title: Phosphorothioate antisense oligonucleotides induce the formation of nuclear bodies.
abstract: Antisense oligonucleotides are powerful tools for the in vivo regulation of gene expression. We have characterized the intracellular distribution of fluorescently tagged phosphorothioate oligodeoxynucleotides (PS-ONs) at high resolution under conditions in which PS-ONs have the potential to display antisense activity. Under these conditions PS-ONs predominantly localized to the cell nucleus where they accumulated in 20-30 bright spherical foci designated phosphorothioate bodies (PS bodies), which were set against a diffuse nucleoplasmic population excluding nucleoli. PS bodies are nuclear structures that formed in cells after PS-ON delivery by transfection agents or microinjection but were observed irrespectively of antisense activity or sequence. Ultrastructurally, PS bodies corresponded to electron-dense structures of 150-300 nm diameter and resembled nuclear bodies that were found with lower frequency in cells lacking PS-ONs. The environment of a living cell was required for the de novo formation of PS bodies, which occurred within minutes after the introduction of PS-ONs. PS bodies were stable entities that underwent noticeable reorganization only during mitosis. Upon exit from mitosis, PS bodies were assembled de novo from diffuse PS-ON pools in the daughter nuclei. In situ fractionation demonstrated an association of PS-ONs with the nuclear matrix. Taken together, our data provide evidence for the formation of a nuclear body in cells after introduction of phosphorothioate oligodeoxynucleotides.
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
authors.forename: P
authors.initials: P
authors.lastname: Lorenz
authors.forename: B F
authors.initials: BF
authors.lastname: Baker
authors.forename: C F
authors.initials: CF
authors.lastname: Bennett
authors.forename: D L
authors.initials: DL
authors.lastname: Spector
mesh_terms: D000941:Antigens / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D007424:Intracellular Fluid; D015530:Nuclear Matrix / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000378:metabolism / Q000494:pharmacology*; D013873:Thionucleotides / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000941:Antigens; D016376:Oligonucleotides, Antisense; D013873:Thionucleotides