To regulate transcription, chromatin factors impact the activities of promoters and enhancers. An essential step for understanding the transcriptional circuits that control development is the identification and characterization of these regulatory elements. We generated the first map of regulatory elements across the development and ageing of an animal, identifying 42,245 elements accessible in at least one C. elegans stage (Janes et al, 2018). We defined 15,714 protein-coding promoters and 19,231 putative enhancers, and found that that both types of element can drive orientation-independent transcription. Additionally, over 1000 promoters produce transcripts antisense to protein coding genes, suggesting involvement in a widespread regulatory mechanism. The accessibility of most elements changes during development and/or ageing and patterns of accessibility change are linked to specific developmental or physiological processes. We analyse the function and regulation of enhancers, promoters, and non-coding transcription using transgenic and genome editing approaches.
