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At least 19 recordsLinked to original sources

PubMed1989

Characterization of the cDNA encoding human nucleophosmin and studies of its role in normal and abnormal growth.

A cDNA encoding human nucleophosmin (protein B23) was obtained by screening a human placental cDNA library in lambda gtll first with monoclonal antibody to rat nucleophosmin and then with confirmed partial cDNA of human nucleophosmin as probes. The cDNA had 1311 bp with a coding sequence encoding a protein of 294 amino acids. The identity of the cDNA was confirmed by the presence of encoded amino acid sequences identical with those determined by sequencing pure rat nucleophosmin (a total of 138 amino acids). The most striking feature of the sequence is an acidic cluster located in the middle of the molecule. The cluster consists of 26 Asp/Glu and 1 Phe and Ala. Comparison of human nucleophosmin and Xenopus nucleolar protein NO38 shows 64.3% sequence identity. The N-terminal 130 amino acids of human nucleophosmin also bear 50% identity with that of Xenopus nucleoplasmin. Northern blot analysis of rat liver total RNA with a partial nucleophosmin cDNA as probe demonstrated a homogeneous mRNA band of about 1.6 kb. Similar observations were made in hypertrophic rat liver and Novikoff hepatoma. However, the quantity of nucleophosmin mRNA is 50- and 5-fold higher in Novikoff hepatoma and hypertrophic rat liver, respectively, when compared with normal rat liver. Dot blot analysis also showed a nucleophosmin mRNA ratio of 64:5:1 in the three types of rat liver. When the protein levels were compared with Western blot immunoassays, Novikoff hepatoma showed 20 times more nucleophosmin, while only about 5 times more nucleophosmin was observed in hypertrophic rat liver than in unstimulated normal liver.

Amino Acid Sequence↗

PubMed1995

Cell cycle phase-dependent changes of localization and oligomerization states of nucleophosmin / B23.

Nucleophosmin / B23, an abundant nucleolar phosphoprotein, accumulates in the nucleoplasm of cells during the stationary phase of growth or after exposure to selected cytotoxic drugs [Chan, P.K. (1992) Exp. Cell Res. 203, 174-181]. Monomeric and hexameric forms of nucleophosmin / B23 are present in cells [Yung, B.Y.M. and Chan, P.K. (1987) Biochim. Biophys. Acta. 925, 74-82]. Using indirect immunofluorescence, here we show that there are changes in nucleophosmin / B23's cellular localizations throughout the cell cycle. The alternation of the nuclear and nucleolar localizations of nucleophosmin / B23 is most frequently observed in cells of G1 and G1/S phases. The incidence of the changes of localizations of nucleophosmin / B23 decreases as cells enter into S and G2 phases. In parallel, using Western blotting, the reversible change of oligomerization states between the hexameric and monomeric forms of nucleophosmin / B23 is also found to occur most frequently in cells of G1 and G1/S phases. As cells progressed into S, G2 and M phases, the frequency of the reversible change of hexameric and monomeric forms of nucleophosmin / B23 decreases. These findings suggest that nucleophosmin / B23 being possibly involved in rRNA processing and transport, is highly active at G1 and G1/S phases as demonstrated by the dynamic, reversible changes of localization and oligomerization states of nucleophosmin / B23.

Biological Transport, Active↗

PubMed1991

Dipyridamole enhancement of doxorubicin-induced translocation of nucleophosmin and inhibition of cell growth in HL-60 cells.

