MODULATION OF THE SPECIFICITY AND ACTIVITY OF A CELLULAR PROMOTER IN AN ADENOVIRAL VECTOR

Most gene therapy studies with recombinant adenoviruses employ viral p romoters and lack tissue specificity, To determine whether a tissue-sp ecific cellular promoter inserted into the adenoviral genome can direc t the expression of a reporter gene in a tissue-specific manner, recom binant adenoviruses containing a nuclear lacZ gene driven by a human v entricular/slow muscle myosin light chain 1 promoter with and without a muscle creatine kinase enhancer were constructed, The ability of the se viruses to express the reporter genes in infected myogenic and nonm yogenic cell lines was studied, Intramuscular injection of these virus es into mice showed that little or no reporter gene expression occurre d in muscle fibers, although a relatively high level of lacZ gene expr ession was observed in surrounding connective tissue. Insertion of ade novirus sequences from the 5' inverted terminal repeat (ITR) region an d/or the protein IX region into plasmids resulted in decreased reporte r gene expression from myosin light chain 1 promoter in transfected C2 C12 myotubes and 293 cells, as well as in injected muscles, These resu lts suggested that negative elements are present in the adenoviral gen ome, This negative effect seems neither tissue nor species specific Ad enovirus cis-elements that may affect the specificity and activity of a cellular promoter are discussed.