In multicellular organisms, cell growth and differentiation is controlled in part by apoptosis. One major apoptotic pathway is triggered by Fas receptor (Fas)-Fas ligand (FasL) interaction. Resistance to Fas-mediated apoptosis is regulated through the production of a soluble Fas isoform (sFas), created by exclusion of transmembrane spanning sequences encoded within exon 6 (FasΔ6) that can bind FasL and block apoptosis. Long noncoding RNAs (lncRNAs) are >200-nucleotide sequences that are important regulators of cellular programs. However, their role in erythropoiesis is just beginning to be appreciated with studies limited to murine systems. I studied the potential role of lncRNAs during human red blood cell development using RNA from cultured CD34+ purified from fetal liver (FL), cord blood (CB), or adult bone marrow (BM) to screen 82 documented lncRNAs. This screen revealed that the Fas Anti-sense (Saf) was consistently increased during maturation and levels high for BM compared to FL or CB. Next, I characterized the regulatory sequence of Saf and by In silico analysis identified canonical binding sites for the erythroid-specific transcription factors KLF1 and GATA1. Chromatin immunoprecipitation (ChIP) assays confirmed binding of both factors to their target sequences and luciferase reporter constructs revealed synergistic activity evidenced by increase in luciferase expression relative to controls. Genome wide expression analysis using cells with overexpression of Saf showed no effect on global gene transcription, suggesting Saf function at post transcriptional levels. Saf was shown to participate in alternative splicing of Fas pre-mRNA through unknown mechanisms. Using a combination of biochemical assays, overexpression and knockdown studies, I showed how this occurs. Cell fractionation and RT-PCR demonstrated that Saf is localized in the nucleus. I found that Saf directly interacted with Fas pre-mRNA to form RNaseA-resistant double-stranded RNA intermediates at regions that flank Exon6. Post-transcriptional function of Saf was confirmed by qRT-PCR demonstrating significantly increased levels of sFas for Saf overexpressing cells. Enrichment for sFas RNA coincided with reduced Fas on the cell surface and increased sFas protein levels when conditioned supernatants were assayed by ELISA. Conversely, siRNA-mediated knockdown of Saf significantly reduced sFas production compared to non-targeting siRNA controls. Saf-interacting proteins were identified by mixing in vitro transcribed and biotin-labeled Saf RNA with nuclear lysates followed by mass spectrometry analysis. This screen identified human splicing factor 45 (SPF45) which has a known role in Fas pre-mRNA alternative splicing. Specific SPF45/Saf interaction was confirmed by RNA pulldown and western blot with SPF45-specific antibodies and the ability to detect sequences for Saf, Fas and sFas by RT-PCR of RNA that immunoprecipitated with SPF45. SPF45 knockdown decreased sFas transcripts and this reduction corresponded to limited production of sFas and increased sensitivity to Fas-mediated apoptosis when cells were exposed to the Fas-activating antibody CH11. Importantly, overexpression of Saf in SPF45 knockdown cells failed to rescue production of sFas supporting the hypothesis that Saf and SPF45 co-participate in modulating Fas pre-mRNA splicing. Protein phosphorylation modulates the interaction of the splicing factors with RNA. The effect of phosphorylation on the Saf-SPF45 interaction was evaluated using stable cell lines expressing a myc-tagged SPF45 protein or versions modified to introduce alanine in place of threonine 71 (T-71-A) or serine 222 (S-222-A) to prevent phosphorylation. Mutation in S-222-A reduced the interaction of SPF45 with Saf. I conclude that Saf interacts with Fas pre-mRNA at sequences that flank exon 6 and recruits phosphorylated SPF45 as mechanism to recognize exon 6 and allow for alternative splicing of Fas Pre-mRNA. Collectively, these studies reveal a novel mechanism to regulate apoptosis that may be responsible for cell proliferation and drug resistance.

No description available.

