BACKGROUND: BRCA1 (breast-cancer gene 1) is a tumor suppressor gene that accounts for nearly all families of both early onset breast and ovarian cancer and about 45% of families with breast cancer only. Sporadic nonhereditary breast cancer is recognized as the most common form of this malignancy. However, presence of germ-line mutations in the BRCA1 gene of these tumors is an infrequent event. The BRCA1 protein includes a ring domain and an acidic domain, both of which are characteristics of certain transcription factors, as well as two putative nuclear localization signals (NLS) that interact with importin-alpha. The normal BRCA1 protein is located in the nucleus of most breast-cell types whereas the BRCA1 protein of breast cancer cells is aberrantly localized in the cytoplasm. This mislocation of the BRCA1 protein in breast cancer cells may be due to defects in the NLS receptor-mediated pathway for the nuclear import of the BRCA1 gene product. Identification of importin-alpha mutations as a cellular protein responsible for the nuclear import of BRCA1 in breast-cancer cell lines and primary breast cancers is the focus of this investigation. METHODS: A series of 15 surgical samples of breast cancer and 3 samples of breast-cancer cell lines (Hs578T, ZR75-1, MCF-7) was assayed for the presence of the deletion mutant in importin-alpha by using both RT-PCR amplification of importin-alpha transcripts and sequencing analysis. RESULTS: Three of the 15 primary breast cancers and 1 of the 3 breast-cancer cell lines showing deletions in importin-alpha transcripts produced two different truncated transcripts. 1208 bp deletions were observed in transcripts from breast cancer (T-1, T-3) and ZR75-1, which is specified by the nucleotide 251-1458 of the transcript. Another transcript encoded by primary breast cancer (T-2) included a 1312 bp deletion in the nucleotide 61-1372 of the transcript. CONCLUSIONS: The deletions eliminated part of the importin-alpha transcript segment encoding the putative NLS-binding domain but not the importin-beta binding domain, suggesting that these deletion mutants could not bind to NLS of the BRCA1 protein. These results suggest that the composite effects of mislocationof the BRCA1 protein by deletion of the NLS-binding domain in importin-alpha may contribute to tumorigenesis in sporadic breast cancer.
Active Transport, Cell Nucleus ; alpha Karyopherins* ; Alternative Splicing ; beta Karyopherins ; BRCA1 Protein ; Breast Neoplasms* ; Breast* ; Carcinogenesis ; Cell Line ; Cytoplasm ; Genes, BRCA1 ; Genes, Tumor Suppressor ; Germ-Line Mutation ; Humans ; Nuclear Localization Signals ; Ovarian Neoplasms ; Transcription Factors

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 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

OBJECTIVE: To clone 5' untranslated region of human IPO8 gene and determine its transcription activity. METHODS: We used 5' rapid amplification of cDNA ends (RACE) analysis to identify the IPO8 transcription start site (TSS), and amplified series truncated 5' UTR fragment containing transcription start site. The PCR productions were inserted into luciferase report vector pGL3- Basic. After confirmation by restriction enzyme digestion, the recombinant plasmids were cotransfected into Saos-2 cells with plasmid pRL-TK. The luciferase activities were measured by dual luciferase reporter system. RESULTS: The IPO8 gene transcription start site was established. The electrophoresis analysis of restriction enzyme digestion and DNA sequencing verified the fragments were successfully amplified and inserted into pGL3-Basic. After the recombinant plasmids transfected, the highexpressions of luciferase were detected in Saos-2 cells. CONCLUSION The recombinant vector containing IPO8 promoter is constructed successfully, which provides a foundation for determining expressional regulation of IPO8 in the further study.
Cloning, Molecular ; DNA, Complementary ; Genetic Vectors ; Humans ; Luciferases ; Plasmids ; Promoter Regions, Genetic ; Transfection ; beta Karyopherins ; genetics

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

OBJECTIVETo reconfirm the association of KPNB3 with schizophrenia in Chinese population.

METHODSTwo single nucleotide polymorphisms (SNPs), rs2588014 and rs626716 at the KPNB3 locus, were genotyped in 304 Chinese Han family trios consisting of fathers, mothers, and affected offsprings with schizophrenia. These 2 SNPs were detected by PCR-based restriction fragment length polymorphism (RFLP) analysis. The Hardy-Weinberg equilibrium for genotypic distributions was estimated by the goodness-of-fit test. The UNPHASED program was used to perform transmission disequilibrium test (TDT), haplotype analysis, and pair-wise measure of linkage disequilibrium (LD) between these 2 SNPs.

RESULTSThe genotypic distributions of both rs2588014 and rs626716 were in the Hardy-Weinberg equilibrium (P > 0.05). The TDT revealed allelic association with rs626716 (chi2 = 9.31, P = 0.0023) but not with rs2588014 (chi2 = 3.44, P = 0.064). The global P-value was 0.0099 for 100 permutations. The haplotype analysis also showed a disease association (chi2 = 25.97, df = 3, P = 0.0000097).

CONCLUSIONThe present study provides further evidence in support of the KPNB3 association with schizophrenia in Chinese population.

Adult ; China ; epidemiology ; Female ; Genetic Predisposition to Disease ; Genotype ; Humans ; Male ; Polymorphism, Single Nucleotide ; Schizophrenia ; epidemiology ; genetics ; beta Karyopherins ; genetics

OBJECTIVE: To explore the genetic basis for a neonate featuring developmental delay. METHODS: Clinical examination and laboratory tests were carried out for the patient. Peripheral venous blood samples of the proband and his parents were extracted and subjected to target capture next generation sequencing. Candidate variant was verified by Sanger sequencing. RESULTS: The patient, a four-month-old male, has presented with developmental delay and weakness of limbs. Genetic testing revealed that he had harbored a novel c.1432C>T variant of the TNPO3 gene, which was inherited from his mother. The nonsense variant has resulted in premature termination of protein translation and was predicted to be pathogenic by bioinformatics analysis. CONCLUSION The heterozygous c.1432C>T variant of the TNPO3 gene probably underlay the limb-girdle muscular dystrophies form 1F in this patient. Above finding has enriched the variation spectrum of the TNPO3 gene.
Genetic Testing ; Heterozygote ; High-Throughput Nucleotide Sequencing ; Humans ; Infant ; Male ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation ; Phenotype ; beta Karyopherins/genetics*

Active Transport, Cell Nucleus ; physiology ; Animals ; Cell Nucleus ; physiology ; Cilia ; physiology ; Humans ; Molecular Motor Proteins ; physiology ; beta Karyopherins ; physiology ; ran GTP-Binding Protein ; physiology

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

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