Translin-associated factor X is post-transcriptionally regulated by its partner protein TB-RBP, and both are essential for normal cell proliferation.
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.
Yang
Shicheng
S
Center for Research on Reproduction and Women's Health, University of Pennsylvania School of Medicine, 1310 Biomedical Research Building II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6142, USA.
Cho
Yoon Shin
YS
Chennathukuzhi
Vargheese M
VM
Underkoffler
Lara A
LA
Loomes
Kathleen
K
Hecht
Norman B
NB
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology*; D002453:Cell Cycle; D002455:Cell Division; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D006367:HeLa Cells; D006579:Heterozygote; D006801:Humans; D007700:Kinetics; D007930:Leucine / Q000737:chemistry; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D013997:Time Factors; D014162:Transfection; D019076:Transgenes; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C095563:TSN protein, human; C498305:TSNAX protein, human; C498303:Tsn protein, mouse; C498306:Tsnax protein, mouse; D025801:Ubiquitin; D007930:Leucine