All Human Efi Alpha Promoters Are Not Equal: Markedly Affect Gene Expression In Constructs From Different Sources

The promoter is a major element in the expression cassette of gene therapy vectors. Optimal promoter selection can enhance target specificity and gene expression. Recently, we evaluated three different human elongation factor 1 alpha (EFI alpha) promoters. The three promoters were put into the same expression vector, pAC-luc, driving expression of the luciferase cDNA. The activity from one EFI alpha promoter (termed EFI alpha-3), obtained in a commercial vector, was markedly lower when tested in vitro (from 50 - 500 x) in four cell lines and in vivo in rat submandibular glands (similar to 250 x). Sequence differences in the EFI alpha -3 promoter likely account for the activity differences seen. Investigators need to recognize that all promoters of the same name may not be equivalent in driving transgene expression.