Retroviral vectors encoding ADA regulatory locus control region provide enhanced T-cell-specific transgene expression

Design of non-viral vector with improved regulatory features towards therapeutic application

Viral vectors based gene therapy is often compromised by adverse immunological reactions raising safety concerns. Hence, improved design and development of non-viral vectors with strong regulatory regions is desired. We describe the design of a non-viral mammalian expression vector in which the primary transgene (a truncated dystrophin gene linked with Duchenne muscular dystrophy (DMD)) named microdystrophin delR4-R23/delCT (MD1) is under the transcriptional control of elements of desmin locus control region (DES-LCR). The designed vector, named as DES-LCR/MD1-EGFP, was constructed by cloning two fragments into the pBluescript backbone. Fragment 1 contains DES-LCR enhancer and DES-LCR promoter region while fragment 2 contains MD1 transgene and reporter EGFP (enhanced green fluorescent protein) gene separated by linker P2A (2A peptide). This vector design provides a framework for strong regulation with non-viral features. This design forms the foundation for application in conditions linked to multisystem diseases.

A Systematic Bioinformatics Approach to Motif-Based Analysis of Human Locus Control Regions

Locus control regions (LCRs), cis-acting, noncoding regulatory elements with strong transcription-enhancing activity, are conserved in sequence and organization, and exhibit strict gene-specific expression. LCRs have been reported and studied in several mammalian gene systems, signifying that they play an important role in eukaryotic gene expression control. Their highly regulated, stable, and precise levels of expression have made them a strong candidate for use in gene therapy vectors. In this study, we attempted to determine the unique signatures of human LCRs by analyzing a data set of LCR sequences for the presence of motifs through systematic bioinformatics approach. Using web-based regulatory sequence analysis tools (RSAT), motif-based analysis was performed. Detected significant motifs were analyzed further for their identity using Tomtom tool. RSAT analysis revealed that significant motifs are existent within the LCRs. Identity analysis using Tomtom showed that detected significant motifs were comparable with known transcription factor (TF) binding sites and the top scoring motifs belong to zinc finger-containing proteins, an important group of proteins involved in a variety of cellular activities. Correspondence to segment of known motif indicates the biological relevance of the detected motifs. Motif-based analysis is valuable for analyzing the various characteristics of sequences, notably TF binding models in this study. Owning to their unique expression control abilities, LCRs form an important component of integrating vectors, therefore identification of unique signatures present within LCR sequences will be instrumental in the design of new generation of regulatory elements containing LCR sequences.

Tissue-type plasminogen activator gene targets thrombolysis in atriums

Our previous investigations showed that retroviral gene transfer of tissue-type plasminogen activator (tPA) effectively targeted thrombolysis in vitro and in the model of inferior caval veins of rabbits. This study is to identify the target thrombolysis of retroviral vector recombinant pLEGFP-N1-tPA transferred into the tissue around the Dacron patch (the same materials making of the ring of mechanical valve) in left atriums of rabbits. 70 Dacron patches were transplanted into the left atriums of 70 New Zealand white rabbits. The rabbits were randomly divided into three groups according to the different handling methods, including local pLEGFP-N1-tPA transferred group (gene therapy group, 30 animals), pLEGFP-N1 transferred group (control group, 20 animals), medium DMEM + 10% neonate calf serum (NCS) injected group (blank control group, 20 animals). Samples of blood, Dacron pieces and left atriums (auricles) wall from half of above in each group were harvested on second day and another half were harvested on 75th day after surgery. The EGFP expression of harvested left atriums (auricles) wall were observed under the confocal. The thrombi on the surface of Dacron patches were detected by stereoscope and electron microscope. The tPA expression in left atriums (auricles) wall and in blood from left atriums were detected by Western blot and their thrombolysis and activities were observed and calculated in plasma plates. ELISA were used to identify the contents of tPA. No thrombus was seen on the surface of Dacron patches that were transplanted in left atriums by tPA locally transferring around them. Activity and content of tPA were high in local tissue of left atrium and in blood of left atrium. It demonstrated effectively thrombolysis by tPA rapidly, efficiently and long expressing. This puts the foundation of mechanical valve replacement model for tPA gene valve, next.

Mass spectrometry of murine leukemia virus core proteins

A mass spectrometry (MS) approach was used to analyze viral core proteins of the murine leukemia virus (MuLV)-based gene delivery vector. The retroviral particles produced by traditional methods were concentrated and purified by ultracentrifugation and spin column for matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) MS. MALDI application detected all core MuLV proteins, partial degradation of p10, phosphorylation of p12, as well as the previously unknown formation of a polymeric supramolecular complex between p15 and p30 core proteins. ESI provided information on the post-translational modifications of MuLV core proteins. Data suggest myristoylation of p15 and oxidation of methionine residues in both p12 and p30, whereas cysteine residues in p10, p15 and p30 were not oxidized. The current study demonstrates that MALDI and ESI are efficient tools for viral core protein analysis and can be used as analytical tools in virology and biotechnology of gene delivery vectors.