Functional Regions of Ornithine Decarboxylase Antizyme

Ichiba, Tamotsu; Matsufuji, Senya; Miyazaki, Youichi; Murakami, Yasuko; Tanaka, K.; Ichihara, Akira; Hayashi, Shin Ichi

doi:10.1006/bbrc.1994.1651

Cited by 42 publications

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“…4B). In contrast, mutants with further deletions from the C terminus, such as EGFP-AZ1 1-45 , EGFP-AZ1 1-40 , EGFP-AZ1 , and EGFP-AZ1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] , were distributed in the cytoplasm and the nucleus irrespective of LMB treatment (Fig. 4B).…”

Section: Az1 Contains Two Nuclear Exportmentioning

confidence: 99%

“…When cellular polyamine levels are high, ϩ1 frameshifting occurs after the 68th codon is decoded, resulting in the full-length antizyme protein (amino acid residues 1-227). All of the known regulatory activities of AZ1 are present in amino acid residues 69 -227 (12). A second AUG exists in AZ1 mRNA at the 34th codon, and this second AUG is also utilized as initiation codon (11,13).…”

mentioning

confidence: 99%

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Identification of Nuclear Export Signals in Antizyme-1

Murai

Murakami

Matsufuji

2003

Journal of Biological Chemistry

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Antizyme-1 (AZ1) is a protein that negatively regulates polyamine synthesis by inhibiting the key synthetic enzyme ornithine decarboxylase and targeting it for degradation by the 26 S proteasome. Recent work shows that antizyme protein translocates to the nucleus during mouse development (Gritli-Linde, A., Nilssom, J., Bohlooly, Y. M., Heby, O., and Linde, A. (2001) Dev. Dyn. 220, 259 -275). However, the significance and mechanism of this phenomenon remain unclear. In this study, we expressed AZ1 fused with enhanced green fluorescent protein (EGFP) to study its localization in a living cell. We found that EGFP-AZ1 was predominantly localized in the cytoplasm and that treatment with leptomycin B, a specific inhibitor of chromosomal region maintenance 1 (CRM1) induced nuclear accumulation of EGFP-AZ1 in Chinese hamster ovary and NIH3T3 cells. Two independent nuclear export signal (NES) sequences, each containing essential hydrophobic residues, were identified in the 50 N-terminal amino acid residues and in the central part of AZ1. The activity of the second NES was inhibited by an N-terminal adjacent region and was only revealed in N-terminal truncated constructs. Both NESs were active when fused to an artificial nuclear protein SV40-NLS-EGFP-EGFP. The ability of AZ1 to shuttle between the nucleus and the cytoplasm suggests that it has a novel function in the nucleus.Polyamines are ubiquitous organic cations with tightly regulated cellular concentrations and are essential for cell growth and development (1, 2). Antizyme (AZ) 1 was first described as an inhibitor of ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis (3). When cellular polyamine levels rise, AZ is induced and then binds to the monomeric form of ODC (4, 5), which makes the enzyme a preferential substrate for proteolysis by the 26 S proteasome without ubiquitination (6). AZ also inhibits the uptake of extracellular polyamines (7,8). There are at least three independent antizyme isoforms conserved among mammals. AZ1 and AZ2 have a wide tissue distribution, whereas AZ3 is testis-specific (9, 10). Expression of AZs is induced by a unique translational frameshift mechanism (11). For AZ1, when cellular polyamine levels are low, the polypeptide corresponding to amino acid residues 1-68 is produced and translation is terminated at the following UGA codon (11). When cellular polyamine levels are high, ϩ1 frameshifting occurs after the 68th codon is decoded, resulting in the full-length antizyme protein (amino acid residues 1-227). All of the known regulatory activities of AZ1 are present in amino acid residues 69 -227 (12). A second AUG exists in AZ1 mRNA at the 34th codon, and this second AUG is also utilized as initiation codon (11, 13). The two resulting translation products have different half-lives (14). Furthermore, it has been suggested that the N-terminal region of the translation product from the first AUG contains a putative mitochondrial targeting signal and thus the distribution of AZ1 may depend on this region (15). It is curre...

