TY - JOUR
T1 - Functional inactivation of the mouse nucleolar protein Bop1 inhibits multiple steps in pre-rRNA processing and blocks cell cycle progression
AU - Strezoska, Zaklina
AU - Pestov, Dimitri G.
AU - Lau, Lester F.
PY - 2002/8/16
Y1 - 2002/8/16
N2 - Bop1 is a conserved nucleolar protein involved in rRNA processing and ribosome assembly in eukaryotes. Expression of its dominant-negative mutant bop1Δ in mouse cells blocks rRNA maturation and synthesis of large ribosomal subunits and induces a reversible, p53-dependent cell cycle arrest. In this study, we have conducted a deletion analysis of Bop1 and identified a new mutant, Bop1N2, that also acts as a potent inhibitor of cell cycle progression. Bop1N2 and bop1Δ are C-terminal and N-terminal deletion mutants, respectively, and share only 72 amino acid residues. Both mutant proteins are localized to the nucleolus and strongly inhibit rRNA processing, suggesting that activation of a cell cycle checkpoint by Bop1 mutants is linked to their inhibitory effects on rRNA and ribosome synthesis. By using these dominant-negative mutants as well as antisense oligonucleotides to interfere with endogenous Bop1, we identified specific rRNA processing steps that require Bop1 function in mammalian cells. Our data demonstrate that Bop1 is required for proper processing at four distinct sites located within the internal transcribed spacers ITS1 and ITS2 and the 3′ external spacer. We propose a model in which Bop1 serves as an essential factor in ribosome formation that coordinates processing of the spacer regions in pre-rRNA.
AB - Bop1 is a conserved nucleolar protein involved in rRNA processing and ribosome assembly in eukaryotes. Expression of its dominant-negative mutant bop1Δ in mouse cells blocks rRNA maturation and synthesis of large ribosomal subunits and induces a reversible, p53-dependent cell cycle arrest. In this study, we have conducted a deletion analysis of Bop1 and identified a new mutant, Bop1N2, that also acts as a potent inhibitor of cell cycle progression. Bop1N2 and bop1Δ are C-terminal and N-terminal deletion mutants, respectively, and share only 72 amino acid residues. Both mutant proteins are localized to the nucleolus and strongly inhibit rRNA processing, suggesting that activation of a cell cycle checkpoint by Bop1 mutants is linked to their inhibitory effects on rRNA and ribosome synthesis. By using these dominant-negative mutants as well as antisense oligonucleotides to interfere with endogenous Bop1, we identified specific rRNA processing steps that require Bop1 function in mammalian cells. Our data demonstrate that Bop1 is required for proper processing at four distinct sites located within the internal transcribed spacers ITS1 and ITS2 and the 3′ external spacer. We propose a model in which Bop1 serves as an essential factor in ribosome formation that coordinates processing of the spacer regions in pre-rRNA.
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U2 - 10.1074/jbc.M204381200
DO - 10.1074/jbc.M204381200
M3 - Article
C2 - 12048210
AN - SCOPUS:0037119468
SN - 0021-9258
VL - 277
SP - 29617
EP - 29625
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 33
ER -