Foamy virus can establish lifelong persistent infection in mammal hosts without inducing diseases. Such special characteristic stimulates the interests of researchers. As reported, the accessory protein Bet of foamy virus could regulate the gene expression and infection cycle of foamy virus and take part in the generation of chronic viral infection. And also, Bet might prevent the host cellular defense factor APO-BEC3 from interfering the replication of virus and play a role in maintaining viral persistent infection. In order to elucidate the roles of Bet in the foamy virus replication and infection, this review summarized the research progress of Bet protein reported in recent years.
Animals ; Gene Expression Regulation, Viral ; Humans ; Retroviridae Infections ; immunology ; virology ; Retroviridae Proteins ; genetics ; metabolism ; Spumavirus ; genetics ; metabolism

Carrier Proteins ; metabolism ; physiology ; HIV-1 ; physiology ; Models, Biological ; Proteins ; metabolism ; physiology ; Retroviridae Infections ; virology

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

Transgene silencing is one of two major obstacles in both basic biomedical research for transgene and clinical practice of gene therapy. Based on the model of HT1080 cell clones, which transduced single copy of retroviral vector MGPN2, the mechanism of transgene silencing was explored in this investigation by a serial molecular techniques. In the HT1080 cell clone that absence of GFP protein synthesized, no significant aberration of epigenetic modification was detected, but the transcript size and the sequence changed that resulted in the reading frame shift. In addition to chromosomal position effect leading to transgene silencing, the transcript reading frame shift associated with retroviral vector rearrangements could induce complete silencing of transgene.
Cell Line, Tumor ; Gene Rearrangement ; Gene Silencing ; physiology ; Genetic Engineering ; Genetic Vectors ; genetics ; Humans ; Retroviridae ; genetics ; metabolism ; Transgenes ; genetics

To elucidate the effect of established primary bone marrow stromal layers on the gene transduction of human hematopoietic stem/progenitor cells (HSC/HPC), mononuclear cells (MNC) from adult bone marrow were isolated by centrifugation on Ficoll-Hypaque gradients and plated in stromal culture medium. The cells were incubated until passage 4 to establish primary stromal layers. The HSC/HPC prestimulated by cytokines were transduced by retroviral supernatant containing mdr1 gene in presence of irradiated stroma-contact support. Transduced cells were plated in a colony-forming unit assay with and without vincristine (VCR) to assess the efficiency of transduction. Individual colonies were also analyzed by polymerase chain reaction (PCR) for the presence of provirus. The results showed that the mixed adherent cell layers were formed when adult bone marrow stromal cells were incubated for four to six weeks, mainly being composed of fibroblasts. In the presence of stroma-contact support, the average of gene transduction efficiency in marrow-derived progenitors increased 2.1 to 3.3 folds measured by colony-forming assay and/or PCR, significantly higher than those without support of stroma. It is concluded that the presence of bone marrow stroma support in combination with cytokine facilitates augmenting the extent of retroviral-mediated gene transduction.
Bone Marrow Cells ; physiology ; Genes, MDR ; Hematopoietic Stem Cells ; metabolism ; Humans ; Retroviridae ; genetics ; Stromal Cells ; physiology ; Transduction, Genetic

OBJECTIVETo investigate the relationship between retroviruses and autoimmune diseases, to clone the novel retroviral NP9 gene from human endogenous retrovirus (HERV), and to construct its expression vector.

METHODSThe viral NP9 gene was amplified and cloned by RT-PCR and T-A clone techniques, and its sequence was determined with Perkin-Elmer 377 DNA Sequencer. The amplified viral NP9 gene was subcloned into the prokaryotic express vector pQE30. The recombinant plasmids were identified by restriction endonuclease digestion and sequencing. The recombinant pQE30-NP9 protein was expressed in M15 host cells under the IPTG induction and showed with SDS-PAGE,and the corresponding NP9 viral protein was identified with Western blot analysis.

RESULTA specific band of 250 bp was amplified using RT-PCR from total RNA of peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE) and confirmed as the NP9 gene via T-A clone and DNA sequencing analyses. SDS-PAGE profile showed a clear protein band with a relative molecular weight 9 kD in the IPTG-induced samples, which was confirmed as viral NP9 protein by Western blot analysis.

CONCLUSIONThe NP9 gene has been successfully isolated and cloned from PBMCs of SLE patients and the corresponding NP9 viral protein expressed in prokaryotic expression vector.

Amino Acid Sequence ; Base Sequence ; Cloning, Molecular ; Gene Products, env ; biosynthesis ; genetics ; Genetic Vectors ; Humans ; Lupus Erythematosus, Systemic ; genetics ; virology ; Molecular Sequence Data ; Retroviridae ; genetics ; metabolism ; Retroviridae Proteins ; biosynthesis ; genetics

OBJECTIVETo construct the retroviral vector containing human micro-dystrophin gene and detect the expression of human micro-dystrophin in mdx mice bone marrow-derived mesenchymal stem cells (MSCs) after retrovirus infection.

METHODSRetroviral vector for micro-dystrophin gene was constructed and transferred into the packing cell PA317 mediated by Lipofectamine 2000. The retroviral supernatant containing the target genes were subsequently used to infect mdx mice MSCs. Micro-dystrophin expression was examined by methods of immunofluorescence staining and reverse transcriptase-polymerase chain reaction.