Dipyridamole (DPM) enhanced sensitivity to doxorubicin (DOX) in a human leukemia cell line that was already relatively sensitive to this agent. Using an immunofluorescence technique, we determined the localization of nucleophosmin (protein B23) in HL-60 cells after incubation with DOX in the absence and presence of DPM. Bright nucleolar fluorescence was observed in control HL-60 cells. The addition of DOX (0.1-0.25 micrograms/ml) in the culture system resulted in time- and dose-dependent induction of nucleophosmin translocation from the nucleolus to nucleoplasm and inhibition of cell growth. DPM (5 microM) alone had no effect on nucleophosmin translocation and inhibition of cell growth. However, the addition of DPM to the cells enhanced DOX-stimulated translocation of nucleophosmin. There was a good correlation between the DPM enhancement of DOX-induced nucleophosmin translocation and the increased inhibition of cell growth. The cell number decreased to a greater extent within a shorter time period under treatment with DOX in the presence of DPM. Short exposure (0.5 hr) of HL-60 cells to DOX induced dose-response nucleophosmin translocation and cell growth inhibition. Such effects of a short exposure to DOX were also enhanced by DPM (5 microM) included in the fresh medium after removal of DOX. This was in agreement with the observation that DPM could increase the cellular DOX by inhibiting the drug efflux from the cells. These results demonstrate that DPM, being able to increase and retain the intracellular levels of DOX, can markedly enhance the cytotoxicity of DOX, and suggest possible clinical application. "Nucleophosmin translocation", as observed by immunofluorescence, could be useful in determining the efficacy of combinations of DOX and DPM in cancer chemotherapy.

Cell Division↗

PubMed1995

Translocation of nucleophosmin from nucleoli to nucleoplasm requires ATP.

The movement of nucleophosmin from nucleoli to nucleoplasm in HeLa cells induced by cytotoxic drugs and detected by immunofluorescence is inhibited by concomitant treatment with antimycin A in glucose-free medium. Incubation of HeLa cells with antimycin A (300 nM; 30 min) and glucose-free medium resulted in an approximately 90% decrease in cellular ATP pools. To study the biochemical events involved in nucleophosmin translocation, we used an in vitro system consisting of Triton-permeabilized HeLA cells. Incubation of permeabilized cells with ATP (0.5 mM; 1 h) resulted in the translocation of nucleophosmin from nucleoli to nucleoplasm and cytoplasm. Similarly to drug-induced nucleophosmin translocation in whole cultured cells, there is no reduction (measured by e.l.i.s.a.) or degradation of nucleophosmin or change in the ratio of the high-molecular-mass form to the monomeric form (ascertained by Western blotting) during ATP treatment of permeabilized cells. Together, these results indicate a requirement for ATP for redistribution of nucleophosmin from nucleoli to nucleoplasm. Because this permeabilized cell model is simple and efficient and works effectively with exogenous factors, it should provide a powerful tool for investigating the biochemical features of nucleophosmin translocation from nucleoli to nucleoplasm.

Adenosine Triphosphate↗

PubMed2006

Nucleophosmin is a novel Bax chaperone that regulates apoptotic cell death.

The proapoptotic B-cell lymphoma-2 family protein Bax is a key regulatory point in the intrinsic apoptotic pathway. However, the factors controlling the process of Bax activation and translocation to mitochondria have yet to be fully identified and characterized. We performed affinity chromatography using peptides corresponding to the mitochondrial-targeting region of Bax, which is normally sequestered within the inactive structure. The molecular chaperone nucleophosmin was identified as a novel Bax-binding protein by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Reciprocal co-immunoprecipitation and proximity assays confirmed the Bax-nucleophosmin protein-protein interaction and verified that nucleophosmin only bound to activated conformationally altered Bax. Confocal microscopy in a cell-based apoptosis model, demonstrated that nucleophosmin translocation from nucleolus to cytosol preceded Bax movement. Specific knockdown of nucleophosmin expression using RNAi attenuated apoptosis as measured by mitochondrial cytochrome c release and activation of the caspase cascade. In a mouse model of ischaemic stroke, subcellular fractionation studies verified that nucleophosmin translocation occurred within 3 h, at a time before Bax translocation but after Bax conformational changes have occurred. Thus, we have elucidated a novel molecular mechanism whereby Bax becomes activated and translocates to the mitochondria to orchestrate mitochondrial dysfunction and apoptotic cell death, which opens new avenues for therapeutic intervention.

Animals↗

PubMed1992

Schedule-dependent sphinganine potentiation of retinoic acid-induced differentiation, cell growth inhibition, and nucleophosmin translocation in a human leukemia cell line (HL-60).

