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Amyloid Proteins Structure, Dynamics, Interactions And Early Stages Of Self-Assembly, Yuliang Zhang

Theses & Dissertations

The self-assembly and aggregation of amyloid protein are associated with several neurodegenerative diseases. The evidence indicates that the oligomeric intermediates, formed prior to the final fibrillary product, are the primary culprits of neurotoxicity. Although tremendous efforts have been dedicated for the characterization of structures, dynamics and toxic-related hallmarks of the oligomers, to date, yet the mechanism of such assembly from disordered monomers and their structure remain elusive.

In this dissertation, I focused on understanding the dimerization process of amyloid proteins and peptides of different sizes and I combined experimental studies with high-power computer simulations. The AFM force spectroscopy experiments showed …

Compensatory Mechanisms And T Cell Migration In Mouse Models Of Dopaminergic Loss, Kristi M. Anderson

Theses & Dissertations

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder and second most common neurodegenerative disorder. PD is characterized by the selective loss of dopaminergic neurons and dopamine neurotransmitter within the substantia nigra and termini in the striatum. Progressive loss of dopaminergic neurons occurs over many years in PD, and by the time movement disorder symptoms manifest, up to 50-70% of dopaminergic neurons have been lost. Several aspects of PD pathology have been described in detail, but a better understanding of PD progression is needed to develop more efficient treatments.

Motor symptoms associated with PD do not manifest until significant …

The Role Of Tumor Suppressor Co-Chaperone Chip/Stub1 In Erbb2-Mediated Oncogenesis, Haitao Luan

Theses & Dissertations

The epidermal growth factor receptor (EGFR) family member ErbB2 (Her2) is overexpressed in 20 -30% of invasive breast cancers and this overexpression correlates with poor prognosis and shorter overall as well as disease-free survival. Aberrant expression of ErbB2 through gene amplification, transcriptional deregulation and/or altered endocytic trafficking results in overexpression of ErbB2 at the plasma membrane and biases ErbB2 from primarily ligand-driven hetero-dimerization under normal expression conditions to increased ligand-independent homo-dimer and hetero-dimer formation and consequent activation. C-terminus of HSC70-Inteeracting protein (CHIP)/STIP1-homologous U-Box containing protein 1 (STUB1) is an HSP90/HSC70 interacting negative co-chaperone known to promote ubiquitination and degradation of …

Regulation Of The Transmembrane Mucin Muc4 By Wnt/Β-Catenin In Gastrointestinal Cancers, Priya Pai

Theses & Dissertations

The transmembrane mucin MUC4 is a high molecular weight glycoprotein that is expressed de novo in pancreatic ductal adenocarcinoma (PDAC). MUC4 has been shown to play a tumor-promoting role in malignancies such as PDAC, ovarian cancer and breast cancer. Unlike the normal pancreas, MUC4 is ordinarily expressed by goblet and absorptive cells in the normal colonic epithelium. However, its expression/role in colorectal cancer (CRC) is not well studied.

In this dissertation, the goal was to identify factor(s) that may differentially regulate MUC4 in these two disparate malignancies. Furthermore, in light of its pro-tumorigenic role in other malignancies, we analyzed the …

Acute Methamphetamine Exposure Affects Histone Modifying Enzymes And Cytokine Production In Macrophages, Ariel Burns

Theses & Dissertations

The effects of methamphetamine (Meth) in the periphery are not well studied and a comprehensive investigation on the effects and molecular mechanism will give insight into why Meth users are at an increased risk of infections. For this reason, we use macrophages as a model for the immune system dysregulation seen in Meth abusers and also because macrophages are a long-lived cell that HIV infects and persists in. We aimed to determine the effects of Meth on the cytokine production, histone modifying enzymes and the corresponding histone post-translational modifications, and the molecular mechanism in HIV-infected human macrophages treated with combination …

Development Of Manganese-Enhanced Magnetic Resonance Imaging (Memri) Methods To Study Pathophysiology Underlying Neurodegenerative Diseases In Murine Models, Aditya N. Bade

Theses & Dissertations

Manganese-enhanced magnetic resonance imaging (MEMRI) opens the great opportunity to study complex paradigms of central nervous system (CNS) in freely behaving animals and reveals new pathophysiological information that might be otherwise difficult to gain. Due to advantageous chemical and biological properties of manganese (Mn²⁺), MEMRI has been successfully applied in the studies of several neurological diseases using translational animal models to assess comprehensive information about neuronal activity, morphology, neuronal tracts, and rate of axonal transport. Although previous studies highlight the potential of MEMRI for brain imaging, the limitations concerning the use of Mn²⁺ in living animals and …

