Photocaged Morpholino Oligomers for the Light-Regulation of Gene Function in Zebrafish and Xenopus Embryos

Morpholino oligonucleotides, or morpholinos, have emerged as powerful antisense reagents for evaluating gene function in both in vitro and in vivo contexts. However, the constitutive activity of these reagents limits their utility for applications that require spatiotemporal control, such as tissue-specific gene disruptions in embryos. Here we report a novel and efficient synthetic route for incorporating photocaged monomeric building blocks directly into morpholino oligomers and demonstrate the utility of these caged morpholinos in the light-activated control of gene function in both cell culture and living embryos. We demonstrate that a caged morpholino that targets enhanced green fluorescent protein (EGFP) disrupts EGFP production only after exposure to UV light in both transfected cells and living zebrafish (Danio rerio) and Xenopus frog embryos. Finally, we show that a caged morpholino targeting chordin, a zebrafish gene that yields a distinct phenotype when functionally disrupted by conventional morpholinos, elicits a chordin phenotype in a UV-dependent manner. Our results suggest that photocaged morpholinos are readily synthesized and highly efficacious tools for light-activated spatiotemporal control of gene expression in multiple contexts.