title: Regulated expression of a transgene introduced on an oriP/EBNA-1 PAC shuttle vector into human cells.
abstract: BACKGROUND
  Sequencing of the human genome has led to most genes being available in BAC or PAC vectors. However, limited functional information has been assigned to most of these genes. Techniques for the manipulation and transfer of complete functional units on large DNA fragments into human cells are crucial for the analysis of complete genes in their natural genomic context. One limitation of the functional studies using these vectors is the low transfection frequency.
  
  
  RESULTS
  We have constructed a shuttle vector, pPAC7, which contains both the EBNA-1 gene and oriP from the Epstein-Barr virus allowing stable maintenance of PAC clones in the nucleus of human cells. The pPAC7 vector also contains the EGFP reporter gene, which allows direct monitoring of the presence of PAC constructs in transfected cells, and the Bsr-cassette that allows highly efficient and rapid selection in mammalian cells by use of blasticidin. Positive selection for recombinant PAC clones is obtained in pPAC7 because the cloning sites are located within the SacBII gene. We show regulated expression of the CDH3 gene carried as a 132 kb genomic insert cloned into pPAC7, demonstrating that the pPAC7 vector can be used for functional studies of genes in their natural genomic context. Furthermore, the results from the transfection of a range of pPAC7 based constructs into two human cell lines suggest that the transfection efficiencies are not only dependent on construct size.
  
  
  CONCLUSIONS
  The shuttle vector pPAC7 can be used to transfer large genomic constructs into human cells. The genes transferred could potentially contain all long-range regulatory elements, including their endogenous regulatory promoters. Introduction of complete genes in PACs into human cells would potentially allow complementation assays to identify or verify the function of genes affecting cellular phenotypes.
authors.affiliation: Department of Medical Genetics, Ullevål University Hospital and Faculty of Medicine, University of Oslo, Oslo, Norway. hanneas@medisin.uio.no
authors.forename: Hanne A
authors.initials: HA
authors.lastname: Askautrud
authors.forename: Elisabet
authors.initials: E
authors.lastname: Gjernes
authors.forename: Gro L
authors.initials: GL
authors.lastname: Størvold
authors.forename: Mona M
authors.initials: MM
authors.lastname: Lindeberg
authors.forename: Jim
authors.initials: J
authors.lastname: Thorsen
authors.forename: Hans
authors.initials: H
authors.lastname: Prydz
authors.forename: Eirik
authors.initials: E
authors.lastname: Frengen
mesh_terms: D015820:Cadherins / Q000235:genetics; D002460:Cell Line; D022202:Chromosomes, Artificial, Bacterial; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics*; D005786:Gene Expression Regulation; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D014162:Transfection; D019076:Transgenes
chemical_list: C512197:CDH3 protein, human; D015820:Cadherins; D019309:Epstein-Barr Virus Nuclear Antigens; C417029:EBV-encoded nuclear antigen 1