CpG islands (CGIs) are short GC rich sequences with a high frequency of CpGs that are associated with the active chromatin mark H3K4me3. Most occur at gene promoters and are often free of cytosine methylation. Recent work has begun to clarify the functional significance of CGIs with respect to chromatin structure and transcription. In particular, proteins associated with histone-modifying activities, such as Cfp1 and Kdm2a, bind specifically to non-methylated CGIs via their CxxC domains. For example, artificial promoterless CpG-rich sequences integrated at the 3’ UTR of genes recruit Cfp1 and generate novel peaks of H3K4me3 in mouse ES cells without apparent RNA polymerase recruitment. There is also evidence that G+C-rich DNA recruits H3K27me3, a gene silencing mark. In this thesis I am exploring the constraints on DNA sequence and genomic location that are required to impose both H3K4me3 and H3K27me3 at CGI sequences. Showing that the generation of novel peaks of H3K4me3 and H3K27me3 over a promoter-less CpG rich sequence in a gene desert region is independent of it’s location in the genome extends earlier findings. These findings suggest that shared features of the primary DNA sequence at CGIs directly influence chromatin modification. Thus CGIs are not passive footprints of other cellular mechanisms, but play an active role in setting up local chromatin structure. However, the relative contribution of CpG frequency versus G+C content remains unclear. Therefore a sequence was generated that contains low levels of CpGs, comparable to the bulk genome, but has a G+C content similar to that of CGIs (Low CpG / High G+C). When this sequence was inserted into a gene desert neither marks of H3K4me3 or H3K27me3 were formed, indicating the importance of CpGs. Surprisingly, the reverse sequence with a high CpG frequency similar to that of CGIs and a low G+C content similar to that of the bulk genome (High CpG / Low G+C) did not establish H3K4me3 or H3K27me3 either. However, it was found that this sequence becomes heavily methylated in contrast to CGI-like sequences that remained unmethylated when introduced into a gene desert. This finding suggests that a high G+C content is important for keeping CGI-like sequences methylation free. Upon insertion of this High CpG / Low G+C sequence into mouse ES cells that were devoid of the de-novo DNA methyltransferases 3a and 3b (Dnmt3a/3b -/-) both H3K4me3 and H3K27me3 marks were established at the inserted sequence. This discovery confirms the importance of CpGs for setting up local chromatin structure.

The Centromere is a vital chromosomal structure that ensures faithful segregation of replicated chromosomes to their respective daughter cells. With such an important structure, one would expect the underlying centromeric DNA sequence would be highly conserved across all species. It turns out that the underlying centromeric DNA sequences between species ranging from the yeast, fly, mouse to humans are in fact highly diverged suggesting a DNA sequence independent or an epigenetic mechanism of centromere formation. / Neocentromeres are centromeres that form de-novo at genomic locations that are devoid of highly repetitive a-satellite DNA sequences of which normal centromeres are usually comprised from. To date, the 10q25 neocentromere is the most well-characterised, fully functional human centromere that has been used previously to characterise the extent of a number of centromeric protein binding domains and characterise the properties of the underlying DNA sequence. Along with other factors, the existence of neocentromeres has given rise to a hypothesis where centromeres are defined by epigenetic or DNA sequence independent mechanisms. / The putative 10q25 neocentromere domain was recently redefined by high resolution mapping of Centromeric protein A (CENP-A) binding through a chromatin immunoprecipitation and array (CIA) analysis. The underlying DNA sequence was investigated to determine and confirm that the formation of the 10q25 neocentromere was through an epigenetic mechanism. Through a high-density restriction fragment length polymorphism (RFLP) analysis using overlapping PCR amplified DNA derived from genomic DNA representing the 10q25 region before and after neocentromere activation. No sequence polymorphisms, large insertions or deletions were detected and confirmed the epigenetic hypothesis of centromere formation. / DNA methylation is one of many epigenetic factors that are important for cellular differentiation, gene regulation and genomic imprinting. As the mechanisms and functions of DNA methylation have been well characterised, its role at the 10q25 neocentromere was investigated to try and identify the candidate epigenetic mechanism involved in the formation of centromeres. DNA methylation across the neocentromere was assessed using sodium bisulfite PCR and sequencing of selected CpG islands located across the 10q25 neocentromere. Overall, the methylation level of the selected CpG islands demonstrated no difference in DNA methylation before and after neocentromere activation. However, significant hypomethylation upon neocentromere formation was detected close to the protein-binding domain boundaries mapped previously suggesting that this may have a role in demarcating protein binding domains at the neocentromere. / Further analysis of DNA methylation investigated non-CpG island methylation at sites defined as CpG islets and CpG orphans. Interestingly, the DNA methylation level measured at selected CpG islets and CpG orphans across the 10q25 neocentromere were not completely hypermethylated as previously thought, but demonstrated variable methylation that became fully hypermethylated upon neocentromere activation in most sites investigated. These results suggested that a role for DNA methylation existed at the 10q25 neocentromere and that it occurred at sites devoid of CpG islands. / This study has found that DNA methylation at non-CpG island sites was variable contrary to popular belief and, was linked with neocentromere formation through the observation of increased DNA methylation at the 10q25 neocentromere. Inhibition of DNA methylation demonstrated increased neocentromere instability and a decrease in methylation of these CpG islets and CpG orphans confirming the importance of DNA methylation at neocentromeres. This study has characterised a new class of sequences that are involved in the maintenance of chromatin structure through DNA methylation at the 10q25 neocentromere.

