Cross-species evolution of a highly potent AAV variant for therapeutic gene transfer and genome editing.

Recombinant adeno-associated viral (AAV) vectors are a promising gene delivery platform, but ongoing clinical trials continue to highlight a relatively narrow therapeutic window. Effective clinical translation is confounded, at least in part, by differences in AAV biology across animal species. Here, we tackle this challenge by sequentially evolving AAV capsid libraries in mice, pigs and macaques.

Long-term evaluation of AAV-CRISPR genome editing for Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a monogenic disorder and a candidate for therapeutic genome editing. There have been several recent reports of genome editing in preclinical models of Duchenne muscular dystrophy, however, the long-term persistence and safety of these genome editing approaches have not been addressed. Here we show that genome editing and dystrophin protein restoration is sustained in the mdx mouse model of Duchenne muscular dystrophy for 1 year after a single intravenous administration of an adeno-associated virus that encodes CRISPR (AAV-CRISPR).

Aquaporin-4-dependent glymphatic solute transport in the rodent brain.

The glymphatic system is a brain-wide clearance pathway; its impairment contributes to the accumulation of amyloid-β. Influx of cerebrospinal fluid (CSF) depends upon the expression and perivascular localization of the astroglial water channel aquaporin-4 (AQP4). Prompted by a recent failure to find an effect of knock-out (KO) on CSF and interstitial fluid (ISF) tracer transport, five groups re-examined the importance of AQP4 in glymphatic transport.

Tissue-Dependent Expression and Translation of Circular RNAs with Recombinant AAV Vectors In Vivo.

Circular RNAs (circRNAs) are long-lived, covalently closed RNAs that are abundantly expressed and evolutionarily conserved across eukaryotes. Possible functions ranging from microRNA (miRNA) and RNA binding protein sponges to regulators of transcription and translation have been proposed. Here we describe the design and characterization of recombinant adeno-associated viral (AAV) vectors packaging transgene cassettes containing intronic sequences that promote backsplicing to generate circularized RNA transcripts.

Mapping the Structural Determinants Required for AAVrh.10 Transport across the Blood-Brain Barrier.

Effective gene delivery to the CNS by intravenously administered adeno-associated virus (AAV) vectors requires crossing the blood-brain barrier (BBB). To achieve therapeutic CNS transgene expression, high systemic vector doses are often required, which poses challenges such as scale-up costs and dose-dependent hepatotoxicity. To improve the specificity and efficiency of CNS gene transfer, a better understanding of the structural features that enable AAV transit across the BBB is needed.

Structure-guided evolution of antigenically distinct adeno-associated virus variants for immune evasion.

Preexisting neutralizing antibodies (NAbs) against adeno-associated viruses (AAVs) pose a major, unresolved challenge that restricts patient enrollment in gene therapy clinical trials using recombinant AAV vectors. Structural studies suggest that despite a high degree of sequence variability, antibody recognition sites or antigenic hotspots on AAVs and other related parvoviruses might be evolutionarily conserved. To test this hypothesis, we developed a structure-guided evolution approach that does not require selective pressure exerted by NAbs.

In vivo genome editing improves muscle function in a mouse model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a devastating disease affecting about 1 out of 5000 male births and caused by mutations in the dystrophin gene. Genome editing has the potential to restore expression of a modified dystrophin gene from the native locus to modulate disease progression. In this study, adeno-associated virus was used to deliver the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system to the mdx mouse model of DMD to remove the mutated exon 23 from the dystrophin gene.

Functional analysis of the putative integrin recognition motif on adeno-associated virus 9.

Adeno-associated viruses (AAVs) display a highly conserved NGR motif on the capsid surface. Earlier studies have established this tripeptide motif as being essential for integrin-mediated uptake of recombinant AAV serotype 2 (AAV2) in cultured cells. However, functional attributes of this putative integrin recognition motif in other recombinant AAV serotypes displaying systemic transduction in vivo remain unknown.

Recombination signal binding protein for Ig-κJ region regulates juxtaglomerular cell phenotype by activating the myo-endocrine program and suppressing ectopic gene expression.

Recombination signal binding protein for Ig-κJ region (RBP-J), the major downstream effector of Notch signaling, is necessary to maintain the number of renin-positive juxtaglomerular cells and the plasticity of arteriolar smooth muscle cells to re-express renin when homeostasis is threatened. We hypothesized that RBP-J controls a repertoire of genes that defines the phenotype of the renin cell. Mice bearing a bacterial artificial chromosome reporter with a mutated RBP-J binding site in the renin promoter had markedly reduced reporter expression at the basal state and in response to a homeostatic challenge.

Transcriptional regulator RBP-J regulates the number and plasticity of renin cells.

Renin-expressing cells are crucial in the control of blood pressure and fluid-electrolyte homeostasis. Notch receptors convey cell-cell signals that may regulate the renin cell phenotype. Because the common downstream effector for all Notch receptors is the transcription factor RBP-J, we used a conditional knockout approach to delete RBP-J in cells of the renin lineage.