• 대한약리학회지
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• 제31권2호
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• pp.241-250
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• 1995

Protein B23 is one of the major nucleolar phosphoproteins associated with pre-ribosomal particles, and is localized in the granular region of the nucleolus. Recent studies suggest that protein B23 shuttles between nucleus and cytoplasm and also interacts with HIV Rev. These findings indicate that protein B23 is important in nucleocytoplasmic relationship and viral replication. However, the exact function of protein B23 is not clear yet. In acute nucleolar hypertrophy of rat liver, treated with thioacetamide, there was observed an increase of not only protein B23 but also B23-like protein p45 when anti-B23 monoclonal antibody (MAb) was used for identification. On the basis of the large B23 specific epitope structure composed of 68 amino acids, a hypothesis was formulated to examine that p45 is the pre-B23 resulting from excessive production of B23. In an attempt to investigate the precursor of B23, we analyzed the subcellular fractions and microsomal subfractions. Subsequently, we analyzed the finger printings of B23-like proteins using the tryptic peptide mapping. The results are summarized: 1) Using B23 MAb, we observed the presence of B23-like proteins in nucleolar fraction, nucleoplasmic fraction and microsomal fraction. 2) In the further microsomal subfractionation, we could partially purify B23-like protein in 2M layer of sucrose gradient. 3) When ion exchange chromatography was employed, there were protein species 80kDa(p80), 65kDa(p65) and 60kDa(p60). 4) Based on the tryptic map analysis of $^{125}I$ labeled proteins, the similarity between B23 and p80 was found only in 9 out of 14(B23) and 21(p80) peptides, and difference was found in the remaining peptides. p80 and p60 had 18 common peptides, and all the peptides of p60 were similar to those of p80. From these results, it is proposed that p45 is an abnormal metabolite resulting from carcinogenesis by thioacetamide, and it is not the precursor of B23. In addition, we suggest that p80 may be a precursor of p45.

• Parasites, Hosts and Diseases
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• 제45권3호
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• pp.165-174
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• 2007

Toxoplasma gondii GRA10 expressed as a GFP-GRA10 fusion protein in HeLa cells moved to the nucleoli within the nucleus rapidly and entirely. GRA10 was concentrated specifically in the dense fibrillar component of the nucleolus morphologically by the overlap of GFP-GRA10 transfection image with IFA images by monoclonal antibodies against GRA10 (Tg378), B23 (nucleophosmin) and C23 (nucleolin). The nucleolar translocalization of GRA10 was caused by a putative nucleolar localizing sequence (NoLS) of GRA10. Interaction of GRA10 with TATA-binding protein associated factor 1B (TAF1B) in the yeast two-hybrid technique was confirmed by GST pull-down assay and immunoprecipitation assay. GRA10 and TAF1B were also co-localized in the nucleolus after co-transfection. The nucleolar condensation of GRA10 was affected by actinomycin D. Expressed GFP-GRA10 was evenly distributed over the nucleoplasm and the nucleolar locations remained as hollows in the nucleoplasm under a low dose of actinomycin D. Nucleolar localizing and interacting of GRA10 with TAF1B suggested the participation of GRA10 in rRNA synthesis of host cells to favor the parasitism of T. gondii.

• 생명과학회지
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• 제19권4호
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• pp.436-441
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• 2009

