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Target Validation And Pharmacological Characterization Of Novel Nmdar Modulators, Kiran Sapkota

Theses & Dissertations

The N-methyl-D aspartate receptors (NMDARs) are ligand-gated ion channels, which play important roles in learning and memory. Excessive activity of NMDARs is implicated in damage due to stroke and neurodegenerative diseases, whereas hypoactivity of NMDARs contributes to schizophrenia. The initial goal of my dissertation is to evaluate the potential role of the GluN2D-containing NMDARs in neuropathological, behavioral and cognitive alterations associated with schizophrenia and characterize the pharmacology and mechanisms of action of NMDAR modulators which could potentially be used to modulate these receptors in schizophrenia.

A subanesthetic dose of the NMDAR antagonist ketamine elicits symptoms of schizophrenia. This property led …

Defining The Role Of Phosphorylation And Dephosphorylation In The Regulation Of Gap Junction Proteins, Hanjun Li

Theses & Dissertations

Gap junctions are intercellular channels that permit the free passage of ions, small metabolites, and signaling molecules between neighboring cells. In the diseased human heart, altered ventricular gap junction organization and connexin expression (i.e., remodeling) are key contributors to rhythm disturbances and contractile dysfunction. Connexin43 (Cx43) is the dominant gap junction protein isoform in the ventricle which is under tight regulation by serine/tyrosine phosphorylation. Phosphorylation and dephosphorylation regulate many aspects of Cx43 function including trafficking, assembly and disassembly, electrical and metabolic coupling at the plaque, as well as to modulate the interaction with other proteins.

Serine phosphorylation has long been …

Staphylococcus Aureus Biofilms Interfere With Macrophage Antimicrobial Responses Through Differential Gene Regulation, Toxin Production, And Purine Metabolism, Tyler D. Scherr

Theses & Dissertations

Staphylococcus aureus (S. aureus) is an opportunistic pathogen that is a leading cause of both nosocomial and community-associated infections. Armed with a myriad of virulence factors and the propensity to form a biofilm on native tissues and implanted medical devices alike, S. aureus infections represent a very real public health threat, the treatment of which results in an excessive economic burden. S. aureus biofilm infections are notoriously recalcitrant to antibiotic therapy and adept at evading and neutralizing the host immune antimicrobial response. Previous studies from our laboratory have shown that S. aureus biofilms are able to cause persistent …

Amino Acid Catabolism In Staphylococcus Aureus, Cortney Halsey

Theses & Dissertations

Staphylococcus aureus must rapidly adapt to a variety of carbon and nitrogen sources during invasion of a host. Within a staphylococcal abscess, preferred carbon sources such as glucose are limiting, suggesting S. aureus survives through the catabolism of secondary carbon sources. S. aureus encodes pathways to catabolize multiple amino acids including those that generate pyruvate, 2-oxoglutarate, and oxaloacetate. To assess amino acid catabolism, S. aureus JE2 and mutants were grown in complete defined medium containing 18 amino acids but lacking glucose (CDM). A mutation in glutamate dehydrogenase (gudB), which generates 2-oxoglutarate from glutamate, abrogated growth in CDM suggesting …

Global Gene Expression Profiling Of Healthy Human Brain And Its Application In Studying Neurological Disorders, Simarjeet K. Negi

Theses & Dissertations

The human brain is the most complex structure known to mankind and one of the greatest challenges in modern biology is to understand how it is built and organized. The power of the brain arises from its variety of cells and structures, and ultimately where and when different genes are switched on and off throughout the brain tissue. In other words, brain function depends on the precise regulation of gene expression in its sub-anatomical structures. But, our understanding of the complexity and dynamics of the transcriptome of the human brain is still incomplete. To fill in the need, we designed …

The Functions Of The Cid And Lrg Operons In S. Aureus Programmed Cell Death, Xinyan Zhang

Theses & Dissertations

Staphylococcus aureus cid/lrg operons regulate the formation of S.aureus biofilm formation and programmed cell death based on previous in vivo work done in Dr. Bayles's lab. cid operon, which encodes CidA/CidB/CidC proteins, has been shown to be an effector in leading to the lysis and death of the S.aureus; While lrg operon, encoding LrgA and LrgB proteins, is an inhibitor of the lysis and death. Recent studies suggest that CidA behaves like holin proteins from bacterial phage, by increasing the murein hydrolysis activity under aerobic culturing conditions. LrgA, together with LrgB, appears to inhibit this function. …

