OBJECTIVE: To explore the expression and clinical significance of XPO1 in newly diagnosed adult diffuse large B-cell lymphoma (DLBCL), and further investigate its functional mechanism. METHODS: Immunohistochemical testing was conducted for XPO1 expression in 93 cases of DLBCL and 30 cases of reactive lymphoid hyperplasia. A risk model was construed to find survival related genes in DLBCL patients. Cell proliferation, apoptosis, and cell cycle assays were performed to explore the effect of XPO1 inhibitor (KPT-8602) and XPO1 knockdown. Differential expression gene (DEG) was examined based on the transcriptomes. RESULTS The expression of XPO1 in DLBCL patients was higher than that of the controls. Compared with XPO1 low-expression group, XPO1 high-expression group had a worse prognosis. The constructed risk model indicated that XPO1 and 14 genes in nucleocytoplasmic transport pathway (NTP) might be potential prediction marker of adverse outcome in DLBCL. Moreover, KPT-8602 as well as the XPO1 knockdown could inhibit cell proliferation, promote apoptosis, and induce cell cycle arrest in two DLBCL cell lines, Farage and SU-DHL-4. Based on the gene expression profiling in the datasets of DLBCL, patients were classified into XPO1 high and XPO1 low expression groups, and the MYBL1 was identified as the down-stream effector of XPO1. Inhibiting the function of XPO1 or reducing its expression can significantly decrease the expression of MYBL1 Conclusion: XPO1 is highly expressed in DLBCL, which is associated with poor prognosis. The oncogenic roles of the new XPO1/MYBL1 signaling are identified in DLBCL and XPO1 inhibitor may be a potential option for newly-diagnosed DLBCL patients.
Humans ; Lymphoma, Large B-Cell, Diffuse/pathology* ; Exportin 1 Protein ; Karyopherins/metabolism* ; Receptors, Cytoplasmic and Nuclear/metabolism* ; Cell Proliferation ; Apoptosis ; Prognosis ; Cell Line, Tumor ; Clinical Relevance

Bombyx mori nucleopolyhedrovirus (BmNPV) is extremely harmful to the silk industry. The polyhedrin, which encodes the polyhedrin (Polh), can be expressed at ultra-high levels and form occlusion bodies in the nucleus, embedding the progeny virus within it. However, the detailed mechanism by which polyhedrin is transported into the host cell nucleus remains unknown. Clarifying the nuclear import mechanisms of viral proteins can help us develop better prevention and treatment measures against baculoviruses. This study employed molecular cloning, co-immunoprecipitation, and immunofluorescence to analyze in detail the expression pattern of the highly expressed polyhedrin in the very late stage of the virus, and further revealed that the host protein importin α participates in the nuclear import of polyhedrin through protein interactions. This study provides a reference for further elucidating the nuclear import mechanisms of the baculovirus proteins including polyhedrin that can enter the nucleus.
Nucleopolyhedroviruses/metabolism* ; Active Transport, Cell Nucleus ; Animals ; Bombyx/virology* ; alpha Karyopherins/metabolism* ; Cell Nucleus/metabolism* ; Viral Structural Proteins/metabolism* ; Occlusion Body Matrix Proteins

Hypoxia-inducible factor 1 (HIF1) is a master transcription factor that induces the transcription of genes involved in the metabolism and behavior of stem cells. HIF1-mediated adaptation to hypoxia is required to maintain the pluripotency and survival of stem cells under hypoxic conditions. HIF1 activity is well known to be tightly controlled by the alpha subunit of HIF1 (HIF1α). Understanding the regulatory mechanisms that control HIF1 activity in stem cells will provide novel insights into stem cell biology under hypoxia. Recent research has unraveled the mechanistic details of HIF1α regulating processes, suggesting new strategies for regulating stem cells. This review summarizes recent experimental studies on the role of several regulatory factors (including calcium, 2-oxoglutarate-dependent dioxygenase, microtubule network, importin, and coactivators) in regulating HIF1α activity in stem cells.
Anoxia ; Biology ; Calcium ; Hypoxia-Inducible Factor 1 ; Karyopherins ; Metabolism ; Microtubules ; Stem Cells ; Transcription Factors

