Screening of potential pseudo att sites of Streptomyces phage ΦC31 integrase in the human genome.

Aim: ΦC31 integrase mediates site-specific recombination between two short sequences, attP and attB, in phage and bacterial genomes, which is a promising tool in gene regulation-based therapy since the zinc finger structure is probably the DNA recognizing domain that can further be engineered. The aim of this study was to screen potential pseudo att sites of ΦC31 integrase in the human genome, and evaluate the risks of its application in human gene therapy.

Methods: TFBS (transcription factor binding sites) were found on the basis of reported pseudo att sites using multiple motif-finding tools, including AlignACE, BioProspector, Consensus, MEME, and Weeder.

Association between the CCR2-Val64Ile polymorphism and susceptibility to HIV-1 infection: a meta-analysis.

Several studies have investigated whether the CCR2-Val64Ile polymorphism affects susceptibility to human immune deficiency virus type-1 (HIV-1), with inconclusive results. Here, we performed a meta-analysis of the literature aiming to clarify the relationship between the polymorphism of CCR2-Val64Ile and the risk of HIV-1 infection. Twelve studies with a total of 6,599 patients, including infants, were selected for inclusion in the analysis.

CCL3L1 copy number variation and susceptibility to HIV-1 infection: a meta-analysis.

Background: Although several studies have investigated whether CCL3L1 copy number variation (CNV) influences the risk of HIV-1 infection, there are still no clear conclusions. Therefore, we performed a meta-analysis using two models to generate a more robust estimate of the association between CCL3L1 CNV and susceptibility to HIV-1 infection.

Methods: We divided the cases and controls into two parts as individuals with CCL3L1 gene copy number (GCN) above the population specific median copy number (PMN) and individuals with CCL3L1 GCN below PMN, respectively.

Histone deacetylase inhibitor Scriptaid reactivates latent HIV-1 promoter by inducing histone modification in in vitro latency cell lines.

Human immunodeficiency virus type 1 (HIV-1) latency remains a major problem for the eradication of viruses in infected individuals undergoing highly active anti-retroviral therapy. By inhibiting HIV-1 gene expression and virus production, histone deacetylase (HDAC) may contribute to the quiescence of HIV-1 within resting CD4+ T cells. A novel HDAC inhibitor, Scriptaid, has been found to have robust activity and lower toxicity compared to trichostatin A (TSA).

TAT-phiC31 integrase mediates DNA recombination in mammalian cells.

Streptomyces phage integrase phiC31 is capable of mediating site-specific insertions in mammalian genomes. To avoid potential toxicity of long-term expression of phiC31 in host cells, we developed a method employing a cell-permeable TAT-phiC31 integrase. His6-tagged phiC31 proteins with or without an HIV TAT intercellular transducing peptide were generated and purified.

Eliminating bacteria backbone of naked DNA enhanced hFIX expression and reduced inflammatory response in mice.

To test the hypothesis that the persistent high level of transgene expression of linear DNA eliminating bacterial backbone (LDEBB) results from less cytokine induction in vivo. We systematically investigated the effect of circular DNA (C DNA), linear DNA (L DNA) and LDEBB on gene expression in mice by hydrodynamics-based plasmid administration, and then determined serum cytokine levels in mice by enzyme linked immunosorbent assay (ELISA). The expression of human clotting factor IX (hFIX) gene in mice treated with LDEBB, L DNA or C DNA reached a maximum 1-day after injection (9809, 6447, 2368 ng/mL), respectively.

DAXX interacts with phage PhiC31 integrase and inhibits recombination.

Phage PhiC31 integrase has potential as a means of inserting therapeutic genes into specific sites in the human genome. However, the possible interactions between PhiC31 integrase and cellular proteins have never been investigated. Using pLexA-PhiC31 integrase as bait, we screened a pB42AD-human fetal brain cDNA library for potential interacting cellular proteins.

Conditional gene modification in mouse liver using hydrodynamic delivery of plasmid DNA encoding Cre recombinase.

The success of Cre-mediated conditional gene targeting in liver of mice has until now depended on the generation of Cre recombinase transgenic mice or on viral-mediated transduction. Here, we sought to establish the feasibility of using hydrodynamic gene delivery of Cre recombinase into liver, using a ROSA26 EGFP mouse. The expression of EGFP and beta-galactosidase was exclusively detected in the liver of mice treated with hydrodynamic gene delivery of Cre recombinase, as assessed with fluorescence microscopy and X-Gal staining, respectively; Southern blotting also showed that Cre mediated recombination occurred specifically in the liver and not in other organs.

A 16bp Rep binding element is sufficient for mediating Rep-dependent integration into AAVS1.