Damage to the adult mammalian central nervous system (CNS), either by traumatic injury or disease, usually results in permanent sensory and/or motor deficits. Regeneration of neural circuits is limited both by the lack of growthpromoting molecules and by the presence of growth-inhibitory molecules in the mature brain and spinal cord. The research described here examines the therapeutic potential of viral vectors and neuronal transplants to reconstruct damaged neural pathways in the CNS. Experimental neural transplantation techniques often fall short of expectations because of limited transplant survival and insufficient neurite outgrowth to repair connections and induce behavioral recovery. These shortcomings are addressed in the current studies by virus-mediated expression of cell-specific neurotrophic and guidance molecules in the host brain prior to cell transplantation. The initial proof-of-principle studies show that viral vectors can be used to create axon-guidance pathways in the adult mammalian brain. With such pathways in place, subsequent transplantation of neurons leads to longdistance, targeted outgrowth of neurites. Application of this technique to a rat model of Parkinsons disease demonstrates that circuit reconstruction leads to functional recovery. For this study, rats were lesioned on one side of their brain with 6-hydroxydopamine to produce a hemiparkinsonian state. The motor deficit was confirmed by amphetamine-induced rotation testing and spontaneous motor asymmetry testing. The rats were then divided into experimental groups to receive lentivirus injections along a path between the substantia nigra (SN) and the striatum to express glial cell-line derived neurotrophic factor (GDNF), GDNF family receptor alpha-1 (GFR1), netrin-1 or green fluorescent protein (GFP, control). One group received combination injections of lenti-GDNF and lenti-GFR1. One week after virus injections, animals received transplants of embryonic midbrain dopaminergic neurons into their SNs. They were tested for motor asymmetry every two weeks for a total of eight weeks and then brain tissue was harvested for immunohistochemical analysis. Results demonstrate that virus-induced expression of GDNF and GFR1 supports growth of dopaminergic fibers from cells transplanted into the SN all the way to the striatum, and these animals have a significant reduction in both drug-induced and spontaneous motor asymmetry.

Replication defective adenoviruses have emerged as promising vectors for delivery of vaccine antigens. The development of new vaccine vectors has recently focused on serotypes t, which the human population is less exposed in order to circumvent pre-existing anti vector immunity. This thesis describes the construction and optimisation of ChAdOX1, a new vector based on chimpanzee adenovirus Y2S, which has recently been manufactured to clinical grade for a Phase 1 human trial. Comparative immunogenicity studies between vectors of different serotype were performed in mice, with careful consideration of the infectious titer of vector preparations, since this parameter can confound studies based solely on viral particle estimation. Aft intramuscular administration, HAdV-S (Human adenovirus C) based vectors elicited superior transgene product specific T cell and antibody responses compared to a selection of chimpanzee adenovirus vectors (from Human adenovirus EJ including ChAdOX1. The construction of ChAdOXl in a bacterial artificial chromosome (BA C), enabled precise, and flexible modification of the genome by recombmation mediated genetic engineering. (recombmeering). Reverse genetics was performed to identify vector determinants of immunogenicity. Chimeric ChAdOXl vectors were created by replacement of native virus associated RNA (VA-RNA) and fiber sequences with the corresponding sequences from HAdV-5 Using these chimeric vectors, the importance of innate immunity and vector transduction in determining vector immunogenicity was investigated. Though the mechanisms responsible ultimately remain unclear, superior transgene product specific immune responses with HAdV-5 correlated with higher levels of transgene expression in vivo after vector administration. The current study has conclusively demonstrated that neither VA-RNA sequences, nor the fiber protein, are responsible for differences in immunogenicity between vectors, contrary to hypotheses based on previous studies.

