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PLOS ONE  2008 

The Proto-Oncogene Int6 Is Essential for Neddylation of Cul1 and Cul3 in Drosophila

DOI: 10.1371/journal.pone.0002239

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Int6 is a proto-oncogene implicated in various types of cancer, but the mechanisms underlying its activity are not clear. Int6 encodes a subunit of the eukaryotic translation initiation factor 3, and interacts with two related complexes, the proteasome, whose activity is regulated by Int6 in S. pombe, and the COP9 signalosome. The COP9 signalosome regulates the activity of Cullin-Ring Ubiquitin Ligases via deneddylation of their cullin subunit. We report here the generation and analysis of two Drosophila mutants in Int6. The mutants are lethal demonstrating that Int6 is an essential gene. The mutant larvae accumulate high levels of non-neddylated Cul1, suggesting that Int6 is a positive regulator of cullin neddylation. Overexpression in Int6 in cell culture leads to accumulation of neddylated cullins, further supporting a positive role for Int6 in regulating neddylation. Thus Int6 and the COP9 signalosome play opposing roles in regulation of cullin neddylation.


[1]  Marchetti A, Buttitta F, Miyazaki S, Gallahan D, Smith GH, et al. (1995) Int-6, a highly conserved, widely expressed gene, is mutated by mouse mammary tumor virus in mammary preneoplasia. J Virol 69: 1932–1938.
[2]  Rasmussen SB, Kordon E, Callahan R, Smith GH (2001) Evidence for the transforming activity of a truncated Int6 gene, in vitro. Oncogene 20: 5291–5301.
[3]  Mayeur GL, Hershey JW (2002) Malignant transformation by the eukaryotic translation initiation factor 3 subunit p48 (eIF3e). FEBS Lett 514: 49–54.
[4]  Morris C, Jalinot P (2005) Silencing of human Int-6 impairs mitosis progression and inhibits cyclin B-Cdk1 activation. Oncogene 24: 1203–1211.
[5]  Hoareau Alves K, Bochard V, Rety S, Jalinot P (2002) Association of the mammalian proto-oncoprotein Int-6 with the three protein complexes eIF3, COP9 signalosome and 26S proteasome. FEBS Lett 257: 15–21.
[6]  Asano K, Merrick WC, Hershey JW (1997) The translation initiation factor eIF3-p48 subunit is encoded by int-6, a site of frequent integration by the mouse mammary tumor virus genome. J Biol Chem 272: 23477–23480.
[7]  Yen HC, Gordon C, Chang EC (2003) Schizosaccharomyces pombe Int6 and Ras homologs regulate cell division and mitotic fidelity via the proteasome. Cell 112: 207–217.
[8]  Yahalom A, Kim TH, von Arnim AG, Chamovitz DA (2007) Arabidopsis eIF3e is regulated by the COP9 signalosome and impacts development and protein translation. Plant J. In press.
[9]  Schwechheimer C, Serino G, Callis J, Crosby WL, Lyapina S, et al. (2001) Interactions of the COP9 signalosome with the E3 ubiquitin ligase SCFTIR1 in mediating auxin response. Science 292: 1379–1382.
[10]  Cope GA, Suh GS, Aravind L, Schwarz SE, Zipursky SL, et al. (2002) Role of predicted metalloprotease motif of Jab1/Csn5 in cleavage of Nedd8 from Cul1. Science 298: 608–611.
[11]  He Q, Cheng P, He Q, Liu Y (2005) The COP9 signalosome regulates the Neurospora circadian clock by controlling the stability of the SCFFWD-1 complex. Genes Dev 19: 1518–1531.
[12]  Wu JT, Lin HC, Hu YC, Chien CT (2005) Neddylation and deneddylation regulate Cul1 and Cul3 protein accumulation. Nat Cell Biol 7: 1014–1020.
[13]  Gusmaroli G, Figueroa P, Serino G, Deng XW (2007) Role of the MPN subunits in COP9 signalosome assembly and activity, and their regulatory interaction with Arabidopsis Cullin3-based E3 ligases. Plant Cell 19: 564–581.
[14]  Wee S, Geyer RK, Toda T, Wolf DA (2005) CSN facilitates Cullin-RING ubiquitin ligase function by counteracting autocatalytic adapter instability. Nat Cell Biol 7: 387–391.
