Translin-associated factor X is post-transcriptionally regulated by its partner protein TB-RBP, and both are essential for normal cell proliferation

J Biol Chem. 2004 Mar 26;279(13):12605-14. doi: 10.1074/jbc.M313133200. Epub 2004 Jan 7.

Abstract

To determine the functions of the DNA/RNA-binding protein TB-RBP in somatic cells, we examined cultured primary mouse embryonic fibroblasts (MEFs) derived from TB-RBP-deficient mice. The TB-RBP-deficient MEFs exhibit a reduced growth rate compared with MEFs from littermates. Reintroduction of TB-RBP remedies this defect. A partner protein of TB-RBP, Translin-associated factor X (TRAX), was absent in TB-RBP-deficient MEFs, despite normal TRAX mRNA levels. TRAX is dependent upon the presence of TB-RBP and is removed from null MEFs following ubiquitination. Re-introduction of TB-RBP, but not TB-RBP lacking an oligomerization domain, into null MEFs stabilized TRAX protein without changing TRAX mRNA levels. The coordinated expression of TB-RBP and TRAX is also seen in synchronized cells, where the amount of TRAX protein but not TRAX RNA closely parallels TB-RBP levels throughout the cell cycle. In transgenic mice overexpressing TRAX in testis, total TB-RBP and TRAX levels are constant with reductions of endogenous TRAX compensating for exogenous TRAX. Using RNA interference, reductions of either TB-RBP or TRAX (without affecting TB-RBP) slow cell growth rates. We conclude that TRAX is post-transcriptionally stabilized by TB-RBP and both proteins are needed for normal cell proliferation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Northern
  • Blotting, Western
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / chemistry*
  • Carrier Proteins / physiology*
  • Cell Cycle
  • Cell Division
  • Cells, Cultured
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / physiology*
  • Dose-Response Relationship, Drug
  • Embryo, Mammalian / cytology
  • Fibroblasts / metabolism
  • Flow Cytometry
  • HeLa Cells
  • Heterozygote
  • Humans
  • Kinetics
  • Leucine / chemistry
  • Mice
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • NIH 3T3 Cells
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / physiology*
  • Plasmids / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA Interference
  • RNA Processing, Post-Transcriptional*
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins
  • Time Factors
  • Transfection
  • Transgenes
  • Ubiquitin / chemistry
  • Ubiquitin / metabolism

Substances

  • Carrier Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • TSN protein, human
  • TSNAX protein, human
  • Tsn protein, mouse
  • Tsnax protein, mouse
  • Ubiquitin
  • Leucine