title: Regulatory elements of the vav gene drive transgene expression in hematopoietic stem cells from adult mice.
abstract: OBJECTIVE
  Previous studies have shown that the HS21/45 promoter of the vav protooncogene drives a predominant expression of exogenous transgenes in mouse hematopoietic cells, including clonogenic bone marrow (BM) progenitors. We investigated the activity of this promoter in the hematopoietic stem cell compartment of adult mice.
  
  
  METHODS
  Inbred Ly5.1 transgenic mice expressing a nonfunctional human CD4 marker gene (hCD4) under the control of the HS21/45 promoter were generated. BM cells from these animals were sorted based on the intensity of hCD4 expression. Fractions characterized by high, intermediate, or low/negative expression of the transgene were then assessed for their competitive repopulation ability (CRA), using unfractionated BM cells from Ly5.2 mice as a reference competitor population.
  
  
  RESULTS
  Data showed that BM cells having a low/negative or intermediate expression of hCD4 had a very poor hematopoietic CRA. In contrast, BM cells with high hCD4 expression were characterized by a high CRA. These observations were confirmed in the short- and long-term posttransplantation of primary and secondary recipients when analyzing the lymphoid and myeloid cells of recipient mice.
  
  
  CONCLUSIONS
  Our results demonstrate for the first time that the regulatory HS21/45 sequence of the vav gene constitutes an efficient promoter for driving transgene expression in multipotent hematopoietic stem cells residing in the BM of adult mice. Thus, this promoter is proposed for the development of transgenic mice and gene therapy vectors that require restricted expression of exogenous transgenes in cells of the hematopoietic system, including primitive hematopoietic stem cells.
authors.affiliation: Gene Therapy Programme, Centro de Investigaciones, Energéticas, Medioambientales y Tecnológicas/Marcelino Botín Foundation, Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Almarza
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Segovia
authors.forename: Guillermo
authors.initials: G
authors.lastname: Guenechea
authors.forename: Susana G
authors.initials: SG
authors.lastname: Gómez
authors.forename: Angel
authors.initials: A
authors.lastname: Ramírez
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Bueren
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D015704:CD4 Antigens / Q000096:biosynthesis / Q000235:genetics; D018797:Cell Cycle Proteins; D002999:Clone Cells / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D039902:Multipotent Stem Cells / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051567:Proto-Oncogene Proteins c-vav; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000235:genetics; D019076:Transgenes / Q000235:genetics*
chemical_list: D015704:CD4 Antigens; D018797:Cell Cycle Proteins; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011993:Recombinant Fusion Proteins; C496618:VAV1 protein, human; C496619:Vav1 protein, mouse