In Vivo Multi-Modal Imaging Approaches For Cancer, Stem And Immune Cells, Nourhan Shalaby

Electronic Thesis and Dissertation Repository

Introduction: Molecular imaging allows for non-invasive longitudinal visualization of cellular functions in vivo. This area of research has provided better understanding of fundamental molecular and biochemical processes, enabled optimization of pre-clinical and clinical assessments for new treatments, and allowed for more accurate and early detection of many pathologies. Extensive research for novel imaging techniques and emerging technologies have rapidly advanced the field. However, an ideal single imaging modality or approach does not exist. Alternatively, multi-modal imaging approaches are commonly applied to overcome limitations of individual technologies. In this thesis, we design, develop, validate, and image various cell types using …

Creating Tools To Study The Signaling And Function Of The Adhesion Family Of Gpcrs, Victor M. Mirka

Electronic Thesis and Dissertation Repository

Adhesion GPCRs (aGPCRs) are difficult to study because they are activated by mechanical force. aGPCRs are autoproteolytically cleaved into N-terminal and C-terminal fragments. Mechanical force removes the N-terminal fragment revealing a tethered ligand activating the receptor. Proteinase Activated Receptors (PARs) are N-terminally cleaved by proteinases revealing a tethered ligand activating the receptor. We hypothesized the tethered ligand of aGPCRs could be revealed by replacing the N-terminal fragment with a PAR N-terminus. We fused the PAR2 N-terminus to the C-terminal fragments of four aGPCRs: CD97, EMR2, GPR56, and BAI1. PAR2-aGPCR chimeric receptors dose dependently recruited G-proteins and β-arrestins, supporting our hypothesis. …

Protein Misfolding Toxicity And Inclusion Formation In Cellular Models Of Neurodegeneration, Sonja E. Di Gregorio

Electronic Thesis and Dissertation Repository

Protein misfolding characterizes most neurodegenerative diseases. Protein misfolding is the conversion of specific proteins from their normal, often soluble, and native three-dimensional conformation into an aberrant, often insoluble, non-functional conformation. Protein inclusions and aggregates are among the major pathological hallmarks of protein misfolding associated with many neurodegenerative diseases. Yet, the role of aggregates and inclusions is not clearly defined and heavily debated. This study utilizes powerful genetic approaches in yeast and verification in mammalian neuronal cell lines to address the misfolding and toxicity of three proteins, the Rho Guanine Nucleotide Exchange Factor (RGNEF), Matrin3, which are involved in amyotrophic lateral …

Hiv-1 Drug Resistance To Integrase Strand Transfer Inhibitors In Hiv-1 Non-B Subtypes, Emmanuel Ndashimye

Electronic Thesis and Dissertation Repository

Human immunodeficiency syndrome (HIV-1) has infected over 75 million people and over 35 million have succumbed to virus related illnesses. Despite access to a variety of antiretroviral therapy (ART) options, ART programs have been disproportionally spread in the world with low-and middle-income countries (LMICs) facing challenges to access the most potent ART options. With less potent ART remaining in use in LMICs, HIV-1 drug resistance (HIVDR) presents a growing challenge in LMICs. Since approval of the first-generation integrase strand transfer inhibitor (INSTIs), Raltegravir (RAL) in 2007, INSTIs remain the best choice as a backbone of ART. Access to second generation …

Trna Regulation In Humans: The Cellular Effect Of A Pathological Hars Y454s Mutation, Rosan Kenana

Electronic Thesis and Dissertation Repository

tRNAs are the adapter molecules involved in translating the genetic code into functional protein in a living cell. tRNAs are charged with their cognate amino acids - by aminoacyl-tRNA synthetases (aaRS or ARS) - which are then transferred to a growing peptide in a process called mRNA translation. The efficiency of translation is dependent on the ratio of ARS enzymes to their cognate tRNAs and the availability of correctly amino acylated tRNAs. Disruptions of this process, caused by mutations in ARS genes, in particular, have been linked to complex inherited diseases. USH3B syndrome, a recessively inherited disorder among consanguineous families …

