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The role of Mediator and Little Elongation Complex in transcription termination

Hidehisa Takahashi1, Amol Ranjan2, Shiyuan Chen2

  • 1Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa, 216-0004, Japan. hide0213@yokohama-cu.ac.jp.

Nature Communications
|February 28, 2020
PubMed

Insights

Human Mediator subunit MED26 recruits the Little Elongation Complex (LEC) to control transcription termination for non-polyadenylated transcripts, including snRNAs and histone mRNAs, at Cajal bodies.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • Biochemistry

Background:

  • The Mediator complex is crucial for RNA Polymerase II transcription.
  • MED26, a human Mediator subunit, was previously shown to recruit the Super Elongation Complex (SEC) or Little Elongation Complex (LEC).
  • The precise mechanisms by which MED26 engages SEC or LEC for distinct gene regulation remained unclear.

Purpose of the Study:

  • To elucidate the role of MED26 in recruiting LEC.
  • To investigate how MED26-recruited LEC modulates transcription termination.
  • To understand the involvement of MED26-LEC interactions in processing non-polyadenylated transcripts.

Main Methods:

  • Investigated MED26's interaction with LEC.
  • Analyzed transcription termination of snRNA and RDH genes.
  • Examined interactions with transcription factors like CBC-ARS2, NELF/DSIF, Integrator, and Heat Labile Factor.

Main Results:

  • MED26 recruits LEC to Cajal bodies to regulate transcription termination of non-polyadenylated transcripts (snRNAs, RDH mRNAs).
  • LEC, recruited by MED26, enhances Pol II transcription termination via interaction with CBC-ARS2 and NELF/DSIF.
  • MED26-recruited LEC promotes 3' end processing by recruiting Integrator or Heat Labile Factor for snRNA or RDH genes, respectively.

Conclusions:

  • MED26 plays a key role in transcription termination of specific non-polyadenylated RNAs through LEC recruitment.
  • This mechanism involves interactions with multiple transcription and processing factors at Cajal bodies.
  • Findings reveal a novel function of MED26 in precise gene expression regulation.

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