Microspherule protein 1, Mi-2beta, and RET finger protein associate in the nucleolus and up-regulate ribosomal gene transcription.
The nucleolus is the site of ribosomal DNA (rDNA) transcription and ribosome production. In exploring the role of nucleolar protein MCRS1 (microspherule protein1)/MSP58 (58-kDa microspherule protein), we found that Mi-2beta, a component of a nucleosome remodeling and deacetylase (NuRD) complex, RET finger protein (RFP), and upstream binding factor (UBF) were associated with MCRS1. Yeast two-hybrid assays revealed that MCRS1 bound to the ATPase/helicase region of Mi-2beta and the coiled-coil region of RFP. Interestingly, confocal microscopic analyses revealed the co-localization of MCRS1, Mi-2beta, RFP, and the rRNA transcription factor UBF in the nucleoli. We also found that MCRS1, Mi-2beta, and RFP were associated with rDNA using a chromatin immunoprecipitation assay. Finally, we showed that MCRS1, Mi-2beta, and RFP up-regulated transcriptional activity of the rDNA promoter and that ribosomal RNA transcription was repressed when MCRS1, Mi-2beta, and RFP expression was reduced using siRNA. These results indicated that Mi-2beta and RFP, known to be involved in transcriptional repression in the nucleus, co-localize with MCRS1 in the nucleolus and appear to activate the rRNA transcription.
Shimono
Keiko
K
Department of Pathology, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
Shimono
Yohei
Y
Shimokata
Kaoru
K
Ishiguro
Naoki
N
Takahashi
Masahide
M
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001324:Autoantigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D015854:Up-Regulation; D000070584:Tripartite Motif Proteins
D000251:Adenosine Triphosphatases; D001324:Autoantigens; D004265:DNA Helicases; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C115323:CHD4 protein, human; C113292:MCRS1 protein, human; C064419:TRIM27 protein, human; D000070584:Tripartite Motif Proteins