The goal of this project is to demonstrate the efficacy of Sleeping Beauty (SB) transposons as vectors for non-viral gene delivery to treat mucopolysaccharidosis (MPS) diseases, specifically Type I, a-iduronidase (IDUA). The project has two sub-goals: 1) Complete experiments that reveal the efficacy of delivery of SB transposons to the mouse to treat a//of the effects of IDUA-deficiency; in particular restoration of IDUA activity in the brain (Aim 1). 2) Reduce potential cytotoxic effects of SB transposon integrants by directing transposition to safe harbors in the mouse genome (Aims 2 - 4). Aim 1 will complete our assessment of the SB system as a vector for gene delivery in the mouse. The next step for development of the SB system for humans is to maximize the safety of using transposons that randomly integrate into genomes by directing their integration to sites that are thought to be safe. The principal hvpotheses of this proposal are: 1) Transposons can be delivered directly into the liver and brain for uptake and expression of the gene(s) they carry. 2) Certain features of SB Transposons can be exploited to direct their integration into specific sequences in genomes that are considered safe and thereby avoid some of the issues associated with viruses used as gene delivery vectors. The Specific Aims of the proposal are to 1) determine the efficacy of SB transposon delivery to the brain in MPS I mice, 2) develop a 'universal' targeting system to direct SB transposons into selected regions of a DNA molecule, 3) evaluate the ability of a 'universal' targeting system to direct SB transposons to selected regions of the mouse genome in vitro, and 4) evaluate the ability of a 'universal' targeting system to direct SB transposons to selected regions of the genome in the liver of a living mouse. IMPACT: There are two major impacts of our proposed studies. 1) We will demonstrate that SB transposons can be effectively used to achieve long-term expression in the brain as well as in other tissues and cell types without using viral vectors. 2) By targeting integration of SB transposons to specific sites in the mouse genome, the concerns of insertional mutagenesis will be reduced considerably.