B23/nucleophosmin은 핵인 단백질로서 외부 스트레스에 의해 핵인에서 핵으로 이동하게 된다. 이러한 세포 내 위치변화는 MDM2에 의한 p53단백질의 안정화에 영향을 미친다. 노화세포는 거대한 단일 핵인을 가지고 있으며, 외부 스트레스에 의해 p53 안정성이 감소한다. 그렇지만, 노화세포에서 어떠한 기전에 의해 p53의 불안정성이 증가하는 지는 아직 밝혀진 바가 없다. 따라서 본 연구에서는 노화세포에서 B23/nucleophosmin과 p53간의 상호 관련성을 조사하여 p53 안정성에 미치는 영향을 규명하고자 하였다. 본 연구에서는 IMR90세포주에 ras oncogene을 과발현시켜 노화세포를 유도하였다. 핵인 스트레스에 의해 노화세포 내 p53 단백질 발현은 감소하였으나, B23/nucleophosmin 단백질의 발현은 정상세포와 큰 차이가 없었다. 그렇지만, 두 단백질의 세포 내 위치는 노화세포에서 변화가 있었다. 즉, 정상세포와 달리, 노화세포에서는 스트레스에 의해 핵 내 p53발현이 증가하지 않았으며, B23/nucleophosmin은 핵 내로 이동하지 않고, 핵인에 그대로 머물러 있었다. 노화세포에서 MDM2와 p53간 상호결합이 안정적으로 유지된대 비하여, p53과 B23/nucleophosmin간의 상호결합은 감소하였다. 이러한 결과는 노화세포에서 핵인 스트레스에 의한 p53단백질의 안정성은 B23/nucleophosmin 결합이 감소하여 일어나는 것으로 해석된다.

• BMB Reports
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• 제41권12호
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• pp.840-845
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• 2008

Nucleophosmin/B23, a major nucleolar phosphoprotein, is overexpressed in actively proliferating cells. In this study, we demonstrate that B23 exclusively localizes in the nucleolus, whereas ATP depletion results in the redistribution of B23 throughout the whole nucleus and destabilizes B23 via caspase-3 mediated cleavage. Interestingly, ATP binding precedes PI(3,4,5)P3 binding at lysine 263 and ATP binding mutants fail to restore the anti-apoptotic functions of B23 in PC12 cells. Thus, the ATP-B23 interaction is required for the stability of the B23 protein and regulates cell survival, confining B23 within the nucleolus in PC12 cells.

• 대한약리학회지
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• 제32권3호
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• pp.399-406
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• 1996

Thioacetamide는 non-genotoxic 발암제로서 세포단백의 변형을 초래하는 것으로 알려져 있으며 이것을 단기간 처리하면 핵소체의 비대를 초래하게 된다. 본 연구에서는 thioacetamide를 처리한 간세포를 in vivo와 in vitro 상태에서 관찰하였다. In vivo상태로서 thioacetamide를 쥐의 복강에 7일간 주사하면 (50mg/kg), 핵소체 비대와 B23 및 MAP kinase와 같은 신호전달분자들이 증가하는 것을 관찰할 수 있었다. In vitro 상태로서 쥐의 간장을 collagenase로 분리하여 유전자 치료에 사용될 수 있는 배양조건으로 간세포를 배양하여 핵소체를 관찰한 결과 핵소체 비대가 현저하였으며, B23의 양도 증가하였다. 본 실험의 결과로 미루어 볼 때, 간세포는 핵소체 비대 수용능력이 약 100배 이상이라고 할 수 있으며, thioacetamide 처리에 의하여 라이보좀 생성과 핵소체 증가 능력이 증폭되어 나타나는 것으로 사료된다.

• Journal of Radiation Protection and Research
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• 제30권4호
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• pp.197-208
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• 2005

Although little information is available on the underlying mechanisms, various genetic factors have been associated with tissue-specific responses to radiation. In the present study, we explored the possibility whether organ specific gene expression is associated with radiosensitivity using samples from brain, lung and spleen. We examined intrinsic expression pattern of 23 genes in the organs by semi-quantitative RT-PCR method using both male and female C57BL/6 mice. Expression of p53 and p21, well known factors for governing sensitivity to radiation or chemotherapeutic agents, was not different among the organ types. Both higher expression of sialyltransferase, delta7-sterol reductase, leptin receptor splice variant form 12.1, and Cu/Zn superoxide dismutase (SOD) and lower expression of alphaB crystalline were specific for spleen tissue. Expression level of glutathione peroxidase and APO-1 cell surface antigen gene in lung tissue was high, while that of Na, K-ATPase alpha-subunit, Cu/ZnSOD, and cyclin G was low. Brain, radioresistant organ, showed higher expressions of Na, K-ATPase-subunit, cyclin G, and nucleolar protein hNop56 and lower expression of delta7-sterol reductase. The result revealed a potential correlation between gene expression patterns and organ sensitivity, and Identified genes which might be responsible for organ sensitivity.