RESULTSMicro-dystrophin retroviral vector was successfully constructed and transferred into PA317 cells, and 48 h after infection with the recombinant retrovirus in mdx mice MSCs, 319 bp fragment could be detected by electrophoresis in the RT-PCR products. The red particles could be detected in some infected mdx mice MSCs with immunofluorescence staining. CONCLUSION mdx mice MSCs infected with retrovirus containing micro-dystrophin gene can express micro-dystrophin protein.

Animals ; Bone Marrow Cells ; cytology ; metabolism ; Dystrophin ; biosynthesis ; genetics ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Mice ; Mice, Inbred mdx ; Muscular Dystrophy, Animal ; metabolism ; Retroviridae Infections ; Transfection

This study was purpose to establish the transgenic mouse models of the truncated platelet integrin β3 by retrovirus-infected hematopoietic stem cells (HSCs) transplantation and to provide the basis for further study of the role of integrin β3 cytoplasmic domain in platelet bi-directional signaling pathways. Wild-type β3, β3-Δ759 (R(760) GT(762) truncated β3) and β3-Δ754 (T(755) NITYRGT(762) truncated β3) cDNAs were subcloned into MSCV MigR1 retroviral vector bearing a GFP gene and packaged into infective retrovirus with BOSC23 cell strain. The bone marrow HSCs of the β3 deficient mice were infected by the retroviruses, and transplanted into lethally-irradiated wild type C57BL/6 mice. GFP positive rate and surface β3 expression of the recipients' platelets at 6 to 8 weeks after transplantation were detected by flow cytometry to evaluate the transgenic efficiency. The results showed that four kinds of transgenic mouse models including vector, wild-type β3, β3-Δ759 and β3-Δ754 were established successfully. GFP positive rates of transgenic mouse platelets ranged from 18% to 66% and the β3 expression of transgenic mouse reached heterozygote (β3(+/-) level of mouse). It is concluded that establishment of transgenic mouse models mediated by retrovirus-infected HSCs transplantation is a feasible, fast, and high throughput transgenic approach and laid a solid foundation for further research on the role of integrin β3 cytoplasmic domain for bi-directional signaling of platelets in vivo, and for the gene therapy of platelet disorders.
Animals ; Blood Platelets ; metabolism ; Genetic Vectors ; Hematopoietic Stem Cell Transplantation ; Integrin beta3 ; metabolism ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Retroviridae ; genetics

OBJECTIVETo investigate the inhibition of telomerase activity and cellular proliferation in tongue cancer TCCA-8113 cell lines by antisense human tankyrase-1 RNA treatment, and explore the possibility of the tankyrase-1 as a target of gene therapy for tongue cancer.

METHODSThe replication deficient retrovirus expressing tankyrase-1 antisense RNA was constructed to infect the TCCA-8113 cells. Tankyrase-1 expression was examined by RT-PCR. Telomerase activity was assayed by telomerase repeat amplification protocol (TRAP). Cell proliferation was investigated by cellular growth curve. Cellular apoptosis was detected by flow cytometry method and invert microscope.

RESULTSTankyrase-1 expression and telomerase activity of tongue cancer TCCA-8113 cells were significantly inhibited. There was G(1)-S phase arrest when TCCA-8113 cells were treated with antisense tankyrase-1 transduction. Cellular proliferation was arrested, and cellular apoptosis occurred after antisense tankyrase transduction.

CONCLUSIONSThe transduction of antisense tankyrase-1 by retroviral vector can significantly inhibit the tankyrase-1 expression and telomerase activity of tongue cancer TCCA-8113 cell lines, and arrest the cellular proliferation and promote cellular apoptosis. The tankyrase may be a potential target of gene therapy for tongue cancer.

Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Genetic Therapy ; Genetic Vectors ; genetics ; Humans ; RNA, Antisense ; genetics ; Retroviridae ; genetics ; Tankyrases ; genetics ; Telomerase ; metabolism ; Tongue Neoplasms ; genetics ; metabolism ; pathology ; therapy ; Transfection

In order to study T-bet function in mouse cells, a novel retroviral vector expressing mouse T-bet and reporter gene Thy1.1 was constructed. Retrovirus particles were then produced by transfection of the recombinant retroviral plasmid into a packaging cell line Platinum-E. The recombinant retrovirus played considerable infection ability. T-bet expression was then identified by FACS after infection of CD4+ primary T cells from T-bet knockout mouse with recombinant retrovirus. To determine if exogenous expressing T-bet has normal function, we checked the expression level of T-bet target gene, Ifng. IFN-y expression was upregulated in the T-bet knockout T cells infected with recombinant retrovirus. In conclusion, we successfully constructed an effective mouse T-bet recombinant retroviral vector.
Animals ; Cell Line ; Genetic Vectors ; Interferon-gamma ; metabolism ; Mice ; Mice, Knockout ; Recombinant Proteins ; biosynthesis ; Retroviridae ; T-Box Domain Proteins ; biosynthesis ; T-Lymphocytes ; metabolism ; Transfection