Rationally designed light-inducible RNA-releasing protein for translational regulation and optogenetic control of gene therapies

In this study, we describe a rationally designed light-inducible RNA-releasing protein (LIRP) capable of inhibiting mRNA translation in the dark while permitting gene expression upon exposure to blue or ambient light. This LIRP-dependent gene switch is compatible with various delivery routes of gene- and cell-based therapy, such as subcutaneous implantation of microencapsulated light-sensitive cells or expression in various light-accessible body sites using single adeno-associated virus (AAV) vectors. To exemplify a gene therapy approach that directly harnesses ambient light as a natural illumination source to induce therapeutic action, we show how intradermal delivery of AAV2 vectors carrying a LIRP-regulated gene switch controlling murine thymic stromal lymphopoietin expression was effective in enabling light-dependent prevention and treatment of diet-induced obesity. To describe another therapeutic scenario, we engineered AAV2 vectors for LIRP-dependent expression of Vascular endothelial growth factor (VEGF) inhibitors for the treatment of retinal neovascular diseases. Upon intravitreal delivery into mice suffering from wet macular degeneration, VEGF inhibitors were constantly produced when animals were exposed to daylight, but therapeutic actions could be flexibly interrupted either by exposure to dark environments or by administration of a selective blue light filter at any point in time. When compared to conventional treatment strategies based on constitutive VEGF inhibition over the course of 3 months, we show that a regulated gene therapy approach through LIRP-dependent optogenetics was advantageous in maintaining a normal retina thickness. This work not only provides a valuable addition to the optogenetic toolbox but also offers a perspective to translate light-dependent gene switches toward therapeutic usage.