title: Synthesis and gene silencing properties of siRNAs containing terminal amide linkages.
abstract: The active components of the RNAi are 21 nucleotides long dsRNAs containing a 2 nucleotide overhang at the 3' end, carrying 5'-phosphate and 3'-hydroxyl groups (siRNAs). Structural analysis revealed that the siRNA is functionally bound at both ends to RISC. Terminal modifications are considered with interest as the introduction of chemical moieties interferes with the 3' overhang recognition by the PAZ domain and the 5'-phosphate recognition by the MID and PIWI domains of RISC. Herein, we report the synthesis of modified siRNAs containing terminal amide linkages by introducing hydroxyethylglycine PNA (hegPNA) moieties at 5', and at 3' positions and on both terminals. Results of gene silencing studies highlight that some of these modifications are compatible with the RNAi machinery and markedly increase the resistance to serum-derived nucleases even after 24 h of incubation. Molecular docking simulations were attained to give at atomistic level a clearer picture of the effect of the most performing modifications on the interactions with the human Argonaute 2 PAZ, MID, and PIWI domains. This study adds another piece to the puzzle of the heterogeneous chemical modifications that can be attained to enhance the silencing efficiency of siRNAs.
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Gaglione
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: M Emilia
authors.initials: ME
authors.lastname: Mercurio
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Nicoletta
authors.identifier: 0000-0002-9736-792X
authors.initials: N
authors.lastname: Potenza
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Mosca
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Aniello
authors.identifier: 0000-0001-5421-3552
authors.initials: A
authors.lastname: Russo
authors.affiliation: Dipartimento di Chimica Farmaceutica e Tossicologica, Università "Federico II," Via D. Montesano 49, 80131 Napoli, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Novellino
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Sandro
authors.identifier: 0000-0002-8900-0968
authors.initials: S
authors.lastname: Cosconati
authors.affiliation: Dipartimento Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Messere
mesh_terms: D000577:Amides / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D062105:Molecular Docking Simulation; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000235:genetics*
chemical_list: D000577:Amides; D034741:RNA, Small Interfering; D008156:Luciferases