Implications Of Long Non-Coding Rnas In The Pathogenesis Of Diabetic Retinopathy: A Novel Epigenetic Paradigm., Saumik Biswas

Electronic Thesis and Dissertation Repository

With the rising incidence of diabetic retinopathy (DR), there is an urgent need for novel therapies. Presently, several altered metabolic pathways have been implicated in the pathogenesis of DR. Recent advances in genomic technologies have identified considerable epigenetic alterations that also contribute to DR progression. Long non-coding RNAs (lncRNAs; >200 nucleotides), critical regulators of gene expression, are aberrantly expressed in DR and have not been comprehensively characterized. Our microarray analyses using human retinal endothelial cells (HRECs) revealed thousands of differentially expressed lncRNAs following high glucose (HG) exposure, with profound increases in the lncRNAs MALAT1 and HOTAIR. Using multiple techniques, …

Virally Packaged Rna In Virus-Like Particle Vaccines Enhances Antigenicity And Augments Latency Reversal Of Hiv-1, Chanuka Wijewardhana

Electronic Thesis and Dissertation Repository

Introduction:

Since Human Immunodeficiency Virus (HIV)-1 was determined to be the etiological agent behind acquired immunodeficiency syndrome (AIDS) in 1983, numerous attempts at a cure have been made; however, none have been effective. One of the primary roadblocks in achieving a cure is a transcriptionally-silent latent reservoir of memory CD4+ T cells harboring HIV provirus. Combined antiretroviral therapy (cART) inhibits actively replicating virus by interfering with various stages of the replication cycle. Therefore, non-replicative viruses–like the proviruses found in latently infected cells–are hidden from the actions of continued antiretroviral therapy. As a result, cART discontinuation or treatment holidays can result …

The Role Of The Tau N-Terminal Phosphatase-Activating Domain And Phosphorylation At Thr175 In The Formation Of Tau Cytoplasmic Inclusions, Matthew A. Hintermayer

Electronic Thesis and Dissertation Repository

Cytoplasmic inclusions and fibrils of the microtubule-associated protein tau (tau protein) are a key neuropathological hallmark in tauopathies, including Alzheimer’s disease, chronic traumatic encephalopathy, and amyotrophic lateral sclerosis with cognitive impairment. Previous research has demonstrated that the phosphorylation of tau protein at Thr¹⁷⁵ is sufficient for the initiation of fibril formation both in vitro and in vivo. Here we use mutated tau protein constructs to demonstrate that phosphorylation at Thr¹⁷⁵ results in the aberrant exposure of an N-terminal phosphatase-activating domain (PAD). The tau PAD interacts with protein phosphatase 1 (PP1) leading to the activation of glycogen synthase …

Modulation Of Inflammation Driven Wound Healing After Glaucoma Surgery, James J. Armstrong

Electronic Thesis and Dissertation Repository

Dysregulated wound healing contributes to most currently unanswered ophthalmological morbidity. Opacification and structure altering contractures compromise the delicate ocular anatomy upon which ocular function and healthy vision are reliant. Glaucoma filtration surgery, corneal stromal injury, proliferative vitreoretinopathy and age-related macular degeneration are major contributors to ocular morbidity – all with myofibroblast transdifferentiation and pathognomonic scarring activity at their core.

