Showing papers by "Beverly L. Davidson published in 2013"

In vivo SELEX for Identification of Brain-penetrating Aptamers

Abstract: The physiological barriers of the brain impair drug delivery for treatment of many neurological disorders. One delivery approach that has not been investigated for their ability to penetrate the brain is RNA-based aptamers. These molecules can impart delivery to peripheral tissues and circulating immune cells, where they act as ligand mimics or can be modified to carry payloads. We developed a library of aptamers and an in vivo evolution protocol to determine whether specific aptamers could be identified that would home to the brain after injection into the peripheral vasculature. Unlike biopanning with recombinant bacteriophage libraries, we found that the aptamer library employed here required more than 15 rounds of in vivo selection for convergence to specific sequences. The aptamer species identified through this approach bound to brain capillary endothelia and penetrated into the parenchyma. The methods described may find general utility for targeting various payloads to the brain.

Gene Transfer of Human Apoe Isoforms Results in Differential Modulation of Amyloid Deposition and Neurotoxicity in Mouse Brain

Abstract: Inheritance of the e4 allele of apolipoprotein E ( APOE ) is the strongest genetic risk factor associated with the sporadic form of Alzheimer’s disease (AD), whereas the rare APOE e2 allele has the opposite effect However, the mechanisms whereby APOE confers risk and protection remain uncertain We used a gene transfer approach to bathe the cortex of amyloid plaque–bearing transgenic mice with virally expressed human APOE We monitored amyloid-β (Aβ) with multiphoton imaging, in vivo microdialysis, and postmortem array tomography to study the kinetics of human APOE-mediated changes in Aβ-related neurotoxicity in a mouse model of AD We observed that human APOE4 increased the concentrations of oligomeric Aβ within the interstitial fluid and exacerbated plaque deposition; the converse occurred after exposure to human APOE2 Peri-plaque synapse loss and dystrophic neurites were also worsened by APOE4 or attenuated by APOE2 Egress of Aβ from the central nervous system (CNS) into the plasma was diminished by APOE3 and APOE4 compared to APOE2, in accord with isoform-specific retention of Aβ in the CNS Overall, our data show a differential effect of human APOE isoforms on amyloid deposition and clearance in transgenic mice and, more importantly, on Aβ-mediated synaptotoxicity These results suggest that the APOE genetic risk is mediated by Aβ, and that therapeutic approaches aimed at decreasing APOE4, or increasing APOE2, may be beneficial in AD

CLN3 loss disturbs membrane microdomain properties and protein transport in brain endothelial cells.

Abstract: Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal childhood-onset neurodegenerative disorder caused by mutations in ceroid lipofuscinosis neuronal-3 (CLN3), a hydrophobic transmembrane protein of unresolved function. Previous studies indicate blood–brain barrier (BBB) defects in JNCL, and our earlier report showed prominent Cln3 expression in mouse brain endothelium. Here we find that CLN3 is necessary for normal trafficking of the microdomain-associated proteins caveolin-1, syntaxin-6, and multidrug resistance protein 1 (MDR1) in brain endothelial cells. Correspondingly, CLN3-null cells have reduced caveolae, and impaired caveolae- and MDR1-related functions including endocytosis, drug efflux, and cell volume regulation. We also detected an abnormal blood–brain barrier response to osmotic stress in vivo. Evaluation of the plasma membrane with fluorescent sphingolipid probes suggests microdomain destabilization and enhanced fluidity in CLN3-null cells. In further work we found that application of the glycosphingolipid lactosylceramide to CLN3-deficient cells rescues protein transport and caveolar endocytosis. Last, we show that CLN3 localizes to the trans-Golgi network (TGN) and partitions with buoyant microdomain fractions. We propose that CLN3 facilitates TGN-to-plasma membrane transport of microdomain-associated proteins. Insult to this pathway may underlie BBB dysfunction and contribute to JNCL pathogenesis.

siSPOTR: a tool for designing highly specific and potent siRNAs for human and mouse