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Section: Az1 Contains Two Nuclear Exportmentioning

confidence: 99%

mentioning

confidence: 99%

Identification of Nuclear Export Signals in Antizyme-1

Murai

Murakami

Matsufuji

2003

Journal of Biological Chemistry

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“…Amino acid residues in OAZ-t that are conserved in more than two OAZs are shown in a grey background. The somatic OAZ1 regions to bind to ODC (ODC binding sites I and II) and to promote degradation of ODC (ODC degradation promoting site) are boxed, respectively (Tewari et al 1994). degradation promoting site (amino acid residues 69±72) and ODC binding site II (amino acid residues 178±186) were highly conserved in OAZ-t though ODC binding site I was not (Ichiba et al 1994).…”

Section: Molecular Cloning Of the Oaz-t Genementioning

confidence: 99%

Identification and characterization of testis specific ornithine decarboxylase antizyme (OAZ‐t) gene: expression in haploid germ cells and polyamine‐induced frameshifting

Tosaka¹,

Tanaka²,

Yano

et al. 2000

Genes to Cells

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Section: Identi®cation Of the Domain Of Antizyme Responsible For The mentioning

confidence: 99%

“…a, a', and a''; Regions indispensable for the acceleration of decay encompassing 103 ± 136 (Mamroud-Kidron et al, 1994), 70 ± 120 (Li et al, 1994 or 88 ± 118 (Ichiba et al, 1994), respectively. b, b' and b''; Regions postulated to bind ODC and inhibit its enzymatic activity encompassing 121 ± 227 (b) (Li et al, 1994) or 122 ± 144 (b') and 211 ± 218 (b'') (Ichiba et al, 1994) of rat antizyme. FSAZ-wt (aa 64 ± 227) and the other deletion mutant clones were generated by the addition of a start codon with +1 frameshift, so that FSAZ-wt (aa 64 ± 227), FSAZmt (aa 135 ± 227), FSAZ-mt (aa 135 ± 167) and FSAZ-mt (aa 169 ± 227) clones encode 64 ± 227, 135 ± 227, 135 ± 167 and 169 ± 227 of the amino acid sequence of mouse antizyme.…”

Section: Identi®cation Of the Domain Of Antizyme Responsible For The mentioning

confidence: 99%

Anti-tumor activity of antizyme which targets the ornithine decarboxylase (ODC) required for cell growth and transformation

et al. 1999

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Cell proliferation and transformation induced by growth factor stimulation or by carcinogens, viruses, or oncogenes are characterized by an associated increase in polyamine levels, which is mediated by increased polyamine biosynthesis and enhanced uptake of polyamines. Polyamine biosynthesis is catalyzed particularly, in the level of ornithine decarboxylase (ODC). The elevation of cellular polyamine levels on the other hand accelerates the induction of ornithine decarboxylase antizyme (antizyme), which is involved not only in ODC-degradation, but in the negative regulation of polyamine transport. Taking advantage of these characteristics of antizyme, the potential of antizyme as a factor having anti-cell growth and anti-tumor activity was investigated. We show that antizyme can induce cell death associated with a rapid decline of intracellular polyamine contents. The possible anti-tumor activities of ectopically expressed antizyme were tested in p21H-ras (Val 12)-transformed NIH3T3 cells and several human malignant cell lines including a line with loss of p53 expression, and they were shown to be as sensitive as nontransformed NIH3T3 cells in vitro. The in vivo antitumor activity was also tested using nude mice inoculated with H-ras transformed NIH3T3 cells that had been transfected with inducible antizyme expression vector and the results showed that antizyme expression in vivo blocks tumor formation in these mice. These results suggest that ectopic antizyme expression is of possible therapeutic bene®t in the treatment of cancer, which is mediated by ODC inactivation and intracellular polyamine depletion.

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Functional Regions of Ornithine Decarboxylase Antizyme

Cited by 42 publications

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Identification of Nuclear Export Signals in Antizyme-1

Identification of Nuclear Export Signals in Antizyme-1

Identification and characterization of testis specific ornithine decarboxylase antizyme (OAZ‐t) gene: expression in haploid germ cells and polyamine‐induced frameshifting

Anti-tumor activity of antizyme which targets the ornithine decarboxylase (ODC) required for cell growth and transformation

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