Alternative titles; symbols
HGNC Approved Gene Symbol: NCL
Cytogenetic location: 2q37.1 Genomic coordinates (GRCh38) : 2:231,453,531-231,464,484 (from NCBI)
Nucleolin, also known as C23, is an abundantly expressed acidic phosphoprotein of exponentially growing cells and is located mainly in dense fibrillar regions of the nucleolus. It is involved in the control of transcription of ribosomal RNA (rRNA) genes by RNA polymerase I, in ribosome maturation and assembly, and in nucleocytoplasmic transportation of ribosomal components (Srivastava et al., 1989).
Using a bovine cDNA probe in a lambda-gt10 human retina library, Srivastava et al. (1989) isolated a cDNA containing the entire coding region of nucleolin. The cDNA hybridized to a transcript of 3,000 bases from fast-dividing cells, as well as terminally differentiated tissues of several species. Translation of the nucleotide sequence showed a long open reading frame encoding a predicted 707-amino acid protein with several distinct domains.
Using in vitro pull-down assays, Ying et al. (2000) showed that A-Myb (MYBL1; 159405) and c-Myb (MYB; 189990), but not B-Myb (MYBL2; 601415), interacted with nucleolin. Coimmunoprecipitation assays confirmed the interaction in a human lymphoma cell line. Cotransfection of nucleolin with c-Myb and a reporter plasmid revealed that nucleolin inhibited the transcriptional activity of c-Myb in a dose-dependent manner. Mutational analysis indicated that the R2 and R3 repeats of c-Myb were sufficient for nucleolin binding and that arg161, which is found only in c-Myb and A-Myb but not in B-Myb, was critical for this interaction.
Using affinity chromatography with immobilized L-selectin (SELL; 153240), mass spectroscopy, and cell-surface labeling, Harms et al. (2001) showed that nucleolin is partly exposed on the cell surface and is a ligand of L-selectin in human leukocytes and hematopoietic progenitor cells.
Using Northern blot and EMSA analyses, Grinstein et al. (2002) found that nucleolin bound during S-phase in a sequence-specific manner to the enhancer of HPV18, a human papillomavirus strain highly associated with the development of cervical cancer. Treatment with nucleolin antisense inhibited HPV18 oncogene transcription and blocked proliferation of HPV18-positive cervical cancer cells. In contrast, nucleolin had no effect on HPV16 oncogene transcription or proliferation of HPV16-positive cervical cancer cells. Immunohistochemical analysis showed that nucleolin expression shifted from a diffuse, homogeneous nuclear pattern to a speckled nuclear distribution in HPV18-positive precancerous and cancerous cervical uterine tissue. Grinstein et al. (2002) concluded that nucleolin is directly linked to HPV18-induced cervical carcinogenesis.
Early apoptotic human Jurkat T cells undergo capping of CD43 (SPN; 182160), and its polylactosaminyl saccharide chains serve as ligands for phagocytosis by macrophages. Hirano et al. (2005) showed that nucleolin is the polylactosaminoglycan-binding receptor on macrophages. Nucleolin-transfected HEK293 cells expressed nucleolin on the cell surface and bound early apoptotic cells but not phosphatidylserine-exposing late apoptotic cells. The binding of early apoptotic cells was inhibited by anti-nucleolin antibody, by polylactosamine-containing oligosaccharides, and by anti-CD43 antibody. Hirano et al. (2005) concluded that nucleolin is a macrophage receptor for apoptotic cells.
Using a yeast 2-hybrid screen and in vitro and in vivo binding assays, including reciprocal immunoprecipitation assays, Tompkins et al. (2006) showed that nucleolin bound the p19(ARF) isoform of CDKN2A (600160), but not the p16(INK4A) isoform.
Using protein pull-down assays to identify proteins in 293T cells that associated with acetylated interferon regulatory factor-2 (IRF2; 147576), Masumi et al. (2006) identified nucleolin. Nucleolin in the presence of the transcription regulatory factor PCAF (602303) enhanced IRF2-dependent H4 (see 602822) promoter activity in NIH3T3 mouse fibroblasts. Nucleolin knockdown using small interfering RNA (siRNA) reduced IRF2/PCAF-mediated promoter activity. Chromatin immunoprecipitation analysis indicated that PCAF transfection increased the interaction of nucleolin with IRF2 bound to the H4 promoter. Masumi et al. (2006) concluded that nucleolin is recruited to acetylated IRF2, thereby contributing to gene regulation crucial for cell growth control.