Induction of differentiation, inhibition of cell growth, and localization of nucleophosmin in HL-60 cells under the treatment of retinoic acid (RA) were studied. Bright nucleolar fluorescence was observed in control promyelocytic growing cells. The addition of RA in the culture system resulted in time- and dose-dependent induction of differentiation, cell growth inhibition, and nucleophosmin translocation from nucleoli to nucleoplasm. Unlike the control cells, many fewer nucleophosmin-associated preribosomal ribonucleoprotein particles (pre-rRNPs) could be obtained from nucleoli of RA-treated cells. Addition of sphinganine, an inhibitor of protein kinase C, facilitated the RA-induced differentiation, nucleophosmin translocation, and cell growth inhibition. Cells treated with sphinganine were more responsive to RA. Differentiation, translocation of nucleophosmin, and inhibition of cell growth occurred with lesser doses of RA or in shorter incubation times in the presence of sphinganine. Significant numbers of HL-60 cells could be rescued from the effects of RA upon the removal of RA after 2-h drug exposure. Pretreatment but not posttreatment of HL-60 cells with sphinganine, however, modulated the reversibility of the effects induced by short-exposure RA treatment. These results indicated that RA therapy can be improved by the pretreatment or the concurrent use of a modulator of protein kinase C activity. Nucleophosmin translocation as observed by immunofluorescence may be a simple and rapid method for assessing inhibition of cellular growth in response to differentiation inducers such as RA in cancer chemotherapy.

Cell Compartmentation↗

PubMed2006

Proteomic analysis of macrophages stimulated by lipopolysaccharide: Lipopolysaccharide inhibits the cleavage of nucleophosmin.

Lipopolysaccharide (LPS) is a complex glycolipid composed of a hydrophilic polysaccharide and a hydrophobic domain that is responsible for the biological activity of LPS. There are many reports about LPS stimulation, and many activated proteins have been detected after LPS stimulation in various cell types. Furthermore, most of the LPS signaling pathways are clear. However, we were interested in examining the changes of LPS-induced total cytosolic proteins expression and the LPS signaling pathway by the proteomics technique during LPS-induced macrophage activation. Our study employed two-dimensional gel electrophoresis and mass spectrometry to analyze the proteins involved in LPS-induced activation in RAW 264.7 cells. We found 11 protein spots whose expression was different between untreated cells and LPS-treated cells. Ten protein spots were identified, seven of which, tubulin beta-4 chain (49.6 kDa, pI 4.78), nucleophosmin (32.6 kDa, pI 4.62, two spots), 40S ribosomal protein SA (P40) (32.7 kDa, pI 4.74), transforming protein RhoA (21.8 kDa, pI 5.83), nucleolin (76.6 kDa, pI 4.69), and T-complex protein 1 zeta subunit (58 kDa, pI 6.63) were down-regulated, and three of which, nucleophosmin (32.6 kDa, pI 4.62, two spots) and proteosome subunit alpha type-1 (29.5 kDa, pI 6.00), were up-regulated. The suppression of the proteolytic degradation of nucleophosmin was associated with LPS-induced RAW 264.7 cell activation. Cleaved caspase-3 decreased, thus it might be involved in proteolysis of nucleophosmin in LPS-induced macrophage activation. Our study also demonstrated that there was no change of the expression of nucleophosmin at the mRNA level.

Animals↗

PubMed2005

Human histone chaperone nucleophosmin enhances acetylation-dependent chromatin transcription.

Histone chaperones are a group of proteins that aid in the dynamic chromatin organization during different cellular processes. Here, we report that the human histone chaperone nucleophosmin interacts with the core histones H3, H2B, and H4 but that this histone interaction is not sufficient to confer the chaperone activity. Significantly, nucleophosmin enhances the acetylation-dependent chromatin transcription and it becomes acetylated both in vitro and in vivo. Acetylation of nucleophosmin and the core histones was found to be essential for the enhancement of chromatin transcription. The acetylated NPM1 not only shows an increased affinity toward acetylated histones but also shows enhanced histone transfer ability. Presumably, nucleophosmin disrupts the nucleosomal structure in an acetylation-dependent manner, resulting in the transcriptional activation. These results establish nucleophosmin (NPM1) as a human histone chaperone that becomes acetylated, resulting in the enhancement of chromatin transcription.