Abstract: RNA interference (RNAi) serves as a powerful and widely used gene silencing tool for basic biological research and is being developed as a therapeutic avenue to suppress disease-causing genes. However, the specificity and safety of RNAi strategies remains under scrutiny because small inhibitory RNAs (siRNAs) induce off-target silencing. Currently, the tools available for designing siRNAs are biased toward efficacy as opposed to specificity. Prior work from our laboratory and others’ supports the potential to design highly specific siRNAs by limiting the promiscuity of their seed sequences (positions 2–8 of the small RNA), the primary determinant of off-targeting. Here, a bioinformatic approach to predict off-targeting potentials was established using publically available siRNA data from more than 50 microarray experiments. With this, we developed a specificity-focused siRNA design algorithm and accompanying online tool which, upon validation, identifies candidate sequences with minimal off-targeting potentials and potent silencing capacities. This tool offers researchers unique functionality and output compared with currently available siRNA design programs. Furthermore, this approach can greatly improve genome-wide RNAi libraries and, most notably, provides the only broadly applicable means to limit off-targeting from RNAi expression vectors.

Efficient delivery of RNA interference oligonucleotides to polarized airway epithelia in vitro.

Abstract: Polarized and pseudostratified primary airway epithelia present barriers that significantly reduce their transfection efficiency and the efficacy of RNA interference oligonucleotides. This creates an impediment in studies of the airway epithelium, diminishing the utility of loss-of-function as a research tool. Here we outline methods to introduce RNAi oligonucleotides into primary human and porcine airway epithelia grown at an air-liquid interface and difficult-to-transfect transformed epithelial cell lines grown on plastic. At the time of plating, we reverse transfect small-interfering RNA (siRNA), Dicer-substrate siRNA, or microRNA oligonucleotides into cells by use of lipid or peptide transfection reagents. Using this approach we achieve significant knockdown in vitro of hypoxanthine-guanine phosphoribosyltransferase, IL-8, and CFTR expression at the mRNA and protein levels in 1–3 days. We also attain significant reduction of secreted IL-8 in polarized primary pig airway epithelia 3 days posttransfection and inhibition of CFTR-mediated Cl− conductance in polarized air-liquid interface cultures of human airway epithelia 2 wk posttransfection. These results highlight an efficient means to deliver RNA interference reagents to airway epithelial cells and achieve significant knockdown of target gene expression and function. The ability to reliably conduct loss-of-function assays in polarized primary airway epithelia offers benefits to research in studies of epithelial cell homeostasis, candidate gene function, gene-based therapeutics, microRNA biology, and targeting the replication of respiratory viruses.

In vivo delivery of DN:REST improves transcriptional changes of REST-regulated genes in HD mice.

Abstract: In vivo delivery of DN:REST improves transcriptional changes of REST-regulated genes in HD mice

Methods and compositions for treating amyloid deposits

Abstract: The present disclosure provides methods of delivering a protective ApoE isoform to the central nervous system of a mammal, comprising administering to the cerebrospinal fluid (CSF) of the mammal an rAAV particle comprising an AAV capsid protein and a vector comprising a nucleic acid encoding the protective ApoE isoform inserted between a pair of AAV inverted terminal repeats in a manner effective to infect ependymal cells in the non-rodent mammal such that the ependymal cells secrete the ApoE into the CSF of the mammal.

Modified adeno-associated virus vector compositions

Abstract: An adeno-associated virus filler component comprising a nucleic acid of between 3300 and 4200 nucleotides in length is disclosed.

Methods to enhance RNAi oligonucleotide delivery to respiratory epithelial cells

Abstract: The present invention relates to methods of reducing a level of a target mRNA in a well-differentiated airway epithelial cell by contacting the cell with a sensitizing agent followed by contacting the cell with a therapeutic RNAi agent.

Method of delivering vectors to pancreas and lungs by cannulating the aorta

Abstract: The present invention relates to a safe and effective way to deliver and express therapeutic compositions (e.g., transgenes) to the pancreas and lungs of a mammal.