title: RNA-induced silencing complex-bound small interfering RNA is a determinant of RNA interference-mediated gene silencing in mice.
abstract: Deeper knowledge of pharmacokinetic and pharmacodynamic (PK/PD) concepts for RNA therapeutics is important to streamline the drug development process and for rigorous selection of best performing drug candidates. Here we characterized the PK/PD relationship for small interfering RNAs (siRNAs) targeting luciferase by examining siRNA concentration in plasma and liver, the temporal RNA-induced silencing complex binding profiles, mRNA reduction, and protein inhibition measured by noninvasive bioluminescent imaging. A dose-dependent and time-related decrease in bioluminescence was detected over 25 days after a single treatment of a lipid nanoparticle-formulated siRNA targeting luciferase messenger RNA. A direct relationship was observed between the degree of in vivo mRNA and protein reduction and the Argonaute2 (Ago2)-bound siRNA fraction but not with the total amount of siRNA found in the liver, suggesting that the Ago2-siRNA complex is the key determinant of target inhibition. These observations were confirmed for an additional siRNA that targets endogenously expressed Sjögren syndrome antigen B (Ssb) mRNA, indicating that our observations are not limited to a transgenic mouse system. Our data provide detailed information of the temporal regulation of siRNA liver delivery, Ago2 loading, mRNA reduction, and protein inhibition that are essential for the rapid and cost-effective clinical development of siRNAs therapeutics.
authors.affiliation: Sirna Therapeutics, San Francisco, CA 94158, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Wei
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Jones
authors.forename: Jing
authors.initials: J
authors.lastname: Kang
authors.forename: Ananda
authors.initials: A
authors.lastname: Card
authors.forename: Michael
authors.initials: M
authors.lastname: Krimm
authors.forename: Paula
authors.initials: P
authors.lastname: Hancock
authors.forename: Yi
authors.initials: Y
authors.lastname: Pei
authors.forename: Brandon
authors.initials: B
authors.lastname: Ason
authors.forename: Elmer
authors.initials: E
authors.lastname: Payson
authors.forename: Natalya
authors.initials: N
authors.lastname: Dubinina
authors.forename: Mark
authors.initials: M
authors.lastname: Cancilla
authors.forename: Mark
authors.initials: M
authors.lastname: Stroh
authors.forename: Julja
authors.initials: J
authors.lastname: Burchard
authors.forename: Alan B
authors.initials: AB
authors.lastname: Sachs
authors.forename: Jerome H
authors.initials: JH
authors.lastname: Hochman
authors.forename: W Michael
authors.initials: WM
authors.lastname: Flanagan
authors.forename: Nelly A
authors.initials: NA
authors.lastname: Kuklin
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D020868:Gene Silencing; D051379:Mice; D008822:Mice, Transgenic; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering / Q000235:genetics*
chemical_list: D017931:DNA Primers; D034741:RNA, Small Interfering