MED25 Promotes Enhancer-Promoter Looping during Jasmonate Signaling

MED25 Promotes Enhancer-Promoter Looping during Jasmonate Signaling

It has been shown in animal models that enhancers communicate with target promoters by recruiting transcription factors and their co-factors, which establish enhancer-promoter chromatin looping. The signal-dependent chromatin looping is essential for correct spatio-temporal transcriptional programming. However, systematic identification of enhancers engaged in specific physiological processes or hormone signaling pathways of higher plants is still lacking.

Recently, a research  team revealed a number of new insights into the regulation of JA-responsive gene expression by enhancers.

The researchers profiled the occupancy pattern of the master regulator MYC2 (a bHLH transcription factor) and its coactivator mediator complex subunit 25 (MED25) in JA signaling by ChIP-Seq analysis. By this approach, they identified JA Enhancers (JAEs) specifically involved in JA signaling.

The results show that JA regulates the dynamic chromatin looping between JAEs and their promoters in a MED25 dependent manner. They also found that MYC2 autoregulates itself by JAEs.

Interestingly, the JAE of the MYC2 locus named ME2 positively regulates MYC2 expression during short-term JA responses but negatively regulates MYC2 expression during constant JA responses.

These results published in Nature Plants discovered the regulatory control of gene transcription in JA signaling by enhancers. This study provides a paradigm for future study of enhancers in specific physiological processes of plant.

They also exemplify that new gene editing tools, such as CRISPR/Cas9, open up new avenues to elucidate the in vivo function of enhancers.