Molecular light switches for controlling gene function

BIOL 137

XinJing Tang, xinjingt@sas.upenn.edu, Julia L. Richards, and Ivan J. Dmochowski, ivandmo@sas.upenn.edu. Department of Chemistry, University of Pennsylvania, 231 South 34th St., Philadelphia, PA 19104-6323
Our lab is designing photoactive oligonucleotides with the goal of controlling in vivo gene expression with high spatial and temporal control. As proof-of-principle, DNA polymerase activity was modulated 25-fold using UV light. More recently, methods have been developed for controlling DNA and RNA hybridization. For example, hybridization of an antisense oligodeoxynucleotide (asODN) to a target mRNA can inhibit translation by sterically blocking the ribosome and/or recruiting endogenous ribonucleases. A series of light-activated DNA hairpins was synthesized by covalently attaching a 20-mer asODN to a complementary sense strand through a heterobifunctional photocleavable linker. The photoactive conjugates were stabilized by ~ 1-4 kcal/mole compared to the corresponding asODN/sODN duplexes. These differences in stability made it possible to regulate asODN/RNA duplex formation. In vitro RNase H assays showed 3-10-fold increases in RNA degradation upon photoactivation of the asODN/sODN hairpin. Experiments to photoregulate genes within leukemia cells, neurons, and zebrafish embryos will be described.