title: Transcription factor decoy oligonucleotides modified with locked nucleic acids: an in vitro study to reconcile biostability with binding affinity.
abstract: Double-stranded oligonucleotides (ODNs) containing the consensus binding sequence of a transcription factor provide a rationally designed tool to manipulate gene expression at the transcriptional level by the decoy approach. However, modifications introduced into oligonucleotides to increase stability quite often do not guarantee that transcription factor affinity and/or specificity of recognition are retained. We have previously evaluated the use of locked nucleic acids (LNA) in the design of decoy molecules for the transcription factor kappaB. Oligo nucleotides containing LNA substitutions displayed high resistance to exo- and endonucleolytic degradation, with LNA-DNA mix-mers being more stable than LNA-DNA-LNA gap-mers. However, insertion of internal LNA bases resulted in a loss of affinity for the transcription factor. This latter effect apparently depended on positioning of the internal LNA substitutions. Indeed, here we demonstrate that intra- and inter-strand positioning of internal LNAs has to be carefully considered to maintain affinity and achieve high stability, respectively. Unfortunately, our data also indicate that LNA positioning is not the only parameter affecting transcription factor binding, the interference in part being dependent on the intrinsic conformational properties of this nucleotide analog. To circumvent this problem, the successful use of an alpha-L-ribo- configured LNA is demonstrated, indicating LNA-DNA-alpha-L-LNA molecules as promising new decoy agents.
authors.affiliation: Istituto di Chimica Biologica G. Fornaini, Università degli Studi di Urbino Carlo Bo, Via Saffi 2, I-61029 Urbino, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Crinelli
authors.forename: Marzia
authors.initials: M
authors.lastname: Bianchi
authors.forename: Lucia
authors.initials: L
authors.lastname: Gentilini
authors.forename: Linda
authors.initials: L
authors.lastname: Palma
authors.forename: Mads D
authors.initials: MD
authors.lastname: Sørensen
authors.forename: Torsten
authors.initials: T
authors.lastname: Bryld
authors.forename: Ravindra B
authors.initials: RB
authors.lastname: Babu
authors.forename: Khalil
authors.initials: K
authors.lastname: Arar
authors.forename: Jesper
authors.initials: J
authors.lastname: Wengel
authors.forename: Mauro
authors.initials: M
authors.lastname: Magnani
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D004720:Endonucleases / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense; D014157:Transcription Factors; C477371:locked nucleic acid; D004720:Endonucleases; D005092:Exonucleases