title: RINT-1 interacts with MSP58 within nucleoli and plays a role in ribosomal gene transcription.
abstract: The nucleolus is the cellular site of ribosomal (r)DNA transcription and ribosome biogenesis. The 58-kDa microspherule protein (MSP58) is a nucleolar protein involved in rDNA transcription and cell proliferation. However, regulation of MSP58-mediated rDNA transcription remains unknown. Using a yeast two-hybrid system with MSP58 as bait, we isolated complementary (c)DNA encoding Rad50-interacting protein 1 (RINT-1), as a MSP58-binding protein. RINT-1 was implicated in the cell cycle checkpoint, membrane trafficking, Golgi apparatus and centrosome dynamic integrity, and telomere length control. Both in vitro and in vivo interaction assays showed that MSP58 directly interacts with RINT-1. Interestingly, microscopic studies revealed the co-localization of MSP58, RINT-1, and the upstream binding factor (UBF), a rRNA transcription factor, in the nucleolus. We showed that ectopic expression of MSP58 or RINT-1 resulted in decreased rRNA expression and rDNA promoter activity, whereas knockdown of MSP58 or RINT-1 by siRNA exerted the opposite effect. Coexpression of MSP58 and RINT-1 robustly decreased rRNA synthesis compared to overexpression of either protein alone, whereas depletion of RINT-1 from MSP58-transfected cells enhanced rRNA synthesis. We also found that MSP58, RINT-1, and the UBF were associated with the rDNA promoter using a chromatin immunoprecipitation assay. Because aberrant ribosome biogenesis contributes to neoplastic transformation, our results revealed a novel protein complex involved in the regulation of rRNA gene expression, suggesting a role for MSP58 and RINT-1 in cancer development.
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC.
authors.forename: Chuan-Pin
authors.initials: CP
authors.lastname: Yang
authors.affiliation: Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, 40201, Taiwan, ROC; Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, 40201, Taiwan, ROC.
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Kuo
authors.affiliation: Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, 11031, Taiwan, ROC.
authors.forename: Yi-Chao
authors.initials: YC
authors.lastname: Lee
authors.affiliation: Institute for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, 11031, Taiwan, ROC.
authors.forename: Kuen-Haur
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Infectious Diseases and Signaling Research Center, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan, ROC.
authors.forename: Chi-Wu
authors.initials: CW
authors.lastname: Chiang
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Infectious Diseases and Signaling Research Center, National Cheng Kung University, Tainan, 70101, Taiwan, ROC.
authors.forename: Ju-Ming
authors.initials: JM
authors.lastname: Wang
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC.
authors.forename: Che-Chia
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Infectious Diseases and Signaling Research Center, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, 11031, Taiwan, ROC; Center for Neurotrauma and Neuroregeneration, Taipei Medical University, Taipei, 11031, Taiwan, ROC. Electronic address: wcchang@mail.ncku.edu.tw.
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Infectious Diseases and Signaling Research Center, National Cheng Kung University, Tainan, 70101, Taiwan, ROC; Institute for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, 11031, Taiwan, ROC. Electronic address: lindy@mail.ncku.edu.tw.
authors.forename: Ding-Yen
authors.initials: DY
authors.lastname: Lin
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002458:Cell Fractionation; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D001678:Organelle Biogenesis; D035463:Pol1 Transcription Initiation Complex Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D018797:Cell Cycle Proteins; D004275:DNA, Ribosomal; C113292:MCRS1 protein, human; D009687:Nuclear Proteins; D035463:Pol1 Transcription Initiation Complex Proteins; C422909:RINT1 protein, human; D012335:RNA, Ribosomal; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C063844:transcription factor UBF
keywords: MSP58; Nucleolus; RINT-1; Ribosomal genes