This thesis aims to revaluate the means by which dysregulated ocular wound healing is combated with evidence describing a novel strategy to mitigate its effects. A translational approach was used. An initial retrospective analysis of over ten thousand glaucoma surgeries found …

Improving The Genetic Diagnosis Of Familial Hypercholesterolemia, Michael Iacocca

Electronic Thesis and Dissertation Repository

Familial hypercholesterolemia (FH) is a genetic disorder of severely elevated low-density lipoprotein (LDL) cholesterol that is widely underdiagnosed and undertreated. To improve the identification of FH and initiate timely and appropriate treatment strategies, genetic testing is becoming increasingly offered worldwide as a central part of diagnosis. I describe three main ways providing a genetic diagnosis in FH can be improved. First, next-generation sequencing (NGS)-based approaches can be used to reliably identify large-scale variant types known as copy number variations (CNVs) in the LDL receptor gene (LDLR); second, NGS methodology can be further applied to extend CNV screening to …

Metabolic And Expression Changes Associated With A Mouse Model Of Intrauterine Growth Restriction (Iugr), Bethany N. Radford

Electronic Thesis and Dissertation Repository

Intrauterine growth restriction (IUGR) is a pregnancy condition where fetal growth is suboptimal, resulting in an infant born small for gestational age (<10th percentile) and is associated with metabolic disorders such as type 2 diabetes in adulthood. This study aims to understand tissue-specific adaptations to fetal undernutrition which predispose the individual to metabolic disorders in adulthood. A model of growth restriction in mice was established using 70% of maternal ad libitum total food (g) (E6.5-birth). At weaning, male offspring received standard chow or a HFHS diet. Body weight and random blood glucose levels were measured at 6 months. To assess metabolism at 6 or 7 months, glucose tolerance, pyruvate challenge and hepatic portal vein insulin challenge tests were administered and serum peptide markers for obesity and diabetes were measured. Metabolic cages were also used at 2 and 7 months to measure activity, food intake and respiratory exchange ratios (RERs). Adult liver, adipose and skeletal muscle and fetal liver was collected for RNA sequencing. Maternal nutrient restricted (MNR) offspring were growth restricted with disproportionately smaller fetal livers. 19% of standard chow-fed MNR offspring became glucose intolerant. On an isocaloric high-fat high-sugar diet no differences in MNR growth or glucose metabolism were detected. However, RERs were reduced at all timepoints in MNR on a HFHS relative to MNR on standard chow. Differences in transcription of genes involved in hypoxia signalling were detected and HIF-2a and HIF-3a proteins were increased in fetal liver of MNR offspring. Genes differentially expressed in the fetus were not differentially expressed at 6 months. Gene expression of metabolically regulatory transcripts in liver, adipose and skeletal muscle did not differ in all MNR and glucose intolerant MNR relative to controls. This model results in a susceptible and non-susceptible population of maternal nutrient restricted offspring and supports the concept of hypoxia signalling contributing to fetal adaptations. Understanding adaptations in hepatic hypoxia signalling in response to fetal undernutrition and how they vary in susceptible and unsusceptible populations will provide insight into how fetal nutrition can influence adult metabolism.

Coevolving Residues And The Expansion Of Substrate Permissibility In Laglidadg Homing Endonucleases, Thomas A. Mcmurrough

Electronic Thesis and Dissertation Repository

Genome-editing (GE) is a form of genetic engineering that permits the deliberate manipulation of genetic material for the study of biological processes, agricultural and industrial biotechnologies, and developing targeted therapies to cure human disease. While the potential application of GE is wide-ranging, the efficacy of most strategies is dependent upon the ability to accurately introduce a double-stranded break at the genomic location where alterations are desired. LAGLIDADG homing endonucleases (LHEs) are a class of mobile genetic element that recognize and cleave 22-bp sequences of DNA. Given this high degree of specificity, LHEs are powerful GE reagents, …

Mechanisms Regulating Stem Cell Phenotype In Infantile Hemangioma, Niamh Richmond

Electronic Thesis and Dissertation Repository

Infantile hemangiomas (IHs) are benign vascular neoplasms characterized by the differentiation of multipotential stem cells (hemSCs) into endothelial cells during the early proliferative phase, and later into adipocytes during spontaneous involution. Transforming growth factor-β (TGFβ) has been shown to be significantly elevated upon IH involution and this coincides with repression of a developmentally-regulated transcription factor T-box 2 (TBX2). These findings implicate both TGFβ and TBX2 in mediating hemSC differentiation during IH evolution. The aim of my study is to understand the role of TGFβ and TBX2 in hemSC differentiation. I performed immunofluorescence staining to localize TBX2 protein in sectioned IH …