Regulation Of Alteration/Deficiency In Activation 3 (Ada3) By Acetylation And Its Role In Cell Cycle Regulation And Oncogenesis, Shashank Srivastava

Theses & Dissertations

The ADA3 (Alteration/Deficiency in Activation 3) protein is a transcriptional adaptor protein that was initially discovered as a component of several HAT (Histone Acetyltransferase) complexes, the enzyme complex responsible for histone acetylation, which is a prerequisite for transcription. Earlier the studies from Dr. Band’s laboratory and that of others’ have deciphered a crucial role of ADA3 in cell cycle regulation (both through G₁/S and G₂/M phase transitions) and in maintaining the genomic stability.

While our laboratory investigated the mechanism behind the role of ADA3 in G₁/S transition, the same remained unknown for G_{2 …}

Mitogen And Morphogen Signaling Dysregulation: Pathophysiological Influence In Pancreatic Cancer And Alzheimer’S Disease, Eric Cruz

Theses & Dissertations

Although the etiology of a particular disease will vary, there are genetic and epigenetic bottlenecks that frequently converge resulting in dysregulation of mitogenic and morphogenetic signaling. This propensity is acutely experienced in malignancy and neurodegenerative disease.

Here, we have first investigated the role of dysregulated signaling in the context of pancreatic cancer (PC). Morphogenetic signaling has been regarded as a pleiotropic pathway with the potential to promote and inhibit metastatic features. Our investigation of bone morphogenetic protein 2 (BMP-2), an archetypical member of the BMP superfamily, has revealed the presence of extracellular, intracellular, and long non-coding RNA products. Our findings …

Dna Polymerase Zeta-Dependent Mutagenesis: Molecular Specificity, Extent Of Error-Prone Synthesis, And The Role Of Dntp Pools, Olga V. Kochenova

Theses & Dissertations

Despite multiple DNA repair pathways, DNA lesions can escape repair and compromise normal chromosomal replication, leading to genome instability. Cells utilize specialized low-fidelity Translesion Synthesis (TLS) DNA polymerases to bypass lesions and rescue arrested replication forks. TLS is a highly conserved two-step process that involves insertion of a nucleotide opposite a lesion and extension of the resulting aberrant primer terminus. The first step can be performed by both replicative and TLS DNA polymerases and, because of non-instructive DNA lesions, often results in a nucleotide misincorporation. The second step is almost exclusively catalyzed by DNA polymerase ζ …

Role Of Cbl-Family Ubiquitin Ligases As Critical Negative Regulators Of T Cell Activation And Functions, Benjamin Goetz

Theses & Dissertations

Adaptive T cell immunity is essential for defense against foreign antigens and immune surveillance against cancer. Tight regulation of T cell activation is required to avoid autoimmunity to self-antigens or protracted inflammation after foreign antigens are cleared. Incomplete or inappropriate stimulation leads to an active shutdown of T cell activation called anergy. The Casitas B-lineage Lymphoma (CBL)-family of ubiquitin ligases (E3s) are essential negative regulators of T cell activation that impinge on thymic selection as well as anergy induction programs. Single gene studies show that CBL is critical during T cell development while CBL-B plays an essential role in peripheral …

Chimerscope: A Novel Alignment-Free Algorithm For Fusion Gene Prediction Using Paired-End Short Reads, You Li

Theses & Dissertations

Fusion genes are those that result from the fusion of two or more genes, and they are typically generated due to the perturbations in the genome structure in cancer cells. In turn, fusion genes can contribute to tumor formation and progression by promoting the expression of an oncogene, deregulation of a tumor-suppressor, or producing much more active abnormal proteins. More importantly, oncogenic fusion genes are specifically expressed in the tumor cells, which provide enormous diagnostic and therapeutic advantages for cancer treatment. With the development of next-generation sequencing (NGS) technology, RNA-Seq becomes increasingly popular for transcriptomic study because of its high …

Motor Control In Individuals With Multiple Sclerosis, David Arpin

Theses & Dissertations

This dissertation explored motor control in individuals with multiple sclerosis (MS) by quantifying the behavioral and neurophysiological deficits present in these individuals. We behaviorally quantified the precision of the ankle plantarflexor musculature of individuals with MS. Our results indicated that the individuals with MS had a greater amount of variability in the precision of the isometric ankle torques, and that this greater variability was related to decreased walking performance. To further explore whether these motor control deficits were due to aberrant cortical activity associated with planning motor actions, we used magnetoencephalography to assess the motor planning and execution stages of …