Acetylation↗

PubMed1989

Cross-linkage of nucleophosmin in tumor cells by nitrogen mustard.

Mouse leukemia (P388) cells were incubated in cell culture medium containing nitrogen mustard [2-chloro-N-(2-chloroethyl)-N-methylethanamine] for 4 h. The nucleophosmin immunoband with a molecular weight of 37,000 (p37; other molecular weights are similarly designated) was observed in both control and nitrogen mustard-treated cells. Three additional immunobands with molecular weights of 80,000 (p80), 120,000 (p120), and 230,000 (p230) were identified in the drug-treated cells. The same results were observed with melphalan, but were not detected when mitomycin C, cis-platinum, Adriamycin, or actinomycin D were used. Treatments with DNase and RNase did not alter the molecular weights of these immunobands. These results indicate that the cross-linked products of nucleophosmin were not linked to DNA or RNA. The pI of p80, p120, and p230 is 5.1, which is the same as that of nucleophosmin (p37). The iodinated tryptic peptide map of p80 is identical to that of nucleophosmin. This result indicates that p80 is a dimer cross-linked by nitrogen mustard. The p80 and p120 immunobands were observed in Novikoff hepatoma and in hypertrophic rat liver, but were not detected in normal liver under the same conditions. These results indicate that tumor or proliferating cells have hexameric nucleophosmins which can be cross-linked by nitrogen mustards.

Animals↗

PubMed2005

Release of nucleophosmin from the nucleus: Involvement in aloe-emodin-induced human lung non small carcinoma cell apoptosis.

Aloe-emodin (1,8-dihydroxy-3-(hydroxymethyl)-anthraquinone) is one of the active constituents from the root and rhizome of Rheum palmatum. Our previous study has demonstrated that aloe-emodin induced a significant change in the expression of lung cancer cell apoptosis-related proteins compared to those of control cells. However, the molecular mechanisms underlying the biological effects of aloe-emodin still remain unknown. Based on these reasons, we were interested in the change of aloe-emodin-induced total protein expression by the proteomics technique during aloe-emodin-induced lung cancer cell apoptosis. Our study applied 2D electrophoresis to analyze the proteins involved in aloe-emodin-induced apoptosis in H460 cells. We found that the release of nucleophosmin from the nucleus to the cytosol and the degradation of nucleophosmin were associated with aloe-emodin-induced H460 cell apoptosis. Our study also demonstrated that the gene expression of nucleophosmin remained unchanged after treatment with aloe-emodin. The aloe-emodin-caused increase in the amount of proform and fragment of nucleophosmin in cytoplasm may be one of the important events for aloe-emodin-induced H460 cell apoptosis.

Amino Acid Sequence↗

PubMed1997

Npm3: a novel, widely expressed gene encoding a protein related to the molecular chaperones nucleoplasmin and nucleophosmin.

We report the cloning and initial characterization of the cDNAs, gene, and pseudogene of Npm3, a novel murine gene that encodes a protein related to the nuclear chaperone phosphoproteins, nucleoplasmin and nucleophosmin. Npm3 is located approximately 5 kb upstream of Fgf8 on mouse Chromosome 19 and consists of six exons spanning 2 kb. The first five exons code for an acidic protein of 19.0 kDa that contains a potential nuclear localization signal and potential phosphorylation sites for several kinases. Npm3 was expressed in all mouse tissues examined. On the basis of the similarity of Npm3 to nucleoplasmin and nucleophosmin in amino acid sequence, protein features, and exon structure, we propose that Npm3 is a new member of, and may share basic functions with, the nucleoplasmin/ nucleophosmin family of molecular chaperone proteins.

Amino Acid Sequence↗

PubMed2004

Nucleophosmin is a component of the fructoselysine-specific receptor in cell membranes of Mono Mac 6 and U937 monocyte-like cells.

