Research Gallery > Regulating Gene Expression with                                                Laser-activated Oligonucleotides

The goal of this project is to design light-activated molecules and microscopy methods for quantitatively controlling mRNA translation and siRNA activity in space and time within living cells and organisms.  In this way, it will be possible to turn genes "on" and "off" with light.  This technology will allow the delicate perturbation of genes important in the embryonic development of many model organisms, neuronal function, zebrafish fin regeneration, and will also have possible therapeutic applications involving cell-specific gene inactivation.  

We are synthesizing caged DNA and RNA with transient blocking groups that can be cleaved by 350-365 nm light.  We have developed several new synthetic strategies that allow the site-specific incorporation of a single photoactive blocking group on the oligonucleotide.  Our compounds are designed so that laser activation leads to a greatly enhanced fluorescent signal.  By quantifying this fluorescence, as we demonstrated recently in living sea urchin and zebrafish embryos, it will be possible to control the concentration, and form molecular gradients of important signaling molecules.  As a proof-of-concept, photoactivatable DNA oligonucleotides have been synthesized that target chordin, a protein important in dorsal-ventral axis patterning in zebrafish, and many other organisms.  Chordin, and its partner, bone morphogenetic protein 4 (BMP-4), are of widespread biomedical interest.  These studies are being conducted in collaboration with UPenn zebrafish biologist, Prof. Eric Weinberg.  Ongoing studies in the lab also involve synthesizing caged mRNAs, in collaboration with UPenn Prof. Jim Eberwine.  After developing these technologies, we will share them with other researchers to target different genes and organisms.   The lab has recently purchased a state-of-the-art UV confocal microscope from Olympus (FV1000) that will make it possible to perform precise  in vivo uncaging studies.