Journal of Cell Science, Vol 108, Issue 5 1911-1920, Copyright © 1995 by Company of Biologists

JOURNAL ARTICLES

Cell-cycle-dependent alterations of a highly phosphorylated nucleolar protein p130 are associated with nucleologenesis

CY Pai, HK Chen, HL Sheu and NH Yeh
Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China.

We identified a novel human nucleolar phosphoprotein p130 (130 kDa) using a strategy for selecting monoclonal antibodies against nuclear proteins which oscillate in the cell cycle. p130 is localized in interphase nucleoli in a dotted manner. Complete extraction of p130 required a high concentration of salt (0.5 M NaCl) indicating that it binds firmly to the nucleolar components via ionic interaction. p130 is heavily phosphorylated, since alkaline phosphatase treatment converted the purified p130 into a 95 kDa product; this was further supported by the in vitro demonstration that cellular phosphatase and casein kinase II activities were responsible for the interchange of these two forms. Extracts of mitotic cells had lower concentrations of p130 compared to those of interphase cells suggesting that a proportion of p130 might be degraded during mitosis. Moreover, all the remaining p130 in mitotic cells was further phosphorylated, likely by a cdc2 kinase, resulting in increase in its solubility, and its dispersion throughout the entire cytoplasm. Thus, p130 in metaphase and anaphase cells was unable to be detected by immunofluorescence microscopy. At telophase, p130 reappeared and aggregated into a granular structure, resembling the prenucleolar bodies. These granules migrated from the nucleoplasm to the nucleoli in early G1-phase. Actinomycin D was able to induce segregation of p130-containing granules into the nucleoplasm, similar to the well-known behavior of the fibrillarin-containing granules, indicating that p130 is localized in the dense fibrillar component, a subnucleolar region for pre-rRNA synthesis and processing. The cDNA sequence of p130 revealed a remarkable feature, that a serine-rich stretch interspersed with acidic residues is repeated ten times. Such a characteristic is shared with a rat nucleolar phosphoprotein Nopp140, which is thought to shuttle between the nucleolus and the cytoplasm. Although p130 shows 74% identity to Nopp140, our observations suggest that during mitosis the functions of p130 are related to nucleologenesis.

This article has been cited by other articles:

				N. Kittur, G. Zapantis, M. Aubuchon, N. Santoro, D. P. Bazett-Jones, and U. T. Meier The Nucleolar Channel System of Human Endometrium Is Related to Endoplasmic Reticulum and R-Rings Mol. Biol. Cell, June 1, 2007; 18(6): 2296 - 2304. [Abstract] [Full Text] [PDF]

				K. Shimono, Y. Shimono, K. Shimokata, N. Ishiguro, and M. Takahashi Microspherule Protein 1, Mi-2{beta}, and RET Finger Protein Associate in the Nucleolus and Up-regulate Ribosomal Gene Transcription J. Biol. Chem., November 25, 2005; 280(47): 39436 - 39447. [Abstract] [Full Text] [PDF]

				J. Sagara, T. Higuchi, Y. Hattori, M. Moriya, H. Sarvotham, H. Shima, H. Shirato, K. Kikuchi, and S. Taniguchi Scapinin, a Putative Protein Phosphatase-1 Regulatory Subunit Associated with the Nuclear Nonchromatin Structure J. Biol. Chem., November 14, 2003; 278(46): 45611 - 45619. [Abstract] [Full Text] [PDF]

				F. MEGGIO and L. A. PINNA One-thousand-and-one substrates of protein kinase CK2? FASEB J, March 1, 2003; 17(3): 349 - 368. [Abstract] [Full Text] [PDF]

				S.-H. Wang, W.-J. Syu, K.-J. Huang, H.-Y. Lei, C.-W. Yao, C.-C. King, and S.-T. Hu Intracellular localization and determination of a nuclear localization signal of the core protein of dengue virus J. Gen. Virol., December 1, 2002; 83(12): 3093 - 3102. [Abstract] [Full Text] [PDF]

				C.-M. Chiu, Y.-G. Tsay, C.-J. Chang, and S.-C. Lee Nopp140 Is a Mediator of the Protein Kinase A Signaling Pathway That Activates the Acute Phase Response alpha 1-Acid Glycoprotein Gene J. Biol. Chem., October 11, 2002; 277(42): 39102 - 39111. [Abstract] [Full Text] [PDF]

				M. Schuhmacher, F. Kohlhuber, M. Holzel, C. Kaiser, H. Burtscher, M. Jarsch, G. W. Bornkamm, G. Laux, A. Polack, U. H. Weidle, et al. The transcriptional program of a human B cell line in response to Myc Nucleic Acids Res., January 15, 2001; 29(2): 397 - 406. [Abstract] [Full Text] [PDF]

				H.-K. Chen, C.-Y. Pai, J.-Y. Huang, and N.-H. Yeh Human Nopp140, Which Interacts with RNA Polymerase I: Implications for rRNA Gene Transcription and Nucleolar Structural Organization Mol. Cell. Biol., December 1, 1999; 19(12): 8536 - 8546. [Abstract] [Full Text] [PDF]

				C. A. Wise, L. C. Chiang, W. A. Paznekas, M. Sharma, M. M. Musy, J. A. Ashley, M. Lovett, and E. W. Jabs TCOF1 gene encodes a putative nucleolar phosphoprotein that exhibits mutations in Treacher Collins Syndrome throughout its coding region PNAS, April 1, 1997; 94(7): 3110 - 3115. [Abstract] [Full Text] [PDF]

				J Dixon, S J Edwards, I Anderson, A Brass, P J Scambler, and M J Dixon Identification of the complete coding sequence and genomic organization of the Treacher Collins syndrome gene. Genome Res., March 1, 1997; 7(3): 223 - 234. [Abstract] [PDF]

				U. T. Meier and U. T. Meier Comparison of the Rat Nucleolar Protein Nopp140 with Its Yeast Homolog SRP40. DIFFERENTIAL PHOSPHORYLATION IN VERTEBRATES AND YEAST J. Biol. Chem., August 9, 1996; 271(32): 19376 - 19384. [Abstract] [Full Text] [PDF]

				H. Hsu and N. Yeh Dynamic changes of NuMA during the cell cycle and possible appearance of a truncated form of NuMA during apoptosis J. Cell Sci., January 2, 1996; 109(2): 277 - 288. [Abstract] [PDF]

				C Cairns and B McStay Identification and cDNA cloning of a Xenopus nucleolar phosphoprotein, xNopp180, that is the homolog of the rat nucleolar protein Nopp140 J. Cell Sci., January 10, 1995; 108(10): 3339 - 3347. [Abstract] [PDF]

				J. M. Waggener and P. J. DiMario Two Splice Variants of Nopp140 in Drosophila melanogaster Mol. Biol. Cell, January 1, 2002; 13(1): 362 - 381. [Abstract] [Full Text] [PDF]