Preliminary Examination Of The Bacterial Diversity Harbored By The Pill Bug (Armadillidium Vulgare), Sondos Alhajouj

Theses & Dissertations

Pill bugs (Armadillidium vulgare) were examined at 4 time points during 2015- 2016. The time points corresponded to summer, fall, winter, and spring. At each time point, 2 to 10 pill bugs were collected from each of three sites. All sites were located in San Antonio, Texas. The first site was in central San Antonio, but due to difficulties in collecting specimens the first site was only utilized at the first time point. The remaining localities, Bonilla Science Hall on the campus of the University of the Incarnate Word and a private residence in northwest San Antonio, were …

The Effect Of Varying Environmental Conditions On The Growth Of Stenotrophomonas Maltophilia, Norah Alqahtani

Theses & Dissertations

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen in the debilitated host. It possesses the ability to target and colonize respiratory-tract epithelial cells and grow on the surface of medical devices. It is associated with a significant case-fatality ratio in cystic fibrosis patients. S. maltophilia species have the ability to grow in bacterial biofilms, which further complicates these infections by providing the opportunity for acquisition of antibiotic resistant genes. This study investigated the effects on the growth of different strains of the same species of S. maltophilia, ATCC 51331 and 13637, when the selected environmental factors are varied. …

Role Of Ddr1 In Pancreatic Cancer, Huocong Huang

Theses & Dissertations

Pancreatic ductal adenocarcinomas are highly malignant cancers, characterized by extensive invasion into surrounding tissues, metastasis to distant organs at a very early stage, and a limited response to therapy. One of the main features of pancreatic ductal adenocarcinomas is desmoplasia, which leads to extensive deposition of collagen I. We have demonstrated that collagen I can induce epithelial-mesenchymal transition (EMT) in pancreatic cancer cells. A hallmark of EMT is an increase in the expression of a mesenchymal cadherin, N-cadherin. Our previous studies have shown that up-regulation of N-cadherin can promote tumor cell invasion and that collagen I-induced EMT is through two …

Exploration Into The Functional Impact Of Muc1 On The Formation And Regulation Of Transcriptional Complexes Containing Ap-1 And P53, Ryan L. Hanson

Theses & Dissertations

The transmembrane glycoprotein MUC1 is aberrantly expressed in the majority of pancreatic ductal adenocarcinoma cases and promotes tumor progression by engaging in morphogenetic signaling through its cytoplasmic tail. Furthermore, MUC1 can translocate to the nucleus and function as a transcriptional co-regulator in conjunction with transcriptional complexes containing activator protein-1 (AP-1) and p53. The specificity of these interactions are thought to rely on specific patterning of post-translational modifications within the cytoplasmic tail of MUC1.

Within this dissertation, we examined how MUC1 influences the formation and activity of these transcription factors and the resulting impact on tumor progression and metastasis. In our …

Study Of The Structure-Related Functions Of Eukaryotic Primase-Pol Alpha Complex During Replication, Yinbo Zhang

Theses & Dissertations

During eukaryotic replication primase•polymerase α (prim•polα) complex synthesizes de novo chimeric primers composed of about 10 nt RNA and 20 nt DNA, which are subsequently extended by main replicative DNA polymerases (pol), polε and polδ, on leading and lagging strands, respectively. It is estimated that prim•polα initiates more than 10 millions of lagging strand Okazaki fragments in human genome in each replication cycle. A concerted action of the two active sites, RNA pol and DNA pol, is required to ensure the efficient priming. A remarkable feature of the prim•polα complex is the “programmed” synthesis of the chimeric primer, where the …

Mutations Affecting Epigenetic Regulators And Their Role In Peripheral T-Cell Lymphomas, Chao Wang

Theses & Dissertations

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of generally aggressive lymphoid malignancies, accounting for 10-15% of all non-Hodgkin lymphomas. Angioimmunoblastic T-cell lymphoma (AITL) represents approximately 20% of all PTCLs and is recognized as a distinct entity. Accurate diagnosis and classification of PTCL remain challenging. With the exception of ALK+ ALCL, patients with PTCL generally have a poor prognosis with standard chemotherapy and even with the availability of many novel drugs, including HDAC inhibitor (romidepsin and belinostat), gemcitabine, and bortezomib. Therefore, deciphering the pathogenesis of this group of diseases is needed to identify novel treatable targets for better therapeutic intervention. …