MicroRNAs (miRNAs) are conserved small non-coding RNAs that play an important role in the regulation of gene expression and participate in a variety of biological processes. The biogenesis of miRNAs is tightly controlled at multiple steps, such as transcription of miRNA genes, processing by Drosha and Dicer, and transportation of precursor miRNAs (pre-miRNAs) from the nucleus to the cytoplasm by exportin-5 (XPO5). Given the critical role of nuclear export of pre-miRNAs in miRNA biogenesis, any alterations of XPO5, resulting from either genetic mutation, epigenetic change, abnormal expression level or posttranslational modification, could affect miRNA expression and thus have profound effects on tumorigenesis. Importantly, XPO5 phosphorylation by ERK kinase and its cis/trans isomerization by the prolyl isomerase Pin1 impair XPO5's nucleo-to-cytoplasmic transport ability of pre-miRNAs, leading to downregulation of mature miRNAs in hepatocellular carcinoma. In this review, we focus on how XPO5 transports pre-miRNAs in the cells and summarize the dysregulation of XPO5 in human tumors.
Carcinoma, Hepatocellular ; genetics ; metabolism ; Cell Nucleus ; metabolism ; Cytoplasm ; metabolism ; Humans ; Karyopherins ; chemistry ; metabolism ; physiology ; Liver Neoplasms ; genetics ; metabolism ; MicroRNAs ; chemistry ; metabolism ; NIMA-Interacting Peptidylprolyl Isomerase ; Neoplasms ; genetics ; metabolism ; RNA Precursors ; chemistry ; metabolism ; RNA Transport

High expression of Fightless I (FLII) is associated to multiple tumors. Based on our previous study that FLII might be involved in the nuclear export, we assessed the possible interaction of FLII with the nuclear envelop associating proteins Importin β and Nup88. We first constructed GST-FLII, GST-LRR recombinant plasmids and transformed them into the Rosetta strain to produce GST-FLII, GST-LRR fusion protein. After purification of these proteins, GST-pull down, as well as co-immunoprecipitation, were used to test the interaction of FLII with Importin β and Nup88. FLII interacted with Importin β and Nup88, and FLII LRR domain is responsible for these interactions. Thus, FLII may play a role in nuclear export through interaction with Importin β and Nup88.
Humans ; Microfilament Proteins ; metabolism ; Nuclear Pore Complex Proteins ; metabolism ; Receptors, Cytoplasmic and Nuclear ; metabolism ; Recombinant Fusion Proteins ; metabolism ; beta Karyopherins ; metabolism

Bel1, a transactivator of prototype foamy virus (PFV), plays pivotal roles in the replication of PFV. Previous studies have shown that Bel1 bears a nuclear localization signal (NLS), but its amino acid sequence remains unclear and the corresponding importins have not been identified. In this report, we inserted various fragments of Bel1 into an EGFP-GST fusion protein and investigated their subcellular localization by fluorescence microscopy. We found that the 215PRQKRPR221 fragment could direct nuclear localization, which accords with the consensus sequence K(K/R)X(K/R) of monopartite NLS. Point mutation experiments revealed that K218, R219, and R221 are essential for the nuclear localization of Bel1. The results of the GST-pulldown showed that the Bel1 fragment with residues 215-223, which bears the NLS, interacts with KPNA1, KPNA6, and KPNA7. This result suggests that KPNA1, KPNA6, and KPNA7 maybe involved in Bel1 nuclear translocation.
Cell Line ; Cell Nucleus ; genetics ; metabolism ; virology ; Humans ; Nuclear Localization Signals ; genetics ; metabolism ; Protein Binding ; Protein Transport ; Retroviridae Infections ; genetics ; metabolism ; virology ; Retroviridae Proteins ; chemistry ; genetics ; metabolism ; Spumavirus ; chemistry ; genetics ; physiology ; Trans-Activators ; chemistry ; genetics ; metabolism ; alpha Karyopherins ; genetics ; metabolism

OBJECTIVETo observe the variations of intracellular localization and expression of importin 8 (IPO8) during osteoblast differentiation.

METHODSAlizarin red staining, immunocytochemistry and real-time PCR were employed to examine the changes in the intracellular localization and expression of IPO8 mRNA during induced osteogenic differentiation of human osteoblast-like SaOS-2 cells.

RESULTSNumerous red mineralized nodules were observed on day 10 in the induced cells with alizarin red staining. Immunocytochemical staining showed that IPO8 immunoreactivity was the strongest in the perinuclear cytoplasm of the cells. On day 3 of osteoblast differentiation, IPO8 immunoreactivity in the cell nuclei became stronger. On day 7, IPO8 was located mainly in the nuclei, and on day 10 the cells were osteocyte-like and IPO8 was distributed in the cytoplasm. Real-time PCR showed a significantly increased expression of OPN mRNA during osteoblast differentiation, and the expression level of IPO8 mRNA was the highest on day 3 and declined on days 7 and 10.

CONCLUSIONThe intracellular localization and expression level of IPO8 undergo significant changes during osteogenesis, indicating its role in regulating osteoblast differentiation.