[15]  Karniol B, Malec P, Chamovitz DA (1999) Arabidopsis FUSCA5 encodes a novel phosphoprotein that is a component of the COP9 complex. Plant Cell 11: 839–848.
[16]  Yahalom A, Kim TH, Winter E, Karniol B, von Arnim AG, et al. (2001) Arabidopsis eIF3e (INT-6) associates with both eIF3c and the COP9 signalosome subunit CSN7. J Biol Chem 276: 334–340.
[17]  Ou CY, Lin YF, Chen YJ, Chien CT (2002) Distinct protein degradation mechanisms mediated by Cul1 and Cul3 controlling Ci stability in Drosophila eye development. Genes Dev 16: 2403–2414.
[18]  Oron E, Mannervik M, Rencus S, Harari-Steinberg O, Neuman-Silberberg S, et al. (2002) COP9 signalosome subunits 4 and 5 regulate multiple pleiotropic pathways in Drosophila melanogaster. Development 129: 4399–4409.
[19]  Mistry H, Wilson BA, Roberts I, O'Kane CJ, Skeath JB (2004) Cullin-3 regulates pattern formation, external sensory organ development and cell survival during Drosophila development. Mech Dev 121: 1495–1507.
[20]  Szlanka T, Haracska L, Kiss I, Deák P, Kurucz E, et al. (2003) Deletion of proteasomal subunit S5a/Rpn10/p54 causes lethality, multiple mitotic defects and overexpression of proteasomal genes in Drosophila melanogaster. J Cell Sci 116: 1023–1033.
[21]  Grumbling G, Strelets V, The FlyBase Consortium (2006) FlyBase: anatomical data, images and queries. Nucleic Acids Research 34: D484–D488. doi:10.1093/nar/gkj068.
[22]  Reichhart JM, Ferrandon D (1998) Green balancers. D I S 81: 201–202.
[23]  Oron E, Tuller T, Li L, Rozovsky N, Yekutieli D, et al. (2007) Genomic analysis of COP9 signalosome function in Drosophila melanogaster reveals a role in temporal regulation of gene expression. Mol Syst Biol 3: 108.
[24]  Whitfield WG, Gonzalez C, Maldonado-Codina G, Glover DM (1990) The A- and B-type cyclins of Drosophila are accumulated and destroyed in temporally distinct events that define separable phases of the G2-M transition. EMBO J 9: 2563–2572.
[25]  Freilich S, Oron E, Kapp Y, Nevo-Caspi Y, Orgad S, et al. (1999) The COP9 signalosome is essential for development of Drosophila melanogaster. Curr Biol 9: 1187–1190.
[26]  Chou TB, Perrimon N (1996) The autosomal FLP-DFS technique for generating germline mosaics in Drosophila melanogaster. Genetics 144: 1673–1679.
[27]  Doronkin S, Djagaeva I, Beckendorf SK (2003) The COP9 signalosome promotes degradation of cyclin E during early Drosophila oogenesis. Dev Cell 4: 699–710.
[28]  Morimoto M, Nishida T, Nagayama Y, Yasuda H (2003) Nedd8-modification of Cul1 is promoted by Roc1 as a Nedd8-E3 ligase and regulates its stability. Biochem Biophys Res Comm 301: 392–398.
[29]  Mack DL, Boulanger CA, Callahan R, Smith GH (2007) Expression of truncated Int6/eIF3e in mammary alveolar epithelium leads to persistent hyperplasia and tumorigenesis. Breast Cancer Res 9: R42.
[30]  Miyazaki S, Rasmussen S, Imatani A, Diella F, Sullivan DT, et al. (1999) Characterization of the Drosophila ortholog of mouse eIF-3p48/INT6. Gene 233: 241–247.
[31]  Bandyopadhyay A, Matsumoto T, Maitra U (2000) Fission yeast Int6 is not essential for global translation initiation, but deletion of int6(+) causes hypersensitivity to caffeine and affects spore formation. Mol Biol Cell 11: 4005–4018.
[32]  Akiyoshi Y, Clayton J, Phan L, Yamamoto M, Hinnebusch AG, et al. (2001) Fission yeast homolog of murine Int-6 protein, encoded by mouse mammary tumor virus integration site, is associated with the conserved core subunits of eukaryotic translation initiation factor 3. J Biol Chem 276: 10056–10062.
[33]  Masutani M, Sonenberg N, Yokoyama S, Imataka H (2007) Reconstitution reveals the functional core of mammalian eIF3. EMBO J 26: 3373–3383.


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