Project description:The advancement in translational research, such as gene therapy, stem cell engineering and molecular medicine, can be realized on the pretext of genetic engineering at cellular level. However, the challenge of inserting large transgene cassettes into the human genome could be an impediment to this advancement, which makes the cell engineering process a critical parameter. Current practices, including random integration transgenesis tools (viral and transposon-based) or specific genome manipulation tools (endonuclease-based) are suboptimal in delivering large transgenes and also pose safety concerns. To address this void, we had developed and reported a novel transgenesis tool derived from phage λ integrase that precisely recombines large plasmid DNA into an endogenous sequence found in about 1000 human Long INterspersed Elements-1 (LINE-1) in various human cell lines. As an improved extension to mitigate the biosafety concerns to the minimal and enhance the uptake and efficiency of transgene expression, we report here a technologically advanced λ-Int platform, wherein we show efficient derivation of seamless negatively supercoiled transgene vectors from the conventional plasmid DNA using in vitro intermolecular recombination followed by its integration into human LINE-1 elements via prototypical λ-Int system. Additionally, we have identified specific LINE-1 as preferred seamless vector insertion sites for λ-Int mediated transgenesis. Characteristically, this new platform achieves sustainable, high-level transgene expression as exemplified by a CD19 chimeric antigen receptor expression from targeted LINE-1 in hESCs cells. Therefore, we demonstrate that our novel seamless vector platform has the potential to be broadly applied across different applications in biotechnology and molecular medicine.
Project description:Different attB or attP DNA libraries containing 7-bp random nucleotides were used for in vitro recombination mediated by the purified integrase from mv4 bacteriophage against their cognate wild-type attB or attP recombination site.
Project description:The two obstacles that impede a wider application of genetically modified cells expressing therapeutic transgenes for ex vivo gene therapy are the immune mediated rejection of the transplanted cells, combined with their potential to cause iatrogenic oncogenesis. In this study we describe a new cellular vehicle for this form of therapy,; termed the cord lining epithelial cell (CLEC). CLECs are derived from the human amnion and incorporate many of the immunoregulatory functions associated with the fetal/maternal interface. We show that CLECs can be safely transfected by phage ÏC31 integrase to accomplish site-specific integration of a therapeutic human transgene. We also show that transplanted CLECs are not oncogenic in vivo and can be maintained in immunocompetent mice where acute xeno-rejection rapidly destroys other human cell types. Finally, we demonstrate the utility of CLECs for ex vivo gene therapy by delivering human coagulation factor 8 to mice with Hemophilia A. Experiment Overall Design: The transcriptome datasets of human umbilical cord lining epithelial cells were compared before(CLEC) and 1 month after(CLEC-GFP) phage integrase mediated integration of EGFP cDNA into the genome. Transcriptome datasets were generated in singles and genes differentiallty expressed in cells before and after phage integrase treatment were analysed. Genes differentially expressed by at least 2 fold as compared to untreated CLEC were considered to be significantly dysregulated. List of genes with significant dysregulation were used for further analysis and to used to determine if genomic integration events had resulted in any potential geno-toxicity.
Project description:Co-IP of HIV-1 integrase proteins - WT, K258R and K258/264/266/273R. Integrase proteins were cloned into a mammalian expression vector (pJET). All proteins had an N-terminal HA-tag used for IP. As a negative control, cells were transfected with an empty HA vector. Co-IPs were done in HEK293T cells.
Project description:The Gal4/UAS system is used across model organisms to overexpress target genes in precise cell types and relies on generating transgenic Gal4 driver lines. In zebrafish, the Tg(elavl3:KalTA4) (HuC) line drives robust expression in neurons. We observed an increased prevalence of swim bladder defects in Tg(elavl3:KalTA4) zebrafish larvae compared to wildtype siblings, which prompted us to investigate whether transgenic larvae display additional neurobehavioral phenotypes. Tg(elavl3:KalTA4) larvae showed alterations in brain activity, brain morphology, and behavior, including increased hindbrain size and reduced activity of the cerebellum. Bulk RNA-seq analysis revealed massive dysregulation of the transcriptome and suggested an increased ratio of neuronal progenitor cells compared to differentiated neurons. To understand whether these phenotypes derive from Gal4 toxicity or from positional effects related to transgenesis, we used economical low-pass whole genome sequencing to map the Tol2-mediated insertion site to chromosome eight. Reduced expression of the neighboring gene gadd45ga, a known cell cycle regulator, is consistent with increased proliferation and suggests a role for positional effects. Challenges with creating alternative pan-neuronal lines include the length of the elavl3 (HuC) promoter (9 kb) and random insertion using traditional transgenesis methods. To facilitate the generation of alternative lines, we cloned five neuronal promoters (atp6v0cb, elavl3, rtn1a, sncb, and stmn1b) ranging from 1.7 kb to 4.3 kb and created KalTA4 lines using Tol2 and the phiC31 integrase-based pIGLET system. Our study highlights the importance of using appropriate genetic controls and establishes a roadmap for identifying positional effects in new transgenic lines.