DNA vaccines offer unique promise as a means of generating immunity against infectious and malignant disease. Unfortunately a number of obstacles, including rapid degradation of naked plasmid DNA (pDNA), poor cellular uptake by antigen presenting cells (APCs) and subsequent low levels of gene expression have limited the ability of DNA vaccines to raise sufficient immune responses towards the target antigen. This thesis is focused on investigating the immunostimulatory potential of liposomal nanoparticulate (LN) formulations of pDNA (stabilized plasmid lipid particles; SPLP) and cytosine-guanine oligodeoxynucleotides (CpG-ODN; LN CpG-ODN), and examining their ability to act together as a non-viral DNA vaccine in attempt to address the shortcomings of current DNA vaccine approaches. One focus of this thesis concerns investigating the immunostimulatory activity of LN formulations of CpG-ODN and pDNA. It is shown that despite dramatic differences in pharmacokinetics and biodistribution of LN CpG-ODN following intravenous (i.v.) and subcutaneous (s.c.) administration the resultant immune response is very similar, which is concluded to be due to the intrinsic ability of APCs to sequester LN CpG- ODN. In addition, it is demonstrated that lipid encapsulation dramatically enhances the immunostimulatory potential of pDNA and it is observed that SPLP maintains immunostimulatory activity in Toll-like receptor 9 (TLR9) knock-out mice. Together theses findings highlight the need for DNA-based therapies to consider both TLR9-dependent and -independent immunostimulatory activities of pDNA when constructing non-viral vectors. Furthermore, a new role for SPLP as a non-viral gene delivery vehicle for the generation of a systemically administered genetic vaccine in the presence of LN CpG-ODN is introduced. The ability of vaccination with SPLP to act prophylactically, to protect mice from tumour challenge, and therapeutically, in a novel vaccination strategy where the antigen is expressed at the tumour site as a result of SPLP-mediated transfection, is explored, demonstrating that in the presence of LN CpG-ODN SPLP possesses potential as a non-viral delivery system for DNA-based cancer vaccines. In summary, this work represents a substantial advance in the understanding of the immunostimulatory potential of both SPLP and LN CpG-ODN and provides insight into their ability to work together as a non-viral DNA vaccine.

Vaccination is one of the major achievements of modern medicine. As a result of vaccination, diseases such as polio and measles have been controlled and small pox has been eliminated. However, despite these successes there are still many diseases of microbial origin that cause tremendous suffering because there are no vaccines or the vaccines available are inadequate. The development of DNA based vaccines and immunostimulatory CpG oligonucleotides (ODNs) as adjuvants offer new possibilities for developing new vaccines. The objectives of this research were to improve the delivery of polynucleotides and oligonucleotides to enhance their potency and to evaluate the feasibility of non-invasive methods for the delivery of vaccines through the skin in order to improve the safety and the ease of administration of human and veterinary vaccines. The results demonstrated that topical administration of plasmids in a lipid-based delivery system (biphasic lipid vesicles [Biphasix]) resulted in gene expression in the draining lymph nodes, as well as induction of antigen specific immune responses in mice. The use of electroporation significantly enhanced both gene expression and immune responses to DNA vaccines in pigs. Prior treatment with electroporation enhanced immune responses to both protein and DNA vaccines indicating that both gene expression and tissue damage are important mechanisms that electroporation uses to enhance immune responses. In addition, the formulation of CpG ODNs in biphasic lipid vesicles (BiphasixTM) called Vaccine-Targeting Adjuvant (VTA) enhanced immune response to protein antigens following systemic and mucosal administration.