Parkinson's disease is characterized by progressive degeneration of substantia nigra (SN) and subsequently loss of the nigrostriatal circuit. Many strategies have attempted to reconstruct this circuit but failed to satisfy clinical trials. The inhibitory environment of the adult CNS and the long distance between the SN and the striatum make true reconstruction difficult. To reconstruct this circuit, we used a transplant-pathway targeting model. Several putative pathway targeting molecules were examined for their ability to direct the growth of axons from a dopaminergic transplant. For a proof-of-principle study, adenoviral and lentiviral encoded glial cell line-derived neurotrophic factor (GDNF), GDNF-receptor alpha1 (GFRa1 ), or netrin-1 were injected along the corpus callosum individually or in combination. Treatment with individual factors leads to modest growth with few axons extending the entire length of the pathway. Combined treatment with either GDNF/GFRa1 or GDNF/netrin-1 induced the most robust growth towards the contralateral striatum. GDNF/netrin-1 showed the most consistent growth, with about 80% of the axons growing to the farthest injection site on the contralateral side. To determine if this combination of guidance molecules could be used to reconstruct the nigrostriatal pathway, we examined axon outgrowth from transplants placed within the SN in the 6-0HDA-Iesioned hemiparkinsonian animal model. A pathway from the SN to the striatum was made by injecting lentivirus encoding either GDNF and netrin-1 or GDNF and GFRa1, along the internal capsule, from the SN to the striatum. In another cohort of animals lentivirus encoding GFP was used as a control. A piece of embryonic VM tissue was transplanted into the SN two weeks after lentivirus injections. Compare to the GFP control group, a significantly greater number of dopaminergic axons grew from the transplants towards the striatum ten weeks after transplantation. Retrograde tract tracing showed the dopaminergic axons were from A9 cells in the transplant. Behavioral studies showed a significant reduction in number of amphetamine-induced rotations in GDNF/netrin-1 treated animals. Functional recovery strongly correlated with the number of dopaminergic fibers growing out from the transplant. This study shows that a functional nigrostriatal pathway can be reconstructed by guiding axonal growth from the dopaminergic neurons transplanted in the SN along a preformed growth-supportive pathway extending into the striatum. Refinement of this technique could be beneficial for PD patients in the future.

Cystic fibrosis (CF) is the most common autosomal recessive genetic disease in Caucasian populations. CF affects multiple organ systems including pancreas, liver, intestines, sweat glands, and male reproductive organs, however the leading cause of morbidity and mortality in CF patients is chronic lung disease. CF is caused by a mutant cystic fibrosis transmembrane conductance regulator (CFTR) gene which leads to chloride (Cl-) and bicarbonate (HCO3-) anion dysregulation at the airway surface. Without adequate anion exchange, thick, viscous mucus accumulates at the airway surface allowing bacterial colonization to occur. Complementing CFTR in the appropriate airway cells restores the anion channel activity in CFTR-deficient cells. The ultimate goal for CF gene therapy is to design an integrating vector that would lead to persistent and efficient expression of CFTR in the airways. Performing gene therapy experiments is dependent upon a relevant animal model. The CF pig is a large animal model similar in size, anatomy, and physiology to humans. Importantly, the CF pig recapitulates human lung disease. From the CF pig, we have learned much about CF lung disease and have developed relevant assays to measure anion channel correction. We have learned that loss of CFTR leads to a decreased airway surface ASL pH, bacterial killing ability, and increased mucus viscosity. Standardized assays have been developed to evaluate the change in current by Ussing chambers, ASL pH, bacterial killing in vivo and ASL pH and viscosity on primary airway cultures in vitro. Ultimately, these metrics allow us to make conclusions about the efficiency of CFTR restoration. Viral vectors are promising candidates for CF gene therapy. Viral vectors such as adenovirus (Ad), adeno-associated virus (AAV), and pseudotyped lentiviral vectors such as feline immunodeficiency virus (FIV) or human immunodeficiency virus (HIV) can efficiently transduce airway cells and express CFTR. Ad and AAV have both been tested in CF clinical trials, but CFTR expression was transient, if detected at all. Understanding vector biology and overcoming barriers in the lung have allowed us to improve vector delivery to the airways. However, the next major hurdle was achieving persistent expression. Ad and AAV are both transiently expressing vectors, and vector readministration is implausible due to the presence of neutralizing antibodies that develop against the vector. Creating a hybrid nonviral/viral vector in which the integrating nonviral piggyBac transposon system is delivered by an Ad or AAV vector has allowed us to achieve persistent expression in mice. In a third integrating vector system, lentiviral vectors have historically been challenging to work with due to low titer levels. However, improvement in vector purification methods have allowed us to validate a lentiviral vector as a viable gene therapy option. In total, we have validated three integrating vector systems by restoring CFTR to CF pigs to correct the phenotypic defect.

