Potent and nontoxic antisense oligonucleotides containing locked nucleic acids

Insufficient efficacy and/or specificity of antisense oligonucleotides limi t their in vivo usefulness. We demonstrate here that a high-affinity DNA an alog, locked nucleic acid (LNA), confers several desired properties to anti sense agents. Unlike DNA, LNA/DNA copolymers were not degraded readily in b lood serum and cell extracts. However, like DNA, the LNA/DNA copolymers wer e capable of activating RNase H, an important antisense mechanism of action . In contrast to phosphorothioate-containing oligonucleotides, isosequentia l LNA analogs did not cause detectable toxic reactions in rat brain. LNA/DN A copolymers exhibited potent antisense activity on assay systems as dispar ate as a C-protein-coupled receptor in living rat brain and an Escherichia coil reporter gene. LNA-containing oligonucleotides will likely be useful f or many antisense applications.