As phosphorylation represents the pivotal mechanism for regulation of biological processes, kinases belong to one of the most biologically significant enzyme classes. The development of analytical techniques for characterization of kinase activity, in particular at a global scale, is a central priority for proteomic and cell biology researchers. In order to facilitate global analysis of cellular phosphorylation, a new paradigm of microarray technology which focuses on analysis of total cellular kinase activity, kinome, has emerged in the past few years. As the specificity of many kinases is dictated primarily by recognition of residues immediately surrounding the site of phosphorylation a logical methodology is to employ peptides representing these immediate sequences as experimental substrates. Microarray chips carrying hundreds of such substrate targets have been developed for human kinome analysis, however, lack of similar tools for species outside research mainstream has limited kinome analysis in these species.<p> Based on sequence alignment of orthologous phosphoproteins from mammalian species, conservation of amino acid identity is reported to be 80 %. Accordingly, the potential exists to utilize phosphorylation sequence databases to extrapolate phosphorylation sites in other species based on their genomic sequence information. Peptides representing these proposed phosphorylation sites can then be utilized as substrates to quantify the activity of the corresponding kinase. Based on these principles, a bovine microarray of 300 unique peptide targets was constructed. The bovine phosphorylation targets were selected to represent a spectrum of cellular events but with focus on processes related to innate immunity. Initial application and validation of the bovine peptide arrays was carried out for kinome analysis of bovine blood monocytes stimulated with either lipopolysaccharide (LPS) or CpG-ODNs; ligands for Toll-like receptors (TLR) 4 and 9, respectively. The arrays confirmed activation of the known TLR signaling pathway as well as identifying receptor-specific phosphorylation events. Phosphorylation events not previously attributed to TLR activation were also identified and validated by independent bioassays. This investigation offers insight into the complexity of TLR signaling and more importantly verifies the potential to use bioinformatics approaches to create tools for species-specific kinome analysis based on genomic information.

Vaccination is one of the major achievements of modern medicine. As a result of vaccination, diseases such as polio and measles have been controlled and small pox has been eliminated. However, despite these successes there are still many diseases of microbial origin that cause tremendous suffering because there are no vaccines or the vaccines available are inadequate. The development of DNA based vaccines and immunostimulatory CpG oligonucleotides (ODNs) as adjuvants offer new possibilities for developing new vaccines. The objectives of this research were to improve the delivery of polynucleotides and oligonucleotides to enhance their potency and to evaluate the feasibility of non-invasive methods for the delivery of vaccines through the skin in order to improve the safety and the ease of administration of human and veterinary vaccines. The results demonstrated that topical administration of plasmids in a lipid-based delivery system (biphasic lipid vesicles [Biphasix]) resulted in gene expression in the draining lymph nodes, as well as induction of antigen specific immune responses in mice. The use of electroporation significantly enhanced both gene expression and immune responses to DNA vaccines in pigs. Prior treatment with electroporation enhanced immune responses to both protein and DNA vaccines indicating that both gene expression and tissue damage are important mechanisms that electroporation uses to enhance immune responses. In addition, the formulation of CpG ODNs in biphasic lipid vesicles (BiphasixTM) called Vaccine-Targeting Adjuvant (VTA) enhanced immune response to protein antigens following systemic and mucosal administration.

