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Updated: Aug 7, 2026
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Repressing Gene Transcription by Redirecting Cellular Machinery with Chemical Epigenetic Modifiers
Published on: September 20, 2018
Structure of human cytoplasmic Pol II complex explains global transcription repression by GDOWN1
Jana Schmitzová1, Yumeng Zhan1, Srinivasan Rengachari1,2
1Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
Nature Communications
|August 5, 2026
Summary
RNA polymerase II (Pol II) is fully assembled in the cytoplasm before nuclear import, bound by assembly factors like GDOWN1. GDOWN1 binding inactivates Pol II, suggesting a role in regulating transcription.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- RNA polymerase II (Pol II) is essential for gene transcription.
- The cytoplasmic assembly, nuclear import, and function of Pol II assembly factors are not well understood.
Purpose of the Study:
- To investigate the cytoplasmic assembly and regulation of RNA polymerase II.
- To elucidate the role of GDOWN1 in Pol II assembly, import, and function.
Main Methods:
- Isolation of cytoplasmic RNA polymerase II (cfPol II) from human cells.
- Cryo-electron microscopy (Cryo-EM) analysis of cfPol II structure.
- Biochemical assays to study GDOWN1 interactions and function.
Main Results:
- Pol II is fully assembled in the cytoplasm associated with factors including GDOWN1, RPAP2, GPN1, and GPN3.
- Cryo-EM revealed RPAP2 and GDOWN1 bound to assembled Pol II.
- GDOWN1 facilitates the soluble expression of a Pol II subcomplex and inhibits Pol II activity by blocking transcription factor binding sites.
Conclusions:
- GDOWN1 plays a role in RNA polymerase II assembly and cytoplasmic retention.
- GDOWN1 binding to Pol II inhibits its transcriptional activity, suggesting a mechanism for global transcription repression.
- A model is proposed for GDOWN1's role in Pol II assembly, nuclear import, and transcription regulation.
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