Hearing impairment is the most common sensory deficit worldwide, affecting at least one child in every one thousand born. Gene therapy targeting the inner ear offers promise for treatment of genetic forms of hearing loss. Many genetic forms of deafness are congenital and gene therapies in these cases would require treatment prior to inner ear maturation. Included in this category is the dominant-negative R75W mutation in GJB2 which encodes connexin 26, a gap junction protein expressed in the supporting cells of the organ of Corti. RNA interference (RNAi)-based therapeutics offer promise for treating dominant-negative diseases. Our goal has been the in vivo application of RNAi-therapy to the GJB2-R75W transgenic mouse, a model of severe-to-profound dominant-negative hearing loss. Here we describe our efforts to identify a therapeutic, a suitable delivery route, and an optimal delivery vector. We have designed and optimized siRNA to achieve robust silencing of the mutant transgene in vitro and have prepared artificial miRNA constructs for in vivo application. We have determined to use the embryonic otocyst microinjection technique as the route for therapeutic delivery and have successfully utilized this technique to study the tropism and safety of several viral vector (adeno-associated virus 2/1, early- and late-generation adenoviruses, and bovine adeno-associated virus). For the first time we have characterized viral tropism for cochlear supporting cells following in utero delivery to their progenitor cells in the developing cochlea and identified bovine adeno-associated virus as a safe vector for gene delivery to the supporting cells of the cochlea. We have also described two previously unreported phenotypes in the GJB2-R75W transgenic mouse model: skin disease and cataracts. Both can be caused by dominant connexin mutations in humans. Our work shows that although gene therapy is not simple, powerful tools are in place for treating dominant forms of hereditary hearing loss.

This thesis explores the capabilities of cationic polymers modified with lipids of different carbon chain length to deliver DNA molecules to primary cells and transformed cell lines. Our studies focus on two different polymers: polyethylenimine (PEI) and poly(L-lysine) (PLL). Firstly, PEI and PLL were conjugated to palmitic acid (C16). The delivery of plasmid DNA to rat bone marrow stromal cells (rat-BMSC) was evaluated by using a Green Fluorescent Protein gene expressing plasmid (pEGFP-N2) as a reporter system. The rationale for lipid substitution is to give the polymer an amphiphilic character so as to improve the transfection efficiency of native polymers by improving the DNA/polymer translocation through the phospholipid-rich cell membranes. In the case of PLL-C16, transfection efficiency was significantly increased (5 fold) as compared to native PLL, and it was significantly higher than commercially available cationic lipids (LipofectamineTM 2000 and FugeneTM). We further explore the use of other lipids with variable chain lengths (carbon chain length ranging from 8 to 18 saturated and unsaturated) in order to identify other candidates to enhance the gene delivery properties of the PLL. Lipid-modified PLL of high molecular weight (25 vs. 4 kDa) was found to be more effective in delivering plasmid DNA in rat-BMSC. We noted that C14-, C16- and C18-substituted PLL gave the most effective DNA delivery. Moreover, a correlation between the extent of lipid substitution and the plasmid DNA delivery efficiency was found Additionally, transgene expression by BMSC significantly increased when amphiphilic PLLs were used as compared to native PLL. The modified polymers were able to transfect the cells up to 7 days, after which the expression decreased. Encouraged by the successful transgene expression agents obtained by modifying low molecular weight PEI with the same series of lipids described above, we explored the possibility of modifying low molecular weight PEI (2 kDa) with longer lipids; saturated fatty acid (C22), trans fat (C18:1T) and essential fatty acids (C22:1, C22:6 and C18:3). Transfection efficiency proved to be cell dependent. Only the transformed 293T cells were able to express GFP compared to human-derived BMSC. The highest transfection efficiency was found with highly unsaturated lipid-substituted PEI (C18:3 and C22:6) and were able to increase transgene expression overtime (6 days). Furthermore, internalization studies indicated that effective transfection of these carries do not follow any known endocytosis pathway instead the DNA/carrier penetrates the plasma membrane directly. / Pharmaceutical Sciences