As phosphorylation represents the pivotal mechanism for regulation of biological processes, kinases belong to one of the most biologically significant enzyme classes. The development of analytical techniques for characterization of kinase activity, in particular at a global scale, is a central priority for proteomic and cell biology researchers. In order to facilitate global analysis of cellular phosphorylation, a new paradigm of microarray technology which focuses on analysis of total cellular kinase activity, kinome, has emerged in the past few years. As the specificity of many kinases is dictated primarily by recognition of residues immediately surrounding the site of phosphorylation a logical methodology is to employ peptides representing these immediate sequences as experimental substrates. Microarray chips carrying hundreds of such substrate targets have been developed for human kinome analysis, however, lack of similar tools for species outside research mainstream has limited kinome analysis in these species.<p> Based on sequence alignment of orthologous phosphoproteins from mammalian species, conservation of amino acid identity is reported to be 80 %. Accordingly, the potential exists to utilize phosphorylation sequence databases to extrapolate phosphorylation sites in other species based on their genomic sequence information. Peptides representing these proposed phosphorylation sites can then be utilized as substrates to quantify the activity of the corresponding kinase. Based on these principles, a bovine microarray of 300 unique peptide targets was constructed. The bovine phosphorylation targets were selected to represent a spectrum of cellular events but with focus on processes related to innate immunity. Initial application and validation of the bovine peptide arrays was carried out for kinome analysis of bovine blood monocytes stimulated with either lipopolysaccharide (LPS) or CpG-ODNs; ligands for Toll-like receptors (TLR) 4 and 9, respectively. The arrays confirmed activation of the known TLR signaling pathway as well as identifying receptor-specific phosphorylation events. Phosphorylation events not previously attributed to TLR activation were also identified and validated by independent bioassays. This investigation offers insight into the complexity of TLR signaling and more importantly verifies the potential to use bioinformatics approaches to create tools for species-specific kinome analysis based on genomic information.

The purpose of this research was to investigate selected methods of mucosal immunization for commercial chickens. Induction of mucosal immunity in commercial chickens through the use of orally administered subunit vaccines or through immunomodulation of the host??s response to live vaccines may be a viable means to control enteric infections in commercial poultry. In the present investigations we evaluated a means for delivering protein antigen in the drinking water and the use of CpG-ODNs, a recently reported mucosal adjuvant, in order to both improve this response and to modulate the host??s immune response when vaccinated with field strains of Eimeria acervulina and Eimeria tenella. In order to evaluate the efficacy of immunizing commercial poultry with subunit vaccines through the drinking water we chose the model antigen Bovine Serum Albumin (BSA). Chicks were administered BSA via intraperitoneal (I.P.) injection, oral crop gavage, or orally through the addition of BSA to the drinking water. These experiments demonstrated the efficacy of drinking water administration to induce antibodyproduction in the serum, intestine, and bile. When BSA was co-administered with CpGODNs we observed a modest increase in this response dependent upon dose. To evaluate the immunomodulation of the host response to live parasite using CpG-ODNs we used three administration models. The first was a single dose of CpGODNs with a trickle immunization regime of Eimeria acervulina. The second was coadministration of CpG-ODNs with a clinical dose of Eimeria acervulina or tenella. The third was pre-administration of CpG-ODNs 24 hours prior to the clinical dose of either species. These studies demonstrate that the first and third models were effective in reducing lesions and improving performance.

DNA vaccines offer unique promise as a means of generating immunity against infectious and malignant disease. Unfortunately a number of obstacles, including rapid degradation of naked plasmid DNA (pDNA), poor cellular uptake by antigen presenting cells (APCs) and subsequent low levels of gene expression have limited the ability of DNA vaccines to raise sufficient immune responses towards the target antigen. This thesis is focused on investigating the immunostimulatory potential of liposomal nanoparticulate (LN) formulations of pDNA (stabilized plasmid lipid particles; SPLP) and cytosine-guanine oligodeoxynucleotides (CpG-ODN; LN CpG-ODN), and examining their ability to act together as a non-viral DNA vaccine in attempt to address the shortcomings of current DNA vaccine approaches. One focus of this thesis concerns investigating the immunostimulatory activity of LN formulations of CpG-ODN and pDNA. It is shown that despite dramatic differences in pharmacokinetics and biodistribution of LN CpG-ODN following intravenous (i.v.) and subcutaneous (s.c.) administration the resultant immune response is very similar, which is concluded to be due to the intrinsic ability of APCs to sequester LN CpG- ODN. In addition, it is demonstrated that lipid encapsulation dramatically enhances the immunostimulatory potential of pDNA and it is observed that SPLP maintains immunostimulatory activity in Toll-like receptor 9 (TLR9) knock-out mice. Together theses findings highlight the need for DNA-based therapies to consider both TLR9-dependent and -independent immunostimulatory activities of pDNA when constructing non-viral vectors. Furthermore, a new role for SPLP as a non-viral gene delivery vehicle for the generation of a systemically administered genetic vaccine in the presence of LN CpG-ODN is introduced. The ability of vaccination with SPLP to act prophylactically, to protect mice from tumour challenge, and therapeutically, in a novel vaccination strategy where the antigen is expressed at the tumour site as a result of SPLP-mediated transfection, is explored, demonstrating that in the presence of LN CpG-ODN SPLP possesses potential as a non-viral delivery system for DNA-based cancer vaccines. In summary, this work represents a substantial advance in the understanding of the immunostimulatory potential of both SPLP and LN CpG-ODN and provides insight into their ability to work together as a non-viral DNA vaccine.

