Rapid and pervasive changes in genome-wide enhancer usage during mammalian development

Area of Science:

• Genomics
• Developmental Biology
• Epigenetics

Background:

• Enhancers are crucial for tissue-specific gene expression, yet their dynamic activity during development is poorly understood.
• Genome-wide enhancer annotation is advancing, but temporal patterns and in vivo roles remain largely unexplored.

Purpose of the Study:

• To investigate the genome-wide utilization and temporal activity of enhancers during mammalian development.
• To understand the functional roles of dynamic enhancer usage in different tissues and developmental stages.

Main Methods:

• Utilized epigenomic profiling (H3K27ac) to identify active enhancers.
• Employed transgenic mouse assays to examine enhancer activity across seven developmental stages in three tissues.
• Performed comparative genomic analysis to assess evolutionary conservation.

Main Results:

• Identified approximately 90,000 enhancers with tightly temporally restricted activity windows.
• Found that enhancers are associated with stage-specific biological functions and regulatory pathways.
• Observed a decrease in evolutionary conservation of enhancers after midgestation.

Conclusions:

• Enhancer usage is highly dynamic and temporally regulated during mammalian development.
• These dynamic changes in enhancer activity are fundamental to developmental processes and disease.
• The study provides a genome-wide view of temporal enhancer dynamics in vivo.