Cell Differentiation ; Cell Line ; Humans ; Osteoblasts ; cytology ; metabolism ; Osteogenesis ; beta Karyopherins ; metabolism

The HIV-1 Rev protein facilitates nuclear export of unspliced and singly spliced viral transcripts containing RRE RNA through the CRM1 export pathway. Inhibition of Rev-mediated RNA nuclear export can arrest HIV-1 transcriptional process, which clearly, reveals a target for anti-HIV drug development. In this work, a cell-based assay has been established for screening anti-HIV compounds targeting the Rev-mediated RNA nuclear export. This assay utilized a codon-optimized green fluorescent protein (GFP) as reporter gene, which expression is in a Rev-dependent manner. Any compound that inhibits the Rev-mediated RNA nuclear export is identified by reducing emission of GFP. The Z' score of this model is 0.8220. Three thousands compounds were screened and the positive rate was 9.3% with a cutoff at 50% inhibition. IMB7C7, one of the positive compounds, efficiently inhibits viral production from HIV-1 infected cells.
Active Transport, Cell Nucleus ; drug effects ; Anti-HIV Agents ; pharmacology ; Cell Nucleus ; metabolism ; Codon ; Fatty Acids, Unsaturated ; pharmacology ; Genes, Reporter ; Green Fluorescent Proteins ; genetics ; metabolism ; HEK293 Cells ; HIV-1 ; drug effects ; genetics ; High-Throughput Screening Assays ; Humans ; Karyopherins ; genetics ; metabolism ; RNA, Viral ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Transfection ; Virus Replication ; drug effects ; rev Gene Products, Human Immunodeficiency Virus ; genetics ; metabolism

PURPOSE: IRF-5 is a direct transducer of virus-mediated and TLR-mediated signaling pathways for the expression of cytokines and chemokines which form homodimers or heterodimers with IRF-7. However, direct IRF-5-specific monoclonal antibodies (mAbs) are not available at present. These could be used to further evaluate the functions of IRF-5. In this study, we produced and characterized three mouse mAbs to human IRF-5. The binding of IRF-5 to nuclear import proteins was first identified using a mAb. MATERIALS AND METHODS: His-tagged human IRF-5 protein spanning amino acid residues 193- 257 was used as an antigen and three mAbs were produced. The mAbs were tested with ELISA, Western blot analysis (WB), immunofluorescent staining (IF), and immunoprecipitation (IP). In addition, the nuclear import protein which carried phosphorylated IRF-5 was identified using one of these mAbs. RESULTS: MAbs 5IRF8, 5IRF10 and 5IRF24 which reacted with the recombinant His-IRF-5(193-257) protein were produced. All mAbs bound to human IRF-5, but not to IRF-3 or IRF-7. They could be used for WB, IF, and IP studies. The binding of phosphorylated IRF-5 to karyopherin-alpha1 and -beta1 was also identified. CONCLUSION: Human IRF-5-specific mAbs are produced for studying the immunologic roles related to IRF-5. Phosphorylated IRF-5 is transported to the nucleus by binding to nuclear import proteins karyopherin-alpha1 and -beta1.
Animals ; *Antibodies, Monoclonal ; Base Sequence ; Cell Line ; Cross Reactions ; DNA Primers/genetics ; Humans ; Interferon Regulatory Factors/genetics/*immunology/*metabolism ; Mice ; Mice, Inbred BALB C ; NIH 3T3 Cells ; Protein Binding ; Recombinant Proteins/genetics/immunology/metabolism ; alpha Karyopherins/*metabolism ; beta Karyopherins/*metabolism

OBJECTIVETo investigate the expression and relationship of p27(kip1) and its related molecules Jab1 and CRM1 during proliferation of lymphoma cells U937.

METHODSU937 cells were treated with serum starvation and release, and the effects of these treatments on the cell growth was tested with cell number counting. The expression and localization of p27(kip1), Jab1 and CRM1 in U937 cells were detected by Western blot, double immunolabelling and laser scanning confocal microscopy.

RESULTSThe growth of U937 cells was blocked by serum starvation. The total protein of p27(kip1) was increased while Ser10-phosphorylated p27(kip1) -related molecules Jab1 and CRM1 were decreased. Meanwhile, the location of p27(kip1) was changed from cytoplasm into nuclei. After serum release, the location of p27(kip1) expression reappeared in the cytoplasm again.

CONCLUSIONDuring the proliferation process of lymphoma U937 cells, Jab1 and CRM1 may influence the location and expression of p27kip1, and may participate in regulation of growth of NHL cells.

COP9 Signalosome Complex ; Cell Culture Techniques ; Cell Nucleus ; metabolism ; Cell Proliferation ; Culture Media, Serum-Free ; pharmacology ; Cyclin-Dependent Kinase Inhibitor p27 ; metabolism ; Cytoplasm ; metabolism ; Humans ; Intracellular Signaling Peptides and Proteins ; metabolism ; Karyopherins ; metabolism ; Peptide Hydrolases ; metabolism ; Receptors, Cytoplasmic and Nuclear ; metabolism ; U937 Cells