The monocyte-like cell lines Mono Mac 6 (MM6) and U937 bind Amadori-modified proteins via fructoselysine (FL)-specific sites with molar masses of 110, 150 and 200 kDa, which can specifically be isolated by an affinity method with magnetobeads coated with glycated polylysine. Using Western blots developed with different anti-nucleophosmin antisera, MS-analysis and immunohistochemistry, we show that the nucleolar protein nucleophosmin is also localized in the cell membrane and is part of the 150- and 200-kDa membrane protein fractions of FL-specific binding membrane proteins. This is the first evidence that nucleophosmin is not only existing in the nucleolus and cytoplasm, but also, like nucleolin, is in the cell membrane.

Amino Acid Sequence↗

PubMed1996

Differential-display polymerase chain reaction identifies nucleophosmin as an estrogen-regulated gene in human vascular smooth muscle cells.

PURPOSE: Atheroprotective effects of estrogen (E2) are well documented and are due in part to direct effects of E2 on vascular cells. We recently demonstrated that human vascular smooth muscle cells (VSMCs) express a functional E2 receptor capable of activatine gene expression. This study was designed to identify E2-regulated genes in human VSMCs. METHODS: VSMC mRNA was screened by differential-display polymerase chain reaction (ddPCR) to identify E2-regulated genes. Quiescent human VSMCs were stimulated with 10% fetal bovine serum in the absence or presence of 10(-8) mol/L E2, and total cellular RNA was harvested. ddPCR was performed in triplicate on each RNA sample and differentially expressed candidate genes were isolated. Differential expression of candidate genes were confirmed by dot blotting and positive bands were identified by sequence analysis. E2-mediated regulation at the protein level was investigated by immunoblotting. RESULTS: ddPCR of RNA harvested from aortic VSMCs identified a 462 bp gene product, EAo8, as a candidate E2- regulated gene. Dot blotting with probes derived from four independent VSMC cultures demonstrated a 5.8 +/- 3.9-fold increase in EAo8 expression in response to E2 treatment (p < 0.05 vs control). Sequence analysis identified EAo8 as nucleophosmin, a nucleolar phosphprotein implicated in the regulation of cell growth and protein synthesis. E2-induced expression of nucleophosmin protein was demonstrated by immunoblotting in both saphenous vein and mammary artery VSMCs. CONCLUSIONS: E2 induces nucleophosmin expression in human VSMCs, and ddPCR is a useful approach for studying estrogen-regulated gene expression in VSMCs.

Cells, Cultured↗

PubMed1990

The major phosphorylation site of nucleophosmin (B23) is phosphorylated by a nuclear kinase II.

Nucleophosmin (B23) was phosphorylated in vitro with [gamma-32P]ATP and a nuclear kinase (type II) purified from HeLa cells. The phosphorylation was inhibited by heparin and by 2,3-diphosphoglycerate. Peptide mapping analysis indicated that the phosphorylation site in vitro was identical to that in vivo. Purified nucleoli have a similar kinase that phosphorylated nucleophosmin at the same site. These results indicated that nucleophosmin is phosphorylated in vivo by a nucleolar kinase (type II).

2,3-Diphosphoglycerate↗

PubMed1995

Differential expression of nucleophosmin and stathmin in human T lymphoblastic cell lines, CCRF-CEM and JURKAT analyzed by two-dimensional gel electrophoresis.

Two-dimensional gel electrophoresis was used to study the expression of intracellular proteins in adherent cells of human T lymphoblastic cell line, CCRF-CEM. The adherent cells grown in monolayer on a culture plate decreased the amount of proteins of M(r) 37,000 and pI 4.7-4.9, and of 17,000 and pI 5.7. The proteins were identified to be nucleophosmin for the 37,000 protein and stathmin for the 17,000 protein by microsequencing their CNBr fragments. The amount of proteins was increased in CCRF-CEM cells grown in floating mass to a comparable level of JURKAT cells which grew in floating mass throughout the culture. The adherent cells decreased their growth rate as compared with the cells in the floating mass. These results suggest that the adhesion of human T lymphoblastic cells modulates their morphology and proliferation via a concomitant decrease in the amount of nucleophosmin and stathmin.

