Model of the control of an epigenetically repressed gene by a distal transcriptional enhancer. A gene indicated by an arrow at its transcription start site is located in a compacted chromatin domain and transcriptionally inactive. Chromatin compaction is initiated by protein complexes that methylate histones (small red circles), which leads to the recruitment of proteins (pink circles) that compact the chromatin structure (indicated as blue cloud). A transcriptional enhancer is found outside of the repressed chromatin domain. The enhancer is susceptible to signal I, which could act via an environmentally or developmentally controlled transcription factor (TF). Open chromatin at the transcriptional enhancer could be maintained by the activity of histone acetylases (small and large purple circles). Upon perception of signal I , the enhancer can extrude the promoter and transcriptional start site of the repressive chromatin domain. This allows the assembly of the transcription pre-initiation complex and the binding of transcription factors that are associated with signal II, leading to transcription initiation.
Model of the control of an epigenetically repressed gene by a distal transcriptional enhancer. A gene indicated by an arrow at its transcription start site is located in a compacted chromatin domain and transcriptionally inactive. Chromatin compaction is initiated by protein complexes that methylate histones (small red circles), which leads to the recruitment of proteins (pink circles) that compact the chromatin structure (indicated as blue cloud). A transcriptional enhancer is found outside of the repressed chromatin domain. The enhancer is susceptible to signal I, which could act via an environmentally or developmentally controlled transcription factor (TF). Open chromatin at the transcriptional enhancer could be maintained by the activity of histone acetylases (small and large purple circles). Upon perception of signal I , the enhancer can extrude the promoter and transcriptional start site of the repressive chromatin domain. This allows the assembly of the transcription pre-initiation complex and the binding of transcription factors that are associated with signal II, leading to transcription initiation.
Plant genes can acquire a memory which defines their expression state based on past experience. By stabilizing an expression state for future reference, this epigenetic memory determines how strongly, or if at all, genes will respond to current environmental and developmental cues. Gene memories are mechanistically linked to the packaging of nuclear DNA into a protein-containing chromatin structure; in particular, tight packaging of chromatin will freeze underlying genes in a repressed state (see figure). Short stretches of so-called open chromatin regions can be maintained within longer regions of tightly packaged chromatin. These regions represent windows of communication to regulatory factors and often coincide with transcriptional enhancers that can be able to erase the repressive memory of associated genes.
Our group is interested in the interplay of transcription factors and chromatin in gene regulation.