Adeno-associated virus (AAV) is a non-pathogenic virus and the only known eukaryotic virus capable of targeting human chromosome 19 for integration at a well-characterized AAVS1 site. Its site-specific integration is mediated by Rep68 and Rep78, viral proteins that bind to both the viral genome and AAVS1 site on ch19 through a specific Rep-binding element (RBE) located in both the viral genome and AAVS1. There are three RBEs in the AAV genome: two identical ones in both inverted terminal repeats (ITR) and another one in a recently discovered region termed the P5 integration efficiency element (P5IEE) that encompasses the viral P5 promoter.

Efficient delivery of human clotting factor IX after injection of lentiviral vectors in utero.

Aim: To explore gene transfer feasibility for human clotting factor IX (hFIX) mediated by recombinant lentivirus in utero.

Methods: ICR mice fetus at 17-19 d gestation were received lentiviral vectors carrying hFIX cDNA under the control of liver specific promoter by intrahepatic injection. The expression and distribution of hFIX cDNA and possible immune responses against the hFIX were assessed by ELISA, PCR, RT-PCR, and immunohistochemistry, respectively.

Enhancement of naked FIX minigene expression by chloroquine in mice.

Aim: To study the effect of chloroquine on the expression of human clotting factor IX (hFIX) in mice.

Methods: Hydrodynamics-based naked DNA plasmid administration was performed by tail vein injection of 10 microg of pCMV- hFIX and chloroquine (0, 100, 200, and 500 micromol/L) in 2.2 mL of Ringer's solution within 6-7 s, the level and stability of hFIX expression, liver damage and toxicity were then examined.

Generation and characterization of transgenic mice expressing tamoxifen-inducible cre-fusion protein specifically in mouse liver.

Aim: To establish transgenic mice expressing tamoxifen-inducible Cre-ERt recombinase specifically in the liver and to provide an efficient animal model for studying gene function in the liver and creating various mouse models mimicking human diseases.

Methods: Alb-Cre-ERt transgenic mice were produced by microinjecting the construct with Cre-ERt fusion gene of DNA fragments into fertilized eggs derived from inbred C57BL/6 strain. Transgenic mice were identified by using PCR and Southern blotting.

Conditional gene activation in cultured hepatocytes using a ligand-dependent chimeric Cre recombinase.

By combining liver-specific promoter and a chimeric Cre recombinase, conditional gene activation could be finely achieved in hepatocytes at selected time points. To this end, the expression vector of Cre-ERt under the control of the mouse albumin gene promoter/enhancer, alb-Cre-ERt, was constructed, and transfected into engineering BRL (Rat hepatocytes) and BRK (Rat kidney) reporter cells which carries a chromosomally integrated 'floxed' beta geo gene, which is inserted between the promoter and the human alkaline phosphatase( hAP) reporter gene, thereby preventing hAP reporter gene transcription, respectively. After treatment with 1 micromol/L 4-hydroxytamoxifen(4-OHT), a proportion of hAP staining positive cells were detected by hAP staining.

Preliminary study on the production of transgenic mice harboring hepatitis B virus X gene.

AIM:To establish transgenic mice lineage harboring hepatitis B virus X gene and to provide an efficient animal model for studying the exact role of the HBx gene in the process of hepatocarcinogenesis.METHODS:The HBx transgenic mice were produced by microinjecting the construct with X gene of HBV (subtype adr) DNA fragment into fertilzed eggs derived from inbred C57BL/6 strain; transgenic mice were identified by using Nested PCR; expression and phenotype of HBx gene were analyzed in liver from transgenic mic at the age of 8 weeks by RT-PCR, pathologic examination and periodic acid-schiff staining (PAS), respectively.RESULTS:Five hundred and fourteen fertilized eggs of C57 BL/6 mice were microinjected with recombinant retroviral DNA fragment, and 368 survival eggs injected were transferred to the oviducts of 18 pseudopregnant recipient mice, 8 of them became pregnant and gave birth to 20 F1 offspring.

Expression of glutathione S-transferase placental mRNA in hepatic preneoplastic lesions in rats.

AIM:To detect glutathione S-transferase placental (GST-P) mRNA expression in hepatic preneoplastic lesions in rats.METHODS: Using Solit-Farber model, the GST-P mRNA expression was observed in hepatic preneoplastic lesions induced by diethylnitrosamine (DEN) in rats and normal and regenerated hepatic tissues in the control group by in situ hybridization.RESULTS: GST-P mRNA was mainly expressed in altered hepatic foci (AHF) and some of the oval cells in hepatic preneoplastic lesions and the extent of its expression was different among various foci or/and positive cells in the same focus whereas no expression was observed in normal and regenerated hepatic tissues.