Enhancer dependence of cell-type-specific gene expression increases with developmental age.

Area of Science:

• Developmental Biology
• Epigenetics
• Genomics

Background:

• Cell-type-specific gene regulation is crucial for development but how its logic changes over time is poorly understood.
• Understanding ontogenetic shifts in gene regulation provides insights into developmental processes and cellular identity.

Purpose of the Study:

• To investigate changes in gene regulatory principles between embryonic and adult erythroblasts.
• To compare transcriptomic, epigenomic, and 3D genomic profiles across developmental stages.

Main Methods:

• Comparative analysis of transcriptomic, epigenomic, and 3D genomic data from embryonic (EryP) and adult (EryD) erythroblasts.
• Chromatin accessibility assays, ChIP-seq (H3K27ac, Gata1, Myb), HiChIP (Gata1), and genome editing.
• Development of a metric for enhancer dependence of transcription.

Main Results:

• Adult erythroblasts show reduced chromatin accessibility but enriched distal regulatory element activity (H3K27ac, Gata1, Myb).
• Embryonic cells exhibit promoter-centric regulation (Gata1), while adult cells increasingly rely on distal enhancers (Myb-mediated activation).
• Enhancer-promoter interactions increase with age, and distal enhancers become essential for gene expression in adult cells.

Conclusions:

• Fundamental, conserved differences exist in gene regulation logic between embryonic and adult cells.
• Embryonic gene regulation is simpler and promoter-centric, whereas adult cells utilize more complex, enhancer-driven combinatorial control.
• A progressive reliance on cell-specific enhancers with increasing ontogenetic age is observed across diverse tissues.