By immunoprecipitation analysis using membrane fractions of human mammary epithelial cells, Shi et al. (2007) showed that endostatin (120328), an inhibitor of angiogenesis and tumor growth, specifically bound to cell surface nucleolin with high affinity. Blockage of nucleolin with neutralizing antibody or knockdown of nucleolin by RNA interference countered the antiendothelial activity of endostatin and abrogated its antiangiogenic and antitumor activity in vivo. Nucleolin and endostatin colocalized on the cell surface of endothelial cells in tumors, and endostatin was internalized and transported into cell nuclei of endothelial cells via nucleolin. In the nucleus, phosphorylation of nucleolin, which is critical for cell proliferation, was inhibited by endostatin. Shi et al. (2007) concluded that nucleolin is an endostatin receptor that mediates the antiangiogenic and antitumor activities of endostatin.
Padilla et al. (2008) found that BIG1 (ARFGEF1; 604141) coprecipitated with nucleolin from nuclei of human hepatoma cells. Incubation of nuclei with RNase A or DNase abolished the interaction, indicating that it depended on nucleic acids, and Padilla et al. (2008) showed that U3 snoRNA (see 180710) was associated with BIG1 and nucleolin in nuclei. The complex also contained fibrillarin (FBL; 134795), nucleoporin p62 (NUP62; 605815), and La (SSB; 109090). Fibrillarin was not present in complexes containing BIG1 and nucleolin at the nuclear envelope, suggesting that BIG1 and nucleolin participate in dynamic molecular complexes that change composition while moving through nuclei.
Using antibody neutralization, competition, and RNA interference (RNAi) assays, as well as expression of human nucleolin in nonpermissive insect cells, Tayyari et al. (2011) demonstrated that respiratory syncytial virus (RSV) interacted with host cell nucleolin via the viral fusion envelope glycoprotein and bound specifically to nucleolin at the apical cell surface. RNAi-mediated knockdown of lung nucleolin significantly reduced RSV infection in mice. Tayyari et al. (2011) concluded that nucleolin is a functional RSV receptor in vitro and in vivo.
Tominaga et al. (2011) found that microRNA-494 (MIR494; 616036) and HuR (ELAVL1; 603466) competed for binding to the 3-prime UTR of the NCL transcript in HeLa cells. MIR494 inhibited NCL translation by targeting NCL to RNA processing bodies. Conversely, HuR promoted NCL translation by targeting the transcript to polysomes. Neither regulator altered NCL mRNA content.
Srivastava et al. (1990) found that the NCL gene has 14 exons and spans approximately 11 kb. Sequences in the 5-prime flanking region and the first intron contain a high content of GC residues consistent with nucleolin being a housekeeping gene. Introns 3 and 6 contain complete Alu repeats in reverse orientation relative to the gene, and these are followed by 9-nucleotide poly(A) tracts. Intron 6 contains a partial Alu repeat and a partial KpnI repeat. Southern blot analysis indicated that the gene is present in 1 copy in the haploid genome.
Nicoloso et al. (1994) demonstrated that intron 11 of the NCL gene in humans and rodents encodes a small nucleolar RNA (snoRNA), which they designated U20 (604012). Sequence analysis revealed that U20 contains a region of perfect complementarity with a conserved sequence in 18S rRNA, suggesting that like nucleolin, it may be involved in the formation of the small ribosomal subunit.
Rebane and Metspalu (1999) identified the snoRNA U82 (SNORD82; 611133) in intron 5 of the human, rat, and mouse nucleolin genes. They stated that intron 12 contains the snoRNA U23 (SNORA75).
By analysis of rodent/human somatic cell hybrids, Srivastava et al. (1989) mapped the NCL gene to 2q12-qter.
