Epigenetic Mechanisms and Chromatin Architecture

Responsibles : Guillaume MOISSIARD (CRCN CNRS) & Frédéric PONTVIANNE (CRCN CNRS)

Epigenetic Mechanisms and Chromatin Architecture

TEAM :

DESCOMBIN Julie - ASI UPVD

MOISSIARD Guillaume - Chercheur CNRS

NICOLAU Mélody - Doctorante

PICART-PICOLO Ariadna - Doctorante

PICAULT Nathalie - Maître de conférences UPVD

PONTVIANNE Frédéric - Chercheur CNRS

Scientific context:

In the eukaryotic nucleus, a precise organization of chromatin is essential to ensure the proper expression of genes and to maintain cell integrity. Chromatin is mainly composed of genomic DNA wrapped around histone octamers, forming the nucleosome (Luger and Richmond, 1998). DNA methylation and histone modifications are important epigenetic marks regulating transcription of genes (Kouzarides, 2007). They also define the compaction state of chromatin. Heterochromatin, which is predominantly composed of DNA repeats and transposons, is highly condensed and transcriptionally repressed. Euchromatin, which is enriched in genes, is more relaxed and more permissive to transcription.

Research projects:

We are currently studying the mechanisms involved in the chromatin organization and its impact on gene expression using Arabidopsis thaliana as model organism. This organization is indeed very dynamic and can evolve depending on the cell type or in response to environmental stimuli (heat, light…) (Bourbousse et al. 2015; Sullivan et al. 2014).

In further details, we aim at:

  1. Mapping the chromatin regions localized at the nuclear periphery and within the nucleolus.
  2. Understanding the impact of subnuclear organization of chromatin on gene expression.
  3. Identifying the cellular factors involved in this subnuclear organization of chromatin.
  4. Discovering new epigenetic components.

Experimental approaches:

We are using next generation sequencing (NGS) approaches to map, at the genomic level, the chromatin organization within the plant cell nucleus. We are also developing biochemical tools to study interactions between chromatin and proteins using chromatin immunoprecipitation (ChIP-seq) experiments, and to identify protein complexes by immunoprecipitation coupled to Liquid chromatography–mass spectrometry (LC-MS) analyses. Finally, microscopic approaches allow us to study nuclear organization at the cell level.

In parallel, we are currently developing forward genetic screens to identify, in an unbiased manner, new epigenetic factors involved in heterochromatin silencing in plants.

Major publications:

Pontvianne F, et al. (2016) Identification of Nucleolus-Associated Chromatin Domains Reveals a Role for the Nucleolus in 3D Organization of the A. thaliana Genome. Cell Rep. (doi: 10.1016/j.celrep.2016.07.016.)

Moissiard G et al., (2014) Transcriptional gene silencing by Arabidopsis microrchidia homologues involves the formation of heteromers. Proc Natl Acad Sci U S A. 2014 doi: 10.1073/pnas.1406611111.

Pontvianne F et al., (2013) Subnuclear partitioning of rRNA genes between the nucleolus and nucleoplasm reflects alternative epiallelic states. Genes Dev. doi: 10.1101/gad.221648.113.

Moissiard G et al., (2012) MORC family ATPases required for heterochromatin condensation and gene silencing. Science. doi: 10.1126/science.1221472.

Funding:

  • CNRS
  • University of Perpignan (UPVD)
  • Agence National de Recherche (ANR)
  • Publications :

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News

Seminar Tuesday May 21rst, 11 am, salle de séminaires du LGDP, given by Julia MORALES, Laboratoire de Biologie Intégrative des Modèles Marins, UMR 8227 CNRS/Sorbonne Université, Station Biologique de Roscoff. Title : "Translational control after fertilization in sea urchin."

 

 

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