Epigenetic Mechanisms and Chromatin Architecture

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

Epigenetic Mechanisms and Chromatin Architecture

TEAM :

DESCOMBIN Julie - IGE UPVD

DIOP Khadidiatou - Doctorante

JARRY Lucas - Doctorant

MOISSIARD Guillaume - Chercheur CNRS

PICAULT Nathalie - Maître de conférences UPVD

PONTVIANNE Frédéric - Chercheur CNRS

Scientific context:

In eukaryotes, the genetic material is precisely organized in the nucleus as chromatin 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), and RNA molecules. DNA methylation and histone modifications are important epigenetic marks regulating gene transcription and repressing DNA repeats, such as transposable elements (TEs) (Kouzarides, 2007; Grewal, 2007). These epigenetic marks also define the compaction state of chromatin. Heterochromatin, which is predominantly composed of DNA repeats and TEs, is highly condensed and transcriptionally repressed. Conversely, euchromatin, which is more relaxed, is enriched in genes that are more permissive to transcription.

Research projects:

We are currently investigating the cellular and molecular mechanisms that are involved in the subnuclear organization of chromatin, together with the epigenetic pathways that regulate gene expression and repress TEs. We study these different mechanisms using mainly Arabidopsis thaliana as model plant, grown under normal physiological conditions or in response to environmental stimuli (heat, light, pathogens…).

In further details, we aim at:

1. Mapping the chromatin regions in contact with the nucleolus.
2. Understanding the epigenome subnuclear organization and the impact of gene positioning on transcriptional regulation.
3. Deciphering the role of epigenetic factors in the regulation of gene expression.
4. Understanding heat stress-induced epigenetic processes.
5. Developing unbiased forward genetic approaches to identify new epigenetic factors.

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, confocal microscopic and Fluorescence-activated cell sorting (FACS) approaches allow us to study nuclear organization at the cellular level.

Funding:

• CNRS
• University of Perpignan (UPVD)
• Agence National de Recherche (ANR)
• TULIP LabEx
• GDR EPIPLANT
• eCOST INDEPTH

Publications :