Intracellular Trafficking Governs The Processing Of The Amyloid Precursor Protein And The Secretion Of Beta-Amyloid, Joshua Hoi Ki Tam

Electronic Thesis and Dissertation Repository

One of the hallmarks of Alzheimer’s disease (AD) is the pathological accumulation of β-amyloid (Aβ) in the brains of AD patients. Oligomeric and fibrillar aggregates of Aβ have been shown to be neurotoxic to neurons and hippocampal slices. Therefore, limiting Aβ production is an important area of research in order to delay or stop AD progression. Aβ is produced by amyloidogenic cleavage of amyloid precursor protein (APP). Amyloidogenic cleavage requires ectodomain removal by β-secretase and intramembrane γ-cleavage by γ-secretase to release Aβ products ranging from 38-43 residues. Work from our lab has shown that APP and γ-secretase are resident proteins …

Kidney Injury Molecule-1 Signalling In Ischemic Acute Kidney Injury And Phagocytosis, Ola Z. Ismail

Electronic Thesis and Dissertation Repository

Acute kidney injury (AKI) is defined by the rapid loss of kidney function due to tissue damage. It affects 10-30 % of hospitalized patients and is independently associated with increased morbidity and mortality. Ischemia-reperfusion injury (IRI) is the most common pathoetiological mechanism of AKI, whereby tissue injury is mediated by reactive oxygen species. Ischemic AKI leads to the rapid upregulation of a transmembrane protein, kidney injury molecule-1 (KIM-1) on the apical membrane of proximal tubular epithelial cells (TECs). Previous work from our group and others demonstrated that the extracellular domain of KIM-1 specifically binds to phosphatidylserine on apoptotic cells, thereby …

Characterization Of The Nicotine-Induced Endoplasmic Reticulum Stress Response In The Rat Placenta In Vivo And In Vitro, Michael Ka Chun Wong

Electronic Thesis and Dissertation Repository

Nicotine exposure during pregnancy leads to adverse health outcomes, including compromised placental development. Although the molecular mechanisms remain elusive, recent studies identified that endoplasmic reticulum (ER) stress may underlie poor placentation. Therefore, we were interested in investigating the effects of nicotine exposure on the ER stress response in the placenta. A well-established maternal nicotine exposure rat model and Rcho-1 trophoblast giant cell model were utilized to address the research questions. Maternal nicotine exposure in vivo led to elevated ER stress in association with impaired disulfide bond formation and hypoxia. Nicotine exposure in vitro further differentiated that ER stress may be …

Regulation Of Crfr1 And 5-Ht2ar By Pdz Domain-Containing Proteins Sap97 And Psd-95, Henry A. Dunn

Electronic Thesis and Dissertation Repository

Previous studies identified a crosstalk mechanism whereby CRFR1 sensitized 5-HT_2AR-mediated signaling via interactions with PDZ domain-containing proteins: a mechanism that may underlie stress-induced anxiety and depression. This prompted an investigation into uncovering which PDZ domain-containing proteins could regulate the crosstalk between these two receptors, and how they could be regulated individually. In the current studies, a subset of PDZ domain-containing proteins were identified that may interact with CRFR1 and 5-HT_2AR. The focus narrowed to two candidates previously implicated in psychiatric disease: SAP97 and PSD-95. We confirmed SAP97 and PSD-95 as interacting partners of CRFR1 in adult …

Regulation Of The High-Affinity Choline Transporter Activity And Trafficking In Alzheimer’S Disease-Related Pathological Conditions, Leah K. Cuddy

