title: Regulated expression of murine CD40L by a lentiviral vector transcriptionally targeted through its endogenous promoter.
abstract: BACKGROUND
  Targeted lentiviral vectors may contribute to circumventing genotoxicity associated with uncontrolled transcription of therapeutic genes. Some vectors replacing strong viral sequences for gene promoters such as β-globin, CD4, CD19 or Igκ were able to drive tissue-specific expression of the transgene. Gene therapy, however, faces even greater hurdles when the therapeutic transgene is subject to strict regulatory mechanisms. This is the case of the CD40LG gene, which encodes for the CD154 (also known as CD40L) molecule, transiently expressed upon activation on CD4(+) T cells. Mutations in this gene cause the X-linked hyper IgM syndrome (HIGM1) in humans because the interaction of CD40L with its ligand CD40 triggers signals that are critical for the immunobiology of B lymphocytes.
  
  
  METHODS
  We developed a lentiviral vector containing the murine Cd40lg cDNA under the control of its endogenous promoter.
  
  
  RESULTS
  The CD4(+) BW5147 T cells transduced with the pCd40lg-Cd40lg lentiviral vector express CD40L only upon stimulation. The intensity of the expression correlates with the number of vector integrations per cell and detected molecules rapidly decay after removing the stimulating agent. The tissue-specific, activation-dependent and reversible expression of CD40L fully mimics the physiological induction and disappearance of the molecule from the surface of murine T lymphocytes. The functional activity of the regulated lentiviral vector is demonstrated by the ability of transduced BW5147 cells to promote the proliferation of purified B cell splenocytes.
  
  
  CONCLUSIONS
  We have developed a fine-regulated lentiviral vector that can be a model for expressing molecules subject to stringent regulatory mechanisms.
authors.affiliation: Institute of Biopathology and Regenerative Medicine, Center for Biomedical Research, University of Granada. Health Sciences Technology Park, Armilla, Granada, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Fernández-Rubio
authors.affiliation: Institute of Biopathology and Regenerative Medicine, Center for Biomedical Research, University of Granada. Health Sciences Technology Park, Armilla, Granada, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Torres-Rusillo
authors.affiliation: Institute of Biopathology and Regenerative Medicine, Center for Biomedical Research, University of Granada. Health Sciences Technology Park, Armilla, Granada, Spain.
authors.forename: Ignacio J
authors.initials: IJ
authors.lastname: Molina
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D023201:CD40 Ligand / Q000276:immunology* / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D018390:Gene Targeting; D005822:Genetic Vectors; D016086:Lentivirus; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D011401:Promoter Regions, Genetic; D014161:Transduction, Genetic
chemical_list: D023201:CD40 Ligand
keywords: CD154; CD40L; HIGM1; Hyper IgM syndrome; lentiviral vectors; regulated transgene expression; transcriptional targeting