Nuclear entry of nonviral vectors

Abstract

Nonviral gene delivery is limited to a large extent by multiple extracellular and intracellular barriers. One of the major barriers, especially in nondividing cells, is the nuclear envelope. Once in the cytoplasm, plasmids must make their way into the nucleus in order to be expressed. Numerous studies have demonstrated that transfections work best in dividing populations of cells in which the nuclear envelope disassembles during mitosis, thus largely eliminating the barrier. However, since many of the cells that are targets for gene therapy do not actively undergo cell division during the gene transfer process, the mechanisms of nuclear transport of plasmids in nondividing cells are of critical importance. In this review, we summarize recent studies designed to elucidate the mechanisms of plasmid nuclear import in nondividing cells and discuss approaches to either exploit or circumvent these processes to increase the efficiency of gene transfer and therapy. Gene Therapy (2005) 12, 881-890.

Cell-specific nuclear import of plasmid DNA in smooth muscle requires tissue-specific transcription factors and DNA sequences

“…We, and others, have subsequently shown that nuclear import of plasmid DNA is sequence dependent, requires karyopherins (importins) and the small GTPase RAN, and occurs through the nuclear pore complex (NPC). [14][15][16][17][18] In our model of plasmid nuclear import, we propose that transcription factors present in the cytoplasm bind to the DTS and coat the plasmid with nuclear localization sequences (NLSs) that utilize importins to cross the NPC, which regulates the nucleocytoplasmic shuttling of macromolecules during interphase. [19][20][21] We have also developed a tissue-specific DTS, utilizing the smooth muscle g-actin (SMGA) promoter, that mediates nuclear import of pDNA specifically in smooth muscle cells (SMCs).…”

Matrices and scaffolds for DNA delivery in tissue engineering

“…For non-viral vectors in particular, intracellular trafficking of a plasmid is a limiting factor, which is illustrated by the observation that intracellular levels of plasmid were 2 to 3 orders of magnitude greater than the number of adenoviral particles [34]. Vectors are thus being designed with endosomal escape moieties [35,36], or degradable components to facilitate dissociation of the plasmid from the vector [37][38][39][40], or nuclear localization signals [41]. As these vectors are applied to tissue engineering and scaffold-based delivery, an additional design parameter that must be considered is the interaction between the vector and the material.…”

Intracellular partitioning of cell organelles and extraneous nanoparticles during mitosis

“…Nucleic acids should also remain intact as their sequence ensures their biological activity. In recent years the notion that for maximal transfection the pDNA not just needs to reach the nucleus, but rather gain access to the right intranuclear compartment has been gaining increasing recognition [1][2][3]. Moreover, transfection efficiency can differ substantially between cell types, and within one cell type, between various phases of the cell cycle [4,5].…”