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Ribosomal stress induces processing of Mybbp1a and its translocation from the nucleolus to the nucleoplasm
Author(s) -
Yamauchi Tomohiro,
Keough Rebecca A.,
Gonda Thomas J.,
Ishii Shunsuke
Publication year - 2008
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2007.01148.x
Subject(s) - ribosome biogenesis , nucleolin , nucleoplasm , nucleolus , biology , nucleophosmin , ribosomal protein , ribosome , microbiology and biotechnology , transcription (linguistics) , rna , genetics , cytoplasm , gene , linguistics , philosophy
Myb‐binding protein 1a (Mybbp1a) was originally identified as a c‐ myb proto‐oncogene product (c‐Myb)‐interacting protein, and also binds to various other transcription factors. The 160‐kDa Mybbp1a protein (p160 MBP ) is ubiquitously expressed and is post‐translationally processed in some types of cells to generate an amino‐terminal 67 kDa fragment (p67 MBP ). Despite its interaction with various transcription factors, Mybbp1a is localized predominantly, but not exclusively, in nucleoli. Here, we have purified the two Mybbp1a‐containing complexes. The smaller complex contained p67 MBP and p140 MBP , which lacked the C‐terminal region of p160 MBP containing the nucleolar localization sequences. The larger complex contained the intact p160 MBP and various ribosomal subunits. Treatment of cells with actinomycin D (ActD), cisplatin or UV, all of which inhibit ribosome biogenesis, induced processing of p160 MBP into p140 MBP and p67 MBP . ActD, cisplatin and UV also induced a translocation of Mybbp1a from the nucleolus to the nucleoplasm. Both small and large Mybbp1a complexes contained nucleophosmin and nucleolin. In contrast, nucleostemin was detected only in the large complex, while the cell cycle‐regulated protein EBP1 was only in the small complex. These results suggest that Mybbp1a may connect the ribosome biogenesis and the Myb‐dependent transcription, which controls cell cycle progression and proliferation.