An eRNA transcription checkpoint for diverse signal-dependent enhancer activation programs

Area of Science:

• Molecular Biology
• Gene Regulation
• Biochemistry

Background:

• Signal and ligand-dependent pathways activate regulatory enhancer programs.
• A conserved 'checkpoint' strategy is suggested to underlie enhancer activation.
• Understanding this mechanism is key to deciphering gene expression control.

Purpose of the Study:

• To identify a common molecular mechanism for signal- and ligand-dependent enhancer activation.
• To investigate the role of enhancer RNA (eRNA) transcription checkpoints.
• To elucidate how diverse signaling pathways converge on enhancer regulation.

Main Methods:

• Investigated the recruitment of DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-phosphorylated KAP1.
• Analyzed the inhibition of KAP1 association with 7SK and SUMO ligase activity on CDK9.
• Studied the formation of activated positive transcription elongation factor b (P-TEFb) complexes.

Main Results:

• A shared enhancer RNA (eRNA) transcription checkpoint is released.
• DNA-PKcs-phosphorylated KAP1 acts as a modulator, inhibiting interactions with 7SK and SUMO ligase on CDK9.
• This facilitates P-TEFb activation, enabling eRNA elongation in pathways like estrogen receptor-α, NF-κB, androgen receptor, and neuronal depolarization.

Conclusions:

• A conserved molecular mechanism involving a P-TEFb-associated checkpoint regulates diverse signal-dependent enhancers.
• This checkpoint release is essential for converting basal enhancers to an active state.
• The findings reveal a common strategy employed by critical regulatory enhancers to mediate endocrine and paracrine signaling.