Taking control of gene expression with light-activated oligonucleotides

The recent development of caged oligonucleotides that are, efficiently activated by ultraviolet (UV) light creates opportunities for regulating gene expression with very high spatial and temporal resolution. By selectively modulating gene activity, these photochemical tools will facilitate efforts to elucidate gene function and may eventually serve therapeutic aims. We demonstrate how the incorporation of a photocleavable blocking group within a DNA duplex can transiently arrest DNA polymerase activity. Indeed, caged oligonucleotides make it possible to control many different protein-oligonucleotide interactions. In related experiments hybridization of a reverse complimentary (antisense) oligodeoxynucleotide to target mRNA can inhibit translation by recruiting enclogenous RNases or sterically blocking the ribosome. Our laboratory recently synthesized caged antisense oligonucleoticles composed of phosphorothioated DNA or pepticle nucleic acid (PNA). The antiserise oligonucleoticle, which was attached to i a complementary blocking oligonuclecticle strand by a photocleavable linker, was blocked from binding target mRNA. This provided a useful method for photomodulating hybridization of the antisense. trancl to target mRNA. Caged DNA and PNA oligonucleoticles have proven effective at photoregulating gene expression in cells and zebrafish embryos.