Molecular Mechanisms Involved In Neurotoxicity Mediated By Hiv Proteins And Drug Abuse, Yu Cai

Theses & Dissertations

While the advancement of highly active antiretroviral therapy (HAART) has transformed the course of HIV/AIDS from a death sentence to a manageable chronic condition, the prevalence of a constellation of neurological disorders collectively termed as HIV-associated neurocognitive disorders (HAND) continues to persist in these patients. HAND is characterized by cognitive dysfunction, depression, impaired memory and/or deficits in motor skills. The underlying factors leading to HAND have been the subject of extensive research and are thought to be associated with HIV infection in the CNS combined with robust immune activation of resident cells of the CNS. In addition, there is a …

Voltage-Gated K+ Channels And Hiv-1-Induced Neural Injury: Implications For Pathogenesis Of Hiv-1-Associated Neurocognitive Disorders, Han Liu

Theses & Dissertations

Human immunodeficiency virus-1 (HIV-1)-associated neurocognitive disorder (HAND) is a subcortical disease involving neuronal loss and myelin damage. Myelin is deposited by oligodendrocytes through a complex process including oligodendrocyte progenitor cell (OPC) proliferation and maturation. Oligodendrocytes/OPCs are susceptible to viral proteins such as Tat and that myelin damage is associated with oligodendrocyte number decrease. It has been shown that activation of voltage-gated K⁺ (K_V) channels mediates apoptosis in various cell types. K_V1.3 is the most predominant K_V channel expressed in OPCs/oligodendrocytes and potentially involved in OPC developmental regulation. We studied the involvement of K_{V …}

The Mechanism Of Tubular Recycling Endosome Biogenesis, Shuwei Xie

Theses & Dissertations

Endocytic trafficking is a critical process for cellular homeostasis, and multiple ailments that include cardiovascular disease and cancer are related to the dysregulation of endocytic transport. As vesicles and target membranes are key to endocytic transport, lipids are essential for the regulation of endocytic trafficking pathways. We have shown that the tubular recycling endosomes (TRE) are essential for the regulation of endocytic recycling pathways. However, the mechanisms by which TRE are biosynthesized and carry out their functions remain unsolved. Studies from our lab have shown that phosphatidic acid (PA) recruits Molecule Interacting with Casl-Like protein 1 (MICAL-L1) as well as …

Genetic Landscape Of Pediatric Myelodysplastic Syndromes, Jennifer E. Grove

Theses & Dissertations

Myelodysplastic syndromes (MDS) are acquired heterogeneous hematopoietic clonal disorders primarily seen in the adult and elderly populations that presents a variety of cellular morphologies in cell lineages, varying prognoses, and differences in overall survival (OS) between individual patients. The occurrence of MDS in the pediatric and young adult population, or those between the ages of 0 and 29, is slowly on the rise. Pediatric and elderly cases exhibit diverse cytogenetic findings with differences in OS. The characterization of the genetic landscape of pediatric MDS is limited and most studies detailing genetic changes have been conducted in adult MDS cases. In …

Inflammation- And Cancer-Associated Neurolymphatic Remodeling And Cachexia In Pancreatic Ductal Adenocarcinoma, Darci M. Fink

Theses & Dissertations

This work addresses two understudied elements of inflammation and malignancy—namely, (1) neurolymphatic remodeling during transitions in microenvironmental inflammatory status and (2) the systemic paraneoplastic inflammatory syndrome cancer-associated cachexia in the context of pancreatic adenocarcinoma (PDAC). Lymphatic vessels undergo dramatic phenotypic changes in initial inflammation, wound recovery, and recurrent inflammation. We identified complementary novel neuroremodeling behaviors under these conditions and hypothesized that both nerve and lymphatic remodeling were directed by a tissue remodeling factor with overlapping functions. We found that nerve growth factor (NGF) influenced not only nerves but also lymphatics. NGF stimulated lymphangiogenesis, inhibited lymphatic vessel regression during wound recovery, …

The Role Of Dna Methyltransferases In Normal And Malignant Hematopoiesis, Staci Haney

Theses & Dissertations

DNA methylation is an epigenetic modification that regulates gene transcription. The addition of a methyl group to cytosine is catalyzed by a family of enzymes known as DNA methyltransferases (Dnmts). The three catalytically active Dnmts in humans and mice are Dnmt1, Dnmt3a, and Dnmt3b. DNA methylation is clinically relevant, as aberrations in the methylation landscape are a hallmark of nearly all human cancers. Cancer methylomes are typically characterized by genome wide hypomethylation and regional specific hypermethylation, both of which have been linked to alterations in gene expression. In order to understand the contribution of epimutations to the development of hematological …

