title: Impact of the guanidinium group on hybridization and cellular uptake of cationic oligonucleotides.
abstract: The grafting of cationic groups to synthetic oligonucleotides (ONs) in order to reduce the charge repulsion between the negatively charged strands of a duplex or triplex, and consequently to increase a complex's stability, has been extensively studied. Guanidinium groups, which are highly basic and positively charged over a wide pH range, could be an efficient ON modification to enhance their affinity for nucleic acid targets and to improve cellular uptake. A straightforward post-synthesis method to convert amino functions attached to ONs (on sugar, nucleobase or backbone) into guanidinium tethers has been perfected. In comparison to amino groups, such cationic groups anchored to alpha-oligonucleotide phosphoramidate backbones play important roles in duplex stability, particularly with RNA targets. This high affinity could be explained by dual recognition resulting from Watson-Crick or Hoogsteen base pairing combined with cationic/anionic backbone recognition between strands involving H-bond formation and salt bridging. Molecular-dynamics simulations corroborate interactions between the cationic backbones of the alpha-ONs and the anionic backbones of the nucleic acid targets. Moreover, ONs with guanidinium modification increased cellular uptake relative to negatively charged ONs. The cellular localization of these new cationic phosphoramidate ONs is mainly cytoplasmic. The uptake of these ON analogues might occur through endocytosis.
authors.affiliation: LCOBS, UMR 5625 CNRS-UMII, CC 008, Université Montpellier II, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Deglane
authors.forename: Saïd
authors.initials: S
authors.lastname: Abes
authors.forename: Thibaut
authors.initials: T
authors.lastname: Michel
authors.forename: Paul
authors.initials: P
authors.lastname: Prévot
authors.forename: Eric
authors.initials: E
authors.lastname: Vives
authors.forename: Françoise
authors.initials: F
authors.lastname: Debart
authors.forename: Ivan
authors.initials: I
authors.lastname: Barvik
authors.forename: Bernard
authors.initials: B
authors.lastname: Lebleu
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Vasseur
mesh_terms: D002412:Cations / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry / Q000187:drug effects; D019791:Guanidine / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics*; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry / Q000187:drug effects; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D002412:Cations; D009841:Oligonucleotides; D012313:RNA; D004247:DNA; D019791:Guanidine