title: Enhancers of adeno-associated virus AAV2 transduction via high throughput siRNA screening.
abstract: Intracellular barriers to adeno-associated virus (AAV) transduction may limit gene delivery. We screened a short interfering RNA (siRNA) library targeting 5,520 genes to help identify pathways that modulate AAV transduction of human endothelium. In replicate screening, 50 pools (three siRNAs per gene) resulted in greater than eightfold reporter gene expression enhancement. Single siRNA confirmation tests demonstrated that at least one siRNA from each of the top 10 pools provided greater than twofold enhancement. Several siRNAs when used together resulted in additive effects and two of the most potent siRNA sequences were enhancers in cultured airway epithelium. However, enhanced transduction was not correlated with mRNA knockdown by quantitative real time PCR, indicating an off-target mechanism. In fact, four of the five most potent siRNAs contained a consensus hexamer region 5'-UGUUUC-3' at positions 2-7 of the antisense strand. The point mutation U4A within this region (but not mutations at positions 1 or 14) disrupted transduction enhancement, indicating a microRNA (miRNA)-like mechanism. Transcription profiling indicated that the hexamer also resulted in perturbation of the interferon pathway via reduced interferon-induced protein 44-like (IFI44L), interferon-inducible myxovirus resistance 1 (MX1), and interferon-induced protein with tetratricopeptide repeats (IFIT5) mRNAs. Direct interferon (α, β, and ω) receptor 2 (IFNAR2) knockdown resulted in greater than twofold transduction enhancement. In addition to providing insight into AAV biology and enhanced transduction, the results demonstrate certain beneficial siRNA off-target effects.
authors.affiliation: Penn Center for Molecular Discovery, Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, Philadelphia, Pennsylvania, USA.
authors.forename: Alexis J
authors.initials: AJ
authors.lastname: Wallen
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Barker
authors.forename: David E
authors.initials: DE
authors.lastname: Fein
authors.forename: Huiyan
authors.initials: H
authors.lastname: Jing
authors.forename: Scott L
authors.initials: SL
authors.lastname: Diamond
mesh_terms: D002460:Cell Line; D048429:Cell Size; D018118:Chloride Channels / Q000235:genetics; D000229:Dependovirus / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics; D006801:Humans; D064547:Myxovirus Resistance Proteins; D009363:Neoplasm Proteins / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051297:Sodium-Glucose Transporter 2 / Q000235:genetics
chemical_list: C108828:CLIC2 protein, human; D018118:Chloride Channels; C110985:IFIT5 protein, human; D064547:Myxovirus Resistance Proteins; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; C089180:SLC5A2 protein, human; D051297:Sodium-Glucose Transporter 2; D019204:GTP-Binding Proteins