Project description:The Gal4/UAS system is used across model organisms to overexpress target genes in precise cell types and relies on generating transgenic Gal4 driver lines. In zebrafish, the Tg(elavl3:KalTA4) (HuC) line drives robust expression in neurons. We observed an increased prevalence of swim bladder defects in Tg(elavl3:KalTA4) zebrafish larvae compared to wildtype siblings, which prompted us to investigate whether transgenic larvae display additional neurobehavioral phenotypes. Tg(elavl3:KalTA4) larvae showed alterations in brain activity, brain morphology, and behavior, including increased hindbrain size and reduced activity of the cerebellum. Bulk RNA-seq analysis revealed massive dysregulation of the transcriptome and suggested an increased ratio of neuronal progenitor cells compared to differentiated neurons. To understand whether these phenotypes derive from Gal4 toxicity or from positional effects related to transgenesis, we used economical low-pass whole genome sequencing to map the Tol2-mediated insertion site to chromosome eight. Reduced expression of the neighboring gene gadd45ga, a known cell cycle regulator, is consistent with increased proliferation and suggests a role for positional effects. Challenges with creating alternative pan-neuronal lines include the length of the elavl3 (HuC) promoter (9 kb) and random insertion using traditional transgenesis methods. To facilitate the generation of alternative lines, we cloned five neuronal promoters (atp6v0cb, elavl3, rtn1a, sncb, and stmn1b) ranging from 1.7 kb to 4.3 kb and created KalTA4 lines using Tol2 and the phiC31 integrase-based pIGLET system. Our study highlights the importance of using appropriate genetic controls and establishes a roadmap for identifying positional effects in new transgenic lines.
Project description:We established a two-step approach to centromere-replacement (Figure 1A in outline, and Supplementary data in detail). FiC31 integrase was used to place a candidate sequence or an empty vector adjacent to the native centromere of chromosome 2 of CBS2777, and Bxb1 integrase was subsequently used to delete the native centromere.
Project description:The two obstacles that impede a wider application of genetically modified cells expressing therapeutic transgenes for ex vivo gene therapy are the immune mediated rejection of the transplanted cells, combined with their potential to cause iatrogenic oncogenesis. In this study we describe a new cellular vehicle for this form of therapy, termed the cord lining epithelial cell (CLEC). CLECs are derived from the human amnion and incorporate many of the immunoregulatory functions associated with the fetal/maternal interface. We show that CLECs can be safely transfected by phage φC31 integrase to accomplish site-specific integration of a therapeutic human transgene. We also show that transplanted CLECs are not oncogenic in vivo and can be maintained in immunocompetent mice where acute xeno-rejection rapidly destroys other human cell types. Finally, we demonstrate the utility of CLECs for ex vivo gene therapy by delivering human coagulation factor 8 to mice with Hemophilia A. High-resolution copy number profiling was performed on genomic DNA of untreated (GSM315546 and GSM315713) and phage integrase modified CLECs (GSM315974 and GSM316895) using the Human Mapping 500K Array Set (Affymetrix) and the data analyzed using GeneChip Chromosome Copy Number Analysis Tool. Regions of copy number gain or loss were defined as having 3 consecutive SNPs concordant for significant copy number abnormalities. Log2 signal intensity ratios >0.3 and <-0.3 were criteria for significant copy number gain and loss, respectively.
Project description:Investigation of whole genome gene expression level changes in HT1080 fibrosarcoma cell line after transfection CRABP1 gene and R131A CRABP1 mutant (arginine-alanine substitution in a protein active site, protein lacks the ability to interact with retinoic acid), compared to HT1080 line transfected with empty pLXSN vector.
Project description:Induced pluripotent stem cells (iPSCs) can be derived from somatic cells by the introduction of the transcription factors Oct4, Sox2, Klf4 and cMyc using various methods. Here, we describe a new approach for the derivation of murine iPSCs using a polycistronic non-viral inducible vector integrated into pseudo attP sites via the C31 integrase-mediated site-specific recombination and subsequent vector excision by Cre recombinase. The pluripotency of the derived iPSCs was proved by in vitro and in vivo tests. The derived transgene-free iPSCs reactivated the endogenous pluripotency genes like e.g. Oct4, Sox2 and Nanog and the global gene expression profiles of iPSCs lines are highly similar to ESCs and distinct from parental murine fibroblasts. We demonstrated the differentiation potential of iPSCs by generation cells of the three germ layers as well as we successfully created germline chimeric mice from transgene-free iPSCs. In this study, we presented an efficient method for the generation of transgene-free iPSCs using dual-recombinase technology. expression data of iPSCs/ESCs/MEFs