During an adenovirus infection the accumulation of alternatively spliced mRNAs is subjected to a tight temporal regulation. The IIIa protein is a structural protein expressed exclusively late after infection. To study the significance of the restricted IIIa protein expression we used a Tet-ON regulated adenoviral vector to overexpress the IIIa protein during the early phase of infection. The results show that unregulated IIIa protein expression caused a reduction in late viral protein accumulation and a slight block of viral DNA replication. Further, the results indicate that IIIa splicing might be subjected to a regulation via a feed back loop stimulating its own expression. To improve the efficacy of vectors for regulated transgene expression, we constructed binary adenoviral vectors based on the Tet-ON and Tet-OFF systems. These vectors encode both the transcriptional activator and the tetracycline-regulated expression cassette from the same viral unit, ensuring that each infected cell will express both the activator and the reporter gene. In model experiments this system was shown to result in a tight control of gene expression with no detectable background expression of the transgene and induction levels reaching 500-600 fold. Introduction of dsRNA into a cell will induce a sequence specific degradation of the homologous mRNA via a mechanism named RNA interference (RNAi). The adenovirus VA RNAs are short highly structured RNAs that are expressed in large amounts late during an adenovirus infection. Here we showed that both VA RNAI and VA RNAII functions as virus-encoded suppressors of RNAi, by interfering with the activity of Dicer, the enzyme that cleaves the initial dsRNA to short-interfering RNAs (siRNAs) that mediate RNAi. Further, the VA RNAs themselves are substrates for Dicer and are cleaved into siRNAs in vivo that are incorporated into active RNA-induced silencing complexes. There is a great interest in developing novel therapeutic strategies based on RNAi. We constructed adenoviral vectors that express short hairpin RNAs, which in vivo will be cleaved to siRNAs that induce sequence-specific RNAi. We compared the efficiency of RNAi induced by vectors based on the viral VA RNAI and the human U6 promoters. Our results suggest that under conditions where the recombinant virus does not replicate, the VA RNA promoter is more effective in down regulating target gene expression, whereas the U6 promoter was more effective under replicative conditions.

The helper-dependent adenoviral (HD-Ad) vector is the latest generation of Ad vectors. It ameliorates the vector-associated immunogenic problems with increased capacity for carrying DNA because all viral coding genes are removed. I hypothesize that HD-Ad vectors can be effective vehicles for retinal gene delivery. The objectives of this study are to determine if HD-Ad vectors can deliver reporter genes, GFP or lacZ, driven by a CMV or a MOPS promoter, into specific retinal layers. Subretinal injections were performed and eyes removed at time points from 1 week to 3 months, processed for fluorescent microscopy, X-gal staining, and H&E staining. Transgene expression was detected for at least 3 months. A dose dependent relationship was revealed between the level of transgene expression and viral vector dose. Distinctively, the MOPS promoter drove photoreceptor cell specific expression. Notably, no sign of inflammation or tissue toxicity was detected, demonstrating the benefits of the HD-Ad vector.