Epacs: Epigenetic Regulators That Affect Cell Survival In Cancer., Catherine Murari

Theses & Dissertations

Cyclic adenosine monophosphate (cAMP) is a second messenger responsive to many external stimuli, playing an important role in cellular gene expression, metabolism, migration, differentiation, hypertrophy, apoptosis and secretion. All of these cellular functions are important in many diseases including cancer. Most of its effects were initially attributed to the classical protein kinase A (PKA) protein, but cellular functions such as proliferation and migration were found to be PKA independent and dependent on the newly discovered exchange proteins directly activated by cAMP (EPACs). EPACs are single polypeptides that primarily function as guanine exchange factors (GEFs) for Rap proteins that allow the …

Control Of The Basal Recycling And Surface Expression Of Epidermal Growth Factor Receptor By The Endocytic Recycling Regulator Ehd1 Utilizing A Pathway Shared By Rusc2, Eric Tom

Theses & Dissertations

The epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase (RTK) and oncogene aberrantly expressed or mutated in solid tumors. Its surface expression is dynamically regulated. Display of an activation-competent pool is essential for response to ligands. Internalization and degradation of EGFR following stimulation has received the most attention, fewer studies have characterized the recycling arm of EGFR transit, basal traffic and surface display are poorly understood. Thus, we evaluated the endocytic recycling of EGFR for its therapeutic potential in EGFR driven cancers. The C-Terminal Eps15 homology (EH) domain-containing proteins have emerged as regulators of surface receptor recycling …

Interaction Between Angiotensin Ii And Bdnf In Modulating Sympathetic Nerve Activity, Bryan K. Becker

Theses & Dissertations

Over activation of the sympathetic nervous system is prevalent in many forms of cardiovascular disease such as chronic heart failure (CHF) and hypertension. Although increased neuronal renin-angiotensin system activity in presympathetic neurons has been well implicated in mediating this sympatho-excitation, many of the neuronal effects of angiotensin II (Ang II) signaling remain poorly understood. One particular mechanism of Ang II-mediated increases in presympathetic neuronal activity is through reductions in voltage-gated K⁺ currents. Another pathway that has profound effects on neuronal K⁺ currents and that has been previously implicated in Ang II-signaling is brain-derived neurotrophic factor (BDNF) activity through …

Classification Of Breast Cancer Patients Using Somatic Mutation Profiles And Machine Learning Approaches, Suleyman Vural

Theses & Dissertations

The high degree of heterogeneity observed in breast cancers makes it very difficult to classify cancer patients into distinct clinical subgroups and consequently limits the ability to devise effective therapeutic strategies. In this study, we explore the use of gene mutation profiles to classify, characterize and predict the subgroups of breast cancers. We analyzed the whole exome sequencing data from 358 ethnically similar breast cancer patients in The Cancer Genome Atlas (TCGA) project. Identified somatic and non-synonymous single nucleotide variants were assigned a quantitative score (C-score) that represents the extent of negative impact on the function of the gene. Using …

A Role For Ehd Family Endocytic Regulators In Endothelial Biology, Alexandra E. J. Moffitt

Theses & Dissertations

Endocytic trafficking is an essential process in eukaryotic cells, specifically for the transport of nutrients, membrane components, and receptors. Cargo destined for endocytic traffic is internalized at the cell surface via clathrin-dependent and clathrin-independent pathways, and brought to the early or sorting endosomes. From there, cargo is further trafficked to lysosomes for degradation, trafficked to other compartments in the cell, or recycled back to the cell surface (either directly or via the endocytic recycling compartment).

Mammalian C-terminal Eps15 homology domain-containing proteins, or EHD proteins (EHD1 to 4), are a family of highly conserved ATPases that function as key regulators of …

The Effect Of Body Mass Index On Graft Function And Kidney Transplant Outcomes, Morgan Galle

Theses & Dissertations

Background: When determining eligibility for kidney transplantation, body mass index (BMI) is often a debatable criterion for transplant due to the clinical indication, an elevated BMI has adverse effects on kidney transplant outcomes. There is a current gap in research on the effect BMI has on kidney transplant outcomes.