Mobility Of Individuals With Multiple Sclerosis And The Influence Of Physical Therapy, Brenda L. Davies

Theses & Dissertations

One main purpose was to explore the compensatory gait strategies of individuals with multiple sclerosis (MS). To address this purpose, we quantified the mechanical work generated by the lower extremity joints during walking. The outcomes from this investi­gation suggested that individuals with MS redistribute positive mechanical work during walking to the hip in order to compensate for a reduced ability of the ankle to generate positive mechanical work. Additionally, we also explored the motor control of the ankle as a potential contributing factor to the mobility limitations of individuals with MS. The outcomes from this investigation indicated that individuals with …

The Role Of Ada3 Overexpression In Proliferation Through Enhancing Myc Expression, Nicolas I. Griffin

Theses & Dissertations

Breast cancer is a heterogeneous disease that is the second leading cause of cancer related deaths in women. Cancer is defined as abnormally heightened proliferation. In order for gene transcription and eventual translation to occur to drive the cell cycle to generate more cells, DNA must be uncoiled from nucleosomes by histone acetylation complexes. One of the key evolutionarily conserved components of these HAT complexes is alteration/deficiency in activation 3 (ADA3). In addition to the role in histone acetylation, this protein also functions as a coactivator for nuclear hormone receptors. Recent findings indicated that nuclear Ada3 correlates with ER+ breast …

Restriction Enzyme Generated Next-Generation Sequencing Libraries And Genetic Risk Modifiers Of Brca1 Mutation Carriers, Bradley Downs

Theses & Dissertations

Next-generation sequencing (NGS) is a high throughput technique used to sequence large amounts of DNA in a short amount of time. However, a limitation to NGS is that the generated data is in a single consensus sequence without distinguishing between variants on homologous chromosomes. Separating or phasing the variants from the maternal and paternal chromosomes can provide information about the genetic origin of disease and information about how DNA nucleotide alterations interact in cis. This dissertation explores a new technical method of using restriction enzymes during NGS library preparation and its ability to increase the amount of phasing information that …

Role Of Stemloop D In Terminally Deleted Coxsackievirus B3 Replication, Lee K. Jaramillo

Theses & Dissertations

Coxsackievirus B3 (CVB3) is an enterovirus with no known form of latency. However, assays designed to detect enteroviral RNA have shown that CVB3 RNA can persist for weeks beyond the acute infection both naturally and experimentally. Our previous work with coxsackievirus revealed an inhibited version of enteroviral replication where the progeny virus, termed terminally deleted (TD) virus, was missing a maximum of 49 nucleotides from the beginning of the 5’ non-translated region (NTR). The largest terminally deleted virus, TD50, effaced stem a, stemloop b, and stemloop c from the secondary structure, the cloverleaf. We hypothesized that further deletion beyond those …

Novel Regulatory Mechanisms And Functions Of Muc4 In Pancreatic Cancer, Suhasini Joshi

Theses & Dissertations

Mucins are high molecular weight glycoproteins and have critical functions in protecting epithelial cells from a myriad of cellular stress. However, mucins are expressed aberrantly under cancer conditions that allow tumors to progress and metastasize. Among many mucins, Mucin 4 (MUC4) serves as one of the top-differentially expressed proteins in pancreatic cancer (PC), however, the precise mechanism responsible for its aberrant expression is still not clear. The evolving view of cancer as an energetic and growing ecosystem underlines an intricate interplay between cancer and its microenvironment. In spite of being recognized as one of the most critical oncogenic proteins in …

The Role Of Oncogenic Kras In Initiation, Progression And Maintenance Of Pancreatic Cancer, Nirakar Rajbhandari

Theses & Dissertations

Pancreatic cancer is a lethal disease that is almost invariably associated with a KRAS gene mutation. Due to a very high frequency of gain-of-function mutations within the KRAS gene, and its proven role in initiation of pancreatic cancer in animal models, mutant KRAS is considered a rational therapeutic target. To determine the potential role of oncogenic KRAS in pancreatic tumor maintenance in vivo, we generated a mouse model with a Doxycycline regulated expression of oncogenic KRAS (KRAS^G12D) in pancreas. Using this reversible model, we demonstrated that the expression of oncogenic KRAS in a Cdkn2a deficient background was …