NUCLEAR-LOCALIZATION SIGNALS - A DRIVING-FORCE FOR NUCLEAR TRANSPORT OF PLASMID DNA IN ZEBRAFISH

Nuclear localization signals (NLSs) are short peptides required for nu clear transport of karyophilic proteins. We review in this paper how t he nuclear targeting property of NLS peptides has been taken advantage of to enhance the efficiency of nuclear uptake of transgene DNA in ze brafish and-how it may improve the efficiency of transgenesis in this species. Synthetic NLS peptides can bind to plasmid DNA by ionic inter actions. Cytoplasmic injection of DNA-NLS complexes in zebrafish eggs enhances the rate and the amount of plasmid DNA taken up be embryonic nuclei. Nuclear import of DNA-NLS complexes has been duplicated in vit ro and exhibits energetic and cytosolic requirements similar to those for nuclear protein import. Furthermore, binding NLSs to DNA increases expression frequency of the transgene. We suggest that NLS peptides m ay constitute a valuable tool to improve the efficiency of transgenesi s in zebrafish and other species.