Amino Acid Sequence↗

PubMed2001

Immunocytochemical localization of nucleophosmin and RH-II/Gu protein in nucleoli of HeLa cells after treatment with actinomycin D.

HeLa cells were studied with the use of light microscopical immunocytochemistry to obtain more information on the nucleolar localization of nucleophosmin (B23 protein) and RH-II/Gu protein. In control cells these proteins are colocalized. After structural rearrangement of nucleoli induced by actinomycin D, nucleophosmin was present in the nucleolar periphery and nucleolar peripheral caps. In contrast, RH-II/Gu protein was observed mainly in central regions of nucleoli as a compact body. However, in some nucleoli the proteins colocalized in a small portion of the peripheral nucleolar cap. The proteins were also colocalized in micronucleoli but occasionally RH-II/Gu protein was absent or both proteins were not present.

Cell Nucleolus↗

PubMed2002

Association of interferon regulatory factor-1, nucleophosmin, nuclear factor-kappaB, and cyclic AMP response element binding with acquired resistance to Faslodex (ICI 182,780).

To identify genes associated with survival from antiestrogens, both serial analysis of geneexpression and gene expression microarrays were used to explore the transcriptomes of antiestrogen-responsive (MCF7/LCC1) and -resistant variants(MCF7/LCC9) of the MCF-7 human breast cancer cell line. Structure of the gene microarray expression data was visualized at the top level using a novel algorithm that derives the first three principal components,fitted to the antiestrogen-resistant and -responsive gene expression data, from Fisher's information matrix. The differential regulation of several candidate genes was confirmed. Functional studies of the basal expression and endocrine regulation of transcriptional activation of implicated transcription factors were studied using promoter-reporter assays. The putative tumor suppressor interferon regulatory factor-1 is down-regulated in resistant cells, whereas its nucleolar phosphoprotein inhibitor nucleophosmin is up-regulated. Resistant cells also up-regulate the transcriptional activation of cyclic AMP response element (CRE) binding and nuclear factor kappaB (NFkappaB) while down-regulating epidermal growth factor receptor protein expression. Inhibition of NFkappaB activity by ICI 182,780 is lost in resistant cells, but CRE activity is not regulated by ICI 182,780 in either responsive or resistant cells. Parthenolide, a potent and specific inhibitor of NFkappaB, inhibits the anchorage-dependent proliferation of antiestrogen-resistant but not antiestrogen-responsive cells. This observation implies a greater reliance on their increased NFkappaB signaling for proliferation in cells that have survived prolonged exposure to ICI 182,780. These data from serial analysis of gene expression and gene microarray studies implicate changes in a novel signaling pathway, involving interferon regulatory factor-1, nucleophosmin, NFkappaB, and CRE binding in cell survival after antiestrogen exposure. Cells can up-regulate some estrogen-responsive genes while concurrently losing the ability of antiestrogens to regulate their expression. Signaling pathways that are not regulated by estrogens also can be up-regulated. Thus, some breast cancer cells may survive antiestrogen treatment by bypassing specific growth inhibitory signals induced by antagonist-occupied estrogen receptors.

Animals↗

PubMed1998

Nucleolar localization of the nucleophosmin-anaplastic lymphoma kinase is not required for malignant transformation.

The (2;5)(p23;q35) lymphoma-associated chromosomal translocation creates a novel fusion gene that incorporates parts of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase and nucleophosmin genes. We report here that the product of this fusion gene accumulates within the nucleoli of neoplastic cells, and that previous reports of a predominantly cytoplasmic localization for the protein represent a tissue-processing artifact. However, nucleolar accumulation of nucleophosmin-ALK may not be necessary for its oncogenic action, because an ALK protein expressed in a lymphoma carrying a variant (1;2) chromosomal translocation did not accumulate in nucleoli. Furthermore, an engineered hybrid TPR-ALK protein can transform rodent fibroblasts and produce lymphomas in mice while remaining confined to the cytoplasm. We propose that the transforming action of ALK may not be reliant on its nucleolar localization, a hypothesis that may have implications for studies of other proteins involved in oncogenesis that are relocalized after the creation of fusion genes.

Anaplastic Lymphoma Kinase↗