Purpose: The purpose of this study was to determine the role BMI plays in post-kidney transplant clinical outcomes including delayed graft function, new onset diabetes after transplant, wound complications, hospital length of stay, albumin, and readmissions to the hospital from initial hospitalization and at six months following kidney transplantation. The primary …

The Role Of Cxcr2 In Pancreatic Cancer Development And Progression, Abhilasha Purohit

Theses & Dissertations

This dissertation examines the role of CXCR2, a seven transmembrane G- protein coupled receptor, in mediating autocrine as well as paracrine mechanisms during pancreatic cancer progression. Data presented in the initial section demonstrates the aberrant expression of the CXCR2 biological axis in human pancreatic cancer tissue specimens. A study performed within the first section of this dissertation investigates the contribution of CXCR2 signaling in pancreatic cancer initiation. These studies have identified a novel role of CXCR2 in mediating KRAS^(G12D) -induced autocrine growth transformation of pancreatic cancer cells. The upregulation of the CXCR2 biological axis was found to be directly …

Atypical Protein Kinase C Dependent Polarized Cell Division Is Required For Myocardial Trabeculation, Derek L. Passer

Theses & Dissertations

A hallmark of cardiac development is the formation of myocardial trabeculations exclusively from the luminal surface of the primitive heart tube. Although a number of genetic defects in the endocardium (Grego-Bessa et al., 2007; Liu et al., 2010) and cardiac jelly (Camenisch et al., 2000) disrupt myocardial trabeculation, the role of cell polarity machinery in driving this process remains unclear. Herein, we demonstrate that atypical protein kinase C iota (Prkci) and its interacting partners of Par polarity complex are localized to the luminal side of luminal myocardial cells. Remarkably, a subset of these cells undergoes polarized cell division with the …

The Feedforward And Feedback Controls On Gait In Adults With Diabetes, Chun-Kai Huang

Theses & Dissertations

There are nearly 26 million people with diabetes mellitus (DM) in the US, and half of chronic DMs develop somatosensory deficits due to diabetic polyneuropathy or diabetic peripheral neuropathy (DPN). The absence or impaired somatosensory feedback (e.g. touch sensation or joint proprioception) resulted from the damage of large nerve fiber, and motor deficits such as attenuated muscle strength and abnormal plantar pressure of lower extremity have been identified in DPN, and these sensorimotor impairments lead to an increased number of falls. To reduce the risk of falling, a well-coordinated and adapted limb movement driven by the feedforward (anticipatory) and feedback …

Lgr5 Activates Tgfβ Signaling And Suppresses Metastasis In Colon Cancer, Xiaolin Zhou

Theses & Dissertations

Metastasis is the major cause of death in colorectal cancer patients, mainly due to the ineffectiveness of current therapies once metastases begin to form. Further insight into the biology of colorectal cancer metastasis is, therefore, essential in order to gain a greater understanding of this process and ultimately to develop better cancer therapies to prevent or target metastasis. LGR5 is leucine-rich repeat containing G protein-coupled receptor (GPCR) and was discovered as a marker for proliferating adult stem cells in the small intestine. LGR5 and its homologs LGR4 and LGR6 are receptors of R-spondins (RSPOs), which are secreted agonists of canonical …

Impact Of Estrogen Receptor Alpha On Sle1-Induced Loss Of Tolerance, Shayla D. Yoachim

Theses & Dissertations

The autoimmune disease lupus shows a significant female sex bias. This sex bias may be due to the ability of estrogens to promote loss of tolerance to chromatin, the initial loss of tolerance event in lupus. Previously, we demonstrated that the ability of estrogens to promote lupus in (NZBxNZW) F1 mice is dependent on signaling via estrogen receptor alpha (ERα). The Sle1 lupus susceptibility allele controls loss of tolerance to chromatin, and C57BL/6 (B6) mice carrying the Sle1 lose tolerance and develop anti-chromatin autoantibodies and spontaneously activated immune cells. Loss of tolerance occurs earlier and with a higher penetrance in …

Characteristics Of Exocytosis And Endocytosis In Photoreceptors, Karlene M. Cork

Theses & Dissertations

Photoreceptors signal changes in light intensity to downstream retinal neurons through the exocytosis of glutamate-containing synaptic vesicles. The maintenance of the vesicle exocytosis and endocytosis process is essential for ongoing synaptic signaling. This study investigated the properties of exocytosis and endocytosis in photoreceptors and their role in ongoing neurotransmission.

I used electrophysiology and imaging techniques to study the properties of vesicle exocytosis and endocytosis in photoreceptors. First, we examined baseline release in photoreceptors that occurs in the absence of depolarizing stimulation. We measured mEPSCs in whole cell patch clamp recordings from horizontal cells. After inhibiting Ca²⁺ influx and efflux …

Occupational Exposure To Isoflurane Anesthetic Gas In The Research Environment, Andrea R. Mulvenon

Theses & Dissertations

This dissertation is a compilation of studies related to the halogenated anesthetic gas isoflurane. Historically, halogenated anesthetic gases have been used in the health care industry. In 1977 the National Institute for Occupational Safety and Health (NIOSH) issued a recommended exposure limit (REL) of two parts per million (ppm) averaged over one hour of exposure for halogenated anesthetic gases (NIOSH 1977). The purpose of the standard was to protect healthcare workers from exposure to halothane, methoxyflurane, and chloroform. However, isoflurane only became available after the NIOSH REL was adopted. Therefore, the NIOSH REL is not directly applicable to isoflurane. Moreover, …

