Safe and efficient delivery of nucleic acids to tissues and cells is a shared challenge in the clinical translation of gene therapy and gene editing. At the intracellular level, DNA delivery is hindered by endo/lysosomal sequestration, inefficient transport into the nucleus and a retention mechanism mediated by the barrier-to-autointegration factor (BAF) protein that detects, clusters and locks away intruding double-stranded DNA in membrane cages. The first two of these intracellular obstacles are well-known bottlenecks and are being addressed by many laboratories. However, preliminary in vitro data suggest the detrimental impact of BAF’s mechanism on transgene expression is underestimated. We hypothesize that transiently suppressing BAF or one of its regulating factors will increase the cytosolic availability and mobility of transfected DNA, facilitating its transport to the nucleus and ultimately boosting transfection efficiency. We will tackle this rather uninvestigated mechanism through two parallel strategies: i) identifying novel small-molecule inhibitors of BAF or its regulators via high-throughput screening of chemical libraries, and ii) producing a recombinant kinase that phosphorylates BAF in situ and thus supresses its DNA-clustering function. The BAF suppressors will be co-delivered to cells with rationally-designed nucleoprotein nanoparticles consisting of a reporter plasmid and a dual-function fusion protein to facilitate endocytosis and endosomal escape. The combined transfection-enhancing effect of the BAF suppressors and the nanoparticles will be extensively characterized in vitro, and in vivo proof-of-concept will be obtained in mice. Besides expanding our fundamental knowledge on this unexplored DNA retention mechanism, the project will provide powerful transfection enhancers that can boost already-existing gene delivery platforms (viral and non-viral), so that these can reach their full potential for gene therapy and gene-editing applications.
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