Retinal degenerative diseases affect 9 million Americans. Among these conditions, retinitis pigmentosa (RP) is among the most devastating. Mutations in genes encoding subunits of the rod-specific enzyme, cyclic guanosine monophosphate (cGMP) phosphodiesterase 6 (PDE6A and PDE6B), are responsible for approximately 72,000 cases of RP worldwide each year, making therapeutic modeling highly relevant to developing mechanisms based therapies. In both RP and age-related macular degeneration (AMD), progressive atrophy of rod photoreceptors leads to secondary death of cone photoreceptors. Gene therapy could enhance rod viability and prevent secondary cone loss. These FDA trials used wild-type (wt) gene supplementation (i.e., overexpression of a normal version of the gene) in diseased cells to overcome the abnormality of the patients' mutated genes. The first human gene therapy trial for early onset retinal degeneration found visual function recovered initially, but did not retard the rate of photoreceptor degeneration, and the gene therapy treated RP patients now continue their march toward blindness. The failure of FDA trials to attenuate the progression of rod death suggests that there is a point of no return for rod viability in retinal disease and presents a major obstacle to the treatment of RP. We hypothesize that this retinal point of no return derives from 1) changes in Ca2+ homeostasis and 2) inadequate activation of the mammalian target of rapamycin (mTOR) self-survival pathway. Preliminary data suggest that the point of no return could be halted by administering two therapeutic constructs via bipartite vectors in an autosomal recessive PDE6-RP model (arRP) (Aims 1 and 2). In photoreceptors, incoming light activates PDE6, which hydrolyzes free cGMP. Lower free cGMP levels close cGMP-gated Na+/Ca2+ cation (CNG) channels in the plasma membrane, reducing cation influx and propagating nerve impulses.
Aims 1 and 2 test therapeutic strategies aimed at remedying PDE6 deficiency. Specifically, shRNA knockdown will be used to identify therapeutic targets using two novel bipartite AAV8 vectors described in detail herein. Finally, wt gene supplementation leaves the patient's mutant genes intact, which could continuously trigger ongoing damage despite the presence of a wt gene in a diseased cell. A gene editing approach could overcome this defect. Thus, Aim 3 explores in vivo AAV mediated CRISPR-gene editing in PDE6-RP models available on campus: 3a) the Pde6a mutant mouse; and 3b) human stem cells from an RP patient bearing the PDE6A mutations (OMIM# 180071), which offers an in vitro model for comparing CRISPR efficacy in human cells vs. Pde6a mouse retina.
The proposed research is relevant to public health because the goal is to develop gene therapy approaches that explore in vivo gene editing and correction tools for the eye to treat both autosomal recessive and dominant forms of retinitis pigmentosa, which are inherited eye disorders that ultimately cause blindness. Thus, the proposed research is relevant to the part of the NEI's 'Audacious Goals' pertaining to research with respect to blinding eye diseases and preservation of sight.
| Koch, Susanne F; Tsang, Stephen H (2018) Success of Gene Therapy in Late-Stage Treatment. Adv Exp Med Biol 1074:101-107 |
| Wert, Katherine J; Velez, Gabriel; Cross, Madeline R et al. (2018) Extracellular superoxide dismutase (SOD3) regulates oxidative stress at the vitreoretinal interface. Free Radic Biol Med 124:408-419 |
| Evans, Lucy P; Newell, Elizabeth A; Mahajan, MaryAnn et al. (2018) Acute vitreoretinal trauma and inflammation after traumatic brain injury in mice. Ann Clin Transl Neurol 5:240-251 |
| Sengillo, Jesse D; Lee, Winston; Bakhoum, Mathieu F et al. (2018) CHOROIDEREMIA ASSOCIATED WITH A NOVEL SYNONYMOUS MUTATION IN GENE ENCODING REP-1. Retin Cases Brief Rep 12 Suppl 1:S67-S71 |
| Xu, Christine L; Park, Karen Sophia; Tsang, Stephen H (2018) CRISPR/Cas9 genome surgery for retinal diseases. Drug Discov Today Technol 28:23-32 |
| Kroeger, Heike; Grimsey, Neil; Paxman, Ryan et al. (2018) The unfolded protein response regulator ATF6 promotes mesodermal differentiation. Sci Signal 11: |
| Jauregui, Ruben; Park, Karen Sophia; Duong, Jimmy K et al. (2018) Quantitative Comparison of Near-infrared Versus Short-wave Autofluorescence Imaging in Monitoring Progression of Retinitis Pigmentosa. Am J Ophthalmol 194:120-125 |
| Machlab, Daniel A; Velez, Gabriel; Bassuk, Alexander G et al. (2018) ProSave: an application for restoring quantitative data to manipulated subsets of protein lists. Source Code Biol Med 13:3 |
| Apatoff, Mary Ben L; Sengillo, Jesse D; White, Eugenia C et al. (2018) Autologous stem cell therapy for inherited and acquired retinal disease. Regen Med 13:89-96 |
| Tsang, Stephen; Bakhoum, Mathieu; Sengillo, Jesse (2018) Mitochondrial A3243G mutation results in corneal endothelial polymegathism. Graefes Arch Clin Exp Ophthalmol 256:1213 |
Showing the most recent 10 out of 61 publications
