<p>The evidence that signal- and ligand-dependent pathways function by activating regulatory enhancer programs suggests that a ‘checkpoint’ strategy may underline activation of many diversely regulated enhancers. Here we report a molecular mechanism common to several acute signal- and ligand-dependent enhancer activation programs based on release of a shared enhancer RNA (eRNA) transcription checkpoint. It requires recruitment of a DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-phosphorylated RING finger repressor (Krüppel-associated box)-associated protein 1 (KAP1) as a modulator, inhibiting its association with 7SK and E3 small ubiquitin-like modifier (SUMO) ligase activity on the CDK9 subunit of positive transcription elongation factor b (P-TEFb). This facilitates formation of an activated P-TEFb complex, licensing eRNA elongation. Overcoming this checkpoint for signal-dependent enhancer activation occurs in diverse pathways, including estrogen receptor-α, NF-κB-regulated proinflammatory stimulation, androgen receptor and neuronal depolarization. Therefore, a specific strategy required to convert a basal state enhancer P-TEFb complex to an active state to release a conserved checkpoint is apparently employed by several functionally important signal-regulated regulatory enhancers to implement the instructions of the endocrine and paracrine system.</p>

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

  • Lishuan Wang,
  • Wei Yuan,
  • Amir Gamliel,
  • Wubin Ma,
  • Seowon Lee,
  • Yuliang Tan,
  • Zeyu Chen,
  • Havilah Taylor,
  • Kenneth Ohgi,
  • Soohwan Oh,
  • Aneel K. Aggarwal,
  • Michael G. Rosenfeld

摘要

The evidence that signal- and ligand-dependent pathways function by activating regulatory enhancer programs suggests that a ‘checkpoint’ strategy may underline activation of many diversely regulated enhancers. Here we report a molecular mechanism common to several acute signal- and ligand-dependent enhancer activation programs based on release of a shared enhancer RNA (eRNA) transcription checkpoint. It requires recruitment of a DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-phosphorylated RING finger repressor (Krüppel-associated box)-associated protein 1 (KAP1) as a modulator, inhibiting its association with 7SK and E3 small ubiquitin-like modifier (SUMO) ligase activity on the CDK9 subunit of positive transcription elongation factor b (P-TEFb). This facilitates formation of an activated P-TEFb complex, licensing eRNA elongation. Overcoming this checkpoint for signal-dependent enhancer activation occurs in diverse pathways, including estrogen receptor-α, NF-κB-regulated proinflammatory stimulation, androgen receptor and neuronal depolarization. Therefore, a specific strategy required to convert a basal state enhancer P-TEFb complex to an active state to release a conserved checkpoint is apparently employed by several functionally important signal-regulated regulatory enhancers to implement the instructions of the endocrine and paracrine system.