Interaction profiling identifies the human nuclear exosome targeting complex

Mol Cell. 2011 Aug 19;43(4):624-37. doi: 10.1016/j.molcel.2011.06.028.

Abstract

The RNA exosome is a conserved degradation machinery, which obtains full activity only when associated with cofactors. The most prominent activator of the yeast nuclear exosome is the RNA helicase Mtr4p, acting in the context of the Trf4p/Air2p/Mtr4p polyadenylation (TRAMP) complex. The existence of a similar activator(s) in humans remains elusive. By establishing an interaction network of the human nuclear exosome, we identify the trimeric Nuclear Exosome Targeting (NEXT) complex, containing hMTR4, the Zn-knuckle protein ZCCHC8, and the putative RNA binding protein RBM7. ZCCHC8 and RBM7 are excluded from nucleoli, and consistently NEXT is specifically required for the exosomal degradation of promoter upstream transcripts (PROMPTs). We also detect putative homolog TRAMP subunits hTRF4-2 (Trf4p) and ZCCHC7 (Air2p) in hRRP6 and hMTR4 precipitates. However, at least ZCCHC7 function is restricted to nucleoli. Our results suggest that human nuclear exosome degradation pathways comprise modules of spatially organized cofactors that diverge from the yeast model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carrier Proteins / analysis
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Cell Nucleolus / enzymology
  • Cell Nucleolus / metabolism
  • Chromosomal Proteins, Non-Histone / analysis
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA-Directed DNA Polymerase / analysis
  • DNA-Directed DNA Polymerase / metabolism
  • Exoribonucleases / analysis
  • Exoribonucleases / metabolism
  • Exoribonucleases / physiology
  • Exosome Multienzyme Ribonuclease Complex
  • Humans
  • Models, Biological*
  • Nuclear Proteins / analysis
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / physiology*
  • RNA Helicases / analysis
  • RNA Helicases / metabolism
  • RNA Helicases / physiology*
  • RNA-Binding Proteins / analysis
  • RNA-Binding Proteins / metabolism
  • RNA-Binding Proteins / physiology*
  • Ribonucleases / metabolism*
  • Transcription Factors / analysis
  • Transcription Factors / metabolism

Substances

  • Carrier Proteins
  • Chromosomal Proteins, Non-Histone
  • Nuclear Proteins
  • RBM7 protein, human
  • RBM8A protein, human
  • RNA-Binding Proteins
  • Transcription Factors
  • ZCCHC7 protein, human
  • ZCCHC8 protein, human
  • DNA-Directed DNA Polymerase
  • PAPD7 protein, human
  • Exoribonucleases
  • Exosome Multienzyme Ribonuclease Complex
  • Ribonucleases
  • EXOSC10 protein, human
  • SKIV2L2 protein, human
  • RNA Helicases