Electronic Thesis and Dissertation Repository

Cholinergic neurons play a key role in cognitive processes through the action of the neurotransmitter acetylcholine (ACh). Dysfunction of these neurons occurs in several neurodegenerative disorders, including Alzheimer’s disease (AD). The high-affinity choline transporter CHT recycles choline back into synaptic terminals, which is the rate-limiting step to ACh production. CHT proteins traffic between the cell surface and subcellular organelles in a constitutive manner, which maintains plasma membrane transporter levels, thereby regulating CHT activity and maintaining cholinergic transmission. Pathological conditions associated with AD may alter CHT function in a manner that reduces choline uptake activity and impairs cholinergic neurotransmission. Thus, my …

Genomic Predictors Of Drug Response To The Alpha-Specific Phosphoinositol 3-Kinase (Pi3ka-Alpha) Inhibitor Byl719 In Head And Neck Cancers, Giananthony T. Rizzo

Electronic Thesis and Dissertation Repository

PIK3CA is the only frequently mutated, druggable oncogene in head and neck squamous cell cancer (HNSCC), with PIK3CA point mutations and gene amplification rates of 17.5% and 40% respectively, with higher rates in HPV-positive disease. The objective of this research was to determine the effects of BYL719, an α-specific PI3K inhibitor in HNSCC cell lines.

All cell lines with PIK3CA hotspot point mutations or gene amplifications will be sensitive to BYL719.

Twenty-eight HNSCC cell lines were subjected to increasing concentrations of BYL719 and cell viability was measured over time. Cell lines were screened for activating PIK3CA hotspot mutations and amplifications …

Polycomb Repressive Complex 2 Regulates Mir-200b In Retinal Endothelial Cells: Possible Implications In Diabetic Retinopathy, Michael A. Ruiz

Electronic Thesis and Dissertation Repository

Glucose-induced augmented vascular endothelial growth factor (VEGF) production is a key event in diabetic retinopathy. We have previously demonstrated that downregulation of miR-200b increases VEGF, mediating structural and functional changes in the retina in diabetes. However, mechanisms regulating miR-200b in diabetes are not known. Histone methyltransferase complex, Polycomb Repressive Complex 2 (PRC2), has been shown to repress miRNAs in neoplastic process. We hypothesized that, in diabetes, PRC2 represses miR-200b through its histone H3 lysine-27 trimethylation mark. We show that human retinal microvascular endothelial cells exposed to high levels of glucose regulate miR-200b repression through histone methylation, and that inhibition of …

Mri Relaxation Rates: A Quantitative Approach To Track Tumour Cells Expressing Maga, Anindita Sengupta

Electronic Thesis and Dissertation Repository

Using magnetic resonance imaging, relaxation rate measurements were

performed in cancer cells overexpressing a magnetotactic bacterial gene, MagA.

Measurements of magnetic resonance relaxation rates in this expression

system is important for optimizing cell detection and specificity, for developing

quantification methods, and for refinement of gene-based iron contrast using

magnetosome associated genes. We measured the total transverse

relaxation rate (R2^*), its irreversible and reversible components (R2 and R2^′,

respectively) and the longitudinal relaxation rate (R1) in MDA-MB-435 tumor cells.

Clonal lines overexpressing MagA were cultured in the presence and absence of

iron supplementation, and mounted in a …

Systematic Assessment Of The Contribution Of Superantigens To Nasopharyngeal Colonization In A Mouse Model Of Streptococcal Infection, Katherine J. Kasper

Electronic Thesis and Dissertation Repository

Streptococcus pyogenes is adapted for persistence in humans. It typically colonizes the tonsils and skin, and humans are the only known reservoir. S. pyogenes can cause a wide range of mild to serious infections. Most streptococci-related deaths are due to complications of rheumatic fever and invasive infections. S. pyogenes produces virulence factors that contribute to the pathogen’s ability to colonize and cause disease, including streptococcal superantigens (SAgs), also known as streptococcal pyrogenic exotoxins (Spes). SAgs function by cross-linking T cells and antigen presenting cells (APC) which may cause a massive inflammatory response, and as such have been found to contribute …