Grinstein, E., Wernet, P., Snijders, P. J. F., Rosl, F., Weinert, I., Jia, W., Kraft, R., Schewe, C., Schwabe, M., Hauptmann, S., Dietel, M., Meijer, C. J. L. M., Royer, H.-D. Nucleolin as activator of human papillomavirus type 18 oncogene transcription in cervical cancer. J. Exp. Med. 196: 1067-1078, 2002. [PubMed: 12391018] [Full Text: https://doi.org/10.1084/jem.20011053]
Harms, G., Kraft, R., Grelle, G., Volz, B., Dernedde, J., Tauber, R. Identification of nucleolin as a new L-selectin ligand. Biochem. J. 360: 531-538, 2001. [PubMed: 11736641] [Full Text: https://doi.org/10.1042/0264-6021:3600531]
Hirano, K., Miki, Y., Hirai, Y., Sato, R., Itoh, T., Hayashi, A., Yamanaka, M., Eda, S., Beppu, M. A multifunctional shuttling protein nucleolin is a macrophage receptor for apoptotic cells. J. Biol. Chem. 280: 39284-39293, 2005. [PubMed: 16135517] [Full Text: https://doi.org/10.1074/jbc.M505275200]
Masumi, A., Fukazawa, H., Shimazu, T., Yoshida, M., Ozato, K., Komuro, K., Yamaguchi, K. Nucleolin is involved in interferon regulatory factor-2-dependent transcriptional activation. Oncogene 25: 5113-5124, 2006. [PubMed: 16582966] [Full Text: https://doi.org/10.1038/sj.onc.1209522]
Nicoloso, M., Caizergues-Ferrer, M., Michot, B., Azum, M.-C., Bachellerie, J.-P. U20, a novel small nucleolar RNA, is encoded in an intron of the nucleolin gene in mammals. Molec. Cell. Biol. 14: 5766-5776, 1994. [PubMed: 8065311] [Full Text: https://doi.org/10.1128/mcb.14.9.5766-5776.1994]
Padilla, P. I., Uhart, M., Pacheco-Rodriguez, G., Peculis, B. A., Moss, J., Vaughan, M. Association of guanine nucleotide-exchange protein BIG1 in HepG2 cell nuclei with nucleolin, U3 snoRNA, and fibrillarin. Proc. Nat. Acad. Sci. 105: 3357-3361, 2008. [PubMed: 18292223] [Full Text: https://doi.org/10.1073/pnas.0712387105]
Rebane, A., Metspalu, A. U82, a novel snoRNA identified from the fifth intron of human and mouse nucleolin gene. Biochim. Biophys. Acta 1446: 426-430, 1999. [PubMed: 10524220] [Full Text: https://doi.org/10.1016/s0167-4781(99)00093-7]
Shi, H., Huang, Y., Zhou, H., Song, X., Yuan, S., Fu, Y., Luo, Y. Nucleolin is a receptor that mediates antiangiogenic and antitumor activity of endostatin. Blood 110: 2899-2906, 2007. [PubMed: 17615292] [Full Text: https://doi.org/10.1182/blood-2007-01-064428]
Srivastava, M., Fleming, P. J., Pollard, H. B., Burns, A. L. Cloning and sequencing of the human nucleolin cDNA. FEBS Lett. 250: 99-105, 1989. [PubMed: 2737305] [Full Text: https://doi.org/10.1016/0014-5793(89)80692-1]
Srivastava, M., McBride, O. W., Fleming, P. J., Pollard, H. B., Burns, A. L. Genomic organization and chromosomal localization of the human nucleolin gene. J. Biol. Chem. 265: 14922-14931, 1990. [PubMed: 2394707]
Tayyari, F., Marchant, D., Moraes, T. J., Duan, W., Mastrangelo, P., Hegele, R. G. Identification of nucleolin as a cellular receptor for human respiratory syncytial virus. Nature Med. 17: 1132-1135, 2011. [PubMed: 21841784] [Full Text: https://doi.org/10.1038/nm.2444]
Tominaga, K., Srikantan, S., Lee, E. K., Subaran, S. S., Martindale, J. L., Abdelmohsen, K., Gorospe, M. Competitive regulation of nucleolin expression by HuR and miR-494. Molec. Cell. Biol. 31: 4219-4231, 2011. [PubMed: 21859890] [Full Text: https://doi.org/10.1128/MCB.05955-11]
Tompkins, V., Hagen, J., Zediak, V. P., Quelle, D. E. Identification of novel ARF binding proteins by two-hybrid screening. Cell Cycle 5: 641-646, 2006. [PubMed: 16582619]
Ying, G.-G., Proost, P., van Damme, J., Bruschi, M., Introna, M., Golay, J. Nucleolin, a novel partner for the Myb transcription factor family that regulates their activity. J. Biol. Chem. 275: 4152-4158, 2000. [PubMed: 10660576] [Full Text: https://doi.org/10.1074/jbc.275.6.4152]