Chtop Is a Component of the Dynamic TREX mRNA Export Complex

EMBO J. 2013 Feb 6;32(3):473-86. doi: 10.1038/emboj.2012.342. Epub 2013 Jan 8.

Abstract

The TREX complex couples nuclear pre-mRNA processing with mRNA export and contains multiple protein components, including Uap56, Alyref, Cip29 and the multi-subunit THO complex. Here, we have identified Chtop as a novel TREX component. We show that both Chtop and Alyref activate the ATPase and RNA helicase activities of Uap56 and that Uap56 functions to recruit both Alyref and Chtop onto mRNA. As observed with the THO complex subunit Thoc5, Chtop binds to the NTF2-like domain of Nxf1, and this interaction requires arginine methylation of Chtop. Using RNAi, we show that co-knockdown of Alyref and Chtop results in a potent mRNA export block. Chtop binds to Uap56 in a mutually exclusive manner with Alyref, and Chtop binds to Nxf1 in a mutually exclusive manner with Thoc5. However, Chtop, Thoc5 and Nxf1 exist in a single complex in vivo. Together, our data indicate that TREX and Nxf1 undergo dynamic remodelling, driven by the ATPase cycle of Uap56 and post-translational modifications of Chtop.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • DEAD-box RNA Helicases / metabolism
  • DNA Methylation
  • DNA Primers / genetics
  • Exodeoxyribonucleases / metabolism*
  • Genetic Complementation Test
  • Humans
  • In Situ Hybridization, Fluorescence
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphoproteins / metabolism*
  • RNA Interference
  • RNA Processing, Post-Transcriptional / physiology*
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • ALYREF protein, human
  • CHTOP protein, human
  • DNA Primers
  • Multiprotein Complexes
  • Nuclear Proteins
  • Phosphoproteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • SARNP protein, human
  • Transcription Factors
  • Exodeoxyribonucleases
  • three prime repair exonuclease 1
  • DDX39B protein, human
  • DEAD-box RNA Helicases