagonism inhibits development of aggressive tumours in mouse models and patients. This study is published in Nature Communications (Drelon et al., 2016) .
In a few words...
The GReD is a Research Center at Clermont-Ferrand, capital of the Auvergne region of central France. Created in 2008, the GReD is supported by the University of Auvergne, the University Blaise Pascal, the CNRS (UMR6293) and the INSERM (U1103). The center is composed of 10 research groups (totalling 130 people in April 2014) and is situated on the neighbouring campuses ...
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