The Centromere is a vital chromosomal structure that ensures faithful segregation of replicated chromosomes to their respective daughter cells. With such an important structure, one would expect the underlying centromeric DNA sequence would be highly conserved across all species. It turns out that the underlying centromeric DNA sequences between species ranging from the yeast, fly, mouse to humans are in fact highly diverged suggesting a DNA sequence independent or an epigenetic mechanism of centromere formation. / Neocentromeres are centromeres that form de-novo at genomic locations that are devoid of highly repetitive a-satellite DNA sequences of which normal centromeres are usually comprised from. To date, the 10q25 neocentromere is the most well-characterised, fully functional human centromere that has been used previously to characterise the extent of a number of centromeric protein binding domains and characterise the properties of the underlying DNA sequence. Along with other factors, the existence of neocentromeres has given rise to a hypothesis where centromeres are defined by epigenetic or DNA sequence independent mechanisms. / The putative 10q25 neocentromere domain was recently redefined by high resolution mapping of Centromeric protein A (CENP-A) binding through a chromatin immunoprecipitation and array (CIA) analysis. The underlying DNA sequence was investigated to determine and confirm that the formation of the 10q25 neocentromere was through an epigenetic mechanism. Through a high-density restriction fragment length polymorphism (RFLP) analysis using overlapping PCR amplified DNA derived from genomic DNA representing the 10q25 region before and after neocentromere activation. No sequence polymorphisms, large insertions or deletions were detected and confirmed the epigenetic hypothesis of centromere formation. / DNA methylation is one of many epigenetic factors that are important for cellular differentiation, gene regulation and genomic imprinting. As the mechanisms and functions of DNA methylation have been well characterised, its role at the 10q25 neocentromere was investigated to try and identify the candidate epigenetic mechanism involved in the formation of centromeres. DNA methylation across the neocentromere was assessed using sodium bisulfite PCR and sequencing of selected CpG islands located across the 10q25 neocentromere. Overall, the methylation level of the selected CpG islands demonstrated no difference in DNA methylation before and after neocentromere activation. However, significant hypomethylation upon neocentromere formation was detected close to the protein-binding domain boundaries mapped previously suggesting that this may have a role in demarcating protein binding domains at the neocentromere. / Further analysis of DNA methylation investigated non-CpG island methylation at sites defined as CpG islets and CpG orphans. Interestingly, the DNA methylation level measured at selected CpG islets and CpG orphans across the 10q25 neocentromere were not completely hypermethylated as previously thought, but demonstrated variable methylation that became fully hypermethylated upon neocentromere activation in most sites investigated. These results suggested that a role for DNA methylation existed at the 10q25 neocentromere and that it occurred at sites devoid of CpG islands. / This study has found that DNA methylation at non-CpG island sites was variable contrary to popular belief and, was linked with neocentromere formation through the observation of increased DNA methylation at the 10q25 neocentromere. Inhibition of DNA methylation demonstrated increased neocentromere instability and a decrease in methylation of these CpG islets and CpG orphans confirming the importance of DNA methylation at neocentromeres. This study has characterised a new class of sequences that are involved in the maintenance of chromatin structure through DNA methylation at the 10q25 neocentromere.