Nucleophosmin/B23 regulates ubiquitin dynamics in nucleoli by recruiting deubiquitylating enzyme USP36.
The nucleolus is a subnuclear compartment with multiple cellular functions, including ribosome biogenesis. USP36 is a deubiquitylating enzyme that localizes to nucleoli and plays an essential role in regulating the structure and function of the organelle. However, how the localization of USP36 is regulated remains unknown. Here, we identified a short stretch of basic amino acids (RGKEKKIKKFKREKRR) that resides in the C-terminal region of USP36 and serves as a nucleolar localization signal for the protein. We found that this motif interacts with a central acidic region of nucleophosmin/B23, a major nucleolar protein involved in various nucleolar functions. Knockdown of nucleophosmin/B23 resulted in a significant reduction in the amount of USP36 in nucleoli, without affecting the cellular USP36 level. This was associated with elevated ubiquitylation levels of fibrillarin, a USP36 substrate protein in nucleoli. We conclude that nucleophosmin/B23 recruits USP36 to nucleoli, thereby serving as a platform for the regulation of nucleolar protein functions through ubiquitylation/deubiquitylation.
Endo
Akinori
A
Department of Biological Sciences, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Kitamura
Naomi
N
Department of Biological Sciences, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Komada
Masayuki
M
Department of Biological Sciences, Tokyo Institute of Technology, Yokohama 226-8501, Japan. Electronic address: makomada@bio.titech.ac.jp.
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002466:Cell Nucleolus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C501066:USP36 protein, human; D025801:Ubiquitin; D000090243:Nucleophosmin; D043222:Ubiquitin Thiolesterase
Nat Rev Mol Cell Biol. 2007 Jul;8(7):574-85
17519961
Mol Cell Biol. 2005 Feb;25(4):1258-71
15684379
J Cell Biol. 2008 Nov 17;183(4):589-95
19015314
Biochemistry. 1996 Feb 27;35(8):2668-73
8611572
EMBO Rep. 2009 Mar;10(3):231-8
19229283
Mol Biol Cell. 2002 Oct;13(10):3576-87
12388758
Genes Dev. 2004 Aug 1;18(15):1862-74
15289458
Mol Cell Biol. 2008 Dec;28(23):7050-65
18809582
J Biol Chem. 2004 Jun 18;279(25):26563-70
15060081
EMBO Rep. 2008 Mar;9(3):273-9
18259216
Curr Biol. 2007 May 1;17(9):749-60
17446074
Nucleic Acids Res. 1998 Oct 1;26(19):4508-15
9742256
Nature. 2005 Jan 6;433(7021):77-83
15635413
PLoS One. 2007 Jul 25;2(7):e679
17653289
Mol Cell Biol. 2004 Feb;24(3):985-96
14729947
Mol Cell Biol. 2006 Jul;26(13):5131-45
16782897
Mol Cell. 2003 Nov;12(5):1151-64
14636574
Nat Rev Cancer. 2006 Jul;6(7):493-505
16794633
Mol Cell Biol. 2000 Apr;20(7):2517-28
10713175
J Cell Sci. 2009 Mar 1;122(Pt 5):678-86
19208757
Cell. 2005 Dec 2;123(5):773-86
16325574
J Biol Chem. 1993 Jul 5;268(19):13930-4
8314759
Protein Sci. 1999 Apr;8(4):905-12
10211837