Role Of Hippo-Yap Signaling In Mitosis And Prostate Cancer, Lin Zhang

Theses & Dissertations

The Hippo pathway controls organ size and tumorigenesis by inhibiting cell proliferation and promoting apoptosis. KIBRA [kidney and brain expressed protein] is an upstream regulator of the Hippo-YAP signaling. The role KIBRA plays in mitosis has not been established. We show that KIBRA activates the Aurora kinases during mitosis and KIBRA promotes the phosphorylation of large tumor suppressor 2 by activating Aurora-A. We further show that knockdown of KIBRA causes mitotic abnormalities, including defects of spindle and centrosome formation and chromosome misalignment. The transcriptional co-activator with PDZ-binding motif is a downstream effector of the Hippo tumor suppressor pathway. In the …

Characterization Of The Replication Of Coxsackievirus B3 With A Mutationally Disrupted Cre(2c) And The Use Of Creatinine-Hydrochloride As An Antibacterial Agent, Shane E. Smithee

Theses & Dissertations

Following natural or experimental infection, and in cell culture, coxsackie B virus (CVB) RNA can persist for weeks in the absence of CPE yet with detectable viral RNA. Earlier studies in our laboratory demonstrated that this persistence produced viral RNA with up to 49 nucleotide deletions at the 5’ genomic terminus, partially degrading the cloverleaf (or domain I), an RNA structure that is required for efficient viral replication. A cis-acting replication element (CRE) in the 2C protein coding region [CRE(2C)] templates the addition of two uridine residues to the virus-encoded RNA replication primer, VPg, prior to genomic replication. Because …

Transcriptional And Post-Transcriptional Regulation Of Hepcidin And Iron Metabolism By Lipid Signaling In The Liver, Sizhao Lu

Theses & Dissertations

Although iron is required for essential biological processes, excess iron is detrimental due to oxidative damage induced by iron-mediated Fenton reactions, which promote tissue injury. Cellular iron uptake, transport and storage must therefore be tightly regulated. This task is accomplished mainly through hepcidin, the key iron-regulatory hormone. Hepcidin is synthesized primarily in hepatocytes as a circulatory antimicrobial peptide. It controls iron metabolism by inhibiting iron absorption from the duodenum and iron release from reticuloendothelial macrophages. Besides synthesizing hepcidin, the liver plays an important role in maintaining iron homeostasis by serving as the main storage organ for excess iron. Patients with …

Role Of Macrophages In Muscle Transfection With Pdna/Pluronic Formulation, Vivek Mahajan

Theses & Dissertations

Non-ionic amphiphilic block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), Pluronics, arranged in a tri-block structure PEO-PPO-PEO, have raised a considerable interest in skeletal muscle Gene Therapy. Previous studies have demonstrated that co-administration of Pluronics with naked plasmid DNA (pDNA) by direct i.m. injection enhanced transgene expression not only in muscle but also in distal lymphoid organs (spleen and lymph nodes) and this response was strain-dependent; not observed in athymic (BALB/c nu/nu) mouse; suggesting a role of immune cells in gene transfer to skeletal muscles. Therefore, we first evaluated the role of inflammation and inflammatory cells, on muscle …

Investigation Of Behavioral And Cellular Changes In The Maternal Immune Activation Model Of Autism Spectrum Disorders, Shreya Roy

Theses & Dissertations

Maternal infection during pregnancy, which leads to maternal immune activation (MIA), is an environmental risk factor for autism spectrum disorders (ASD). MIA can be induced in mice and their offspring exhibit behaviors that model the core symptoms of ASD. One of the core behavioral symptoms in ASD patients is presence of increased repetitive behavior, which is modeled by an increase in marble burying in MIA mice. It has been shown that the deficits seen in MIA mice are associated with the dysregulation of cytokine levels in the developing brain, specifically an increase in pro-inflammatory cytokines. In this thesis, I tested …

Development Of Polymer Peptide Conjugates For Enhanced Pancreatic Cancer Imaging, Wen Shi

Theses & Dissertations

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths in the US with very poor prognosis. All clinically available biomarkers and diagnostic tools either fail to detect early stage PDAC or suffer from low specificity and sensitivity. There is an urgent need for diagnostic agents with greater efficacy for PDAC detection and staging. Nanomaterials such as N-(2-Hydroxypropyl) methacrylamide (HPMA) copolymers can effectively target tumors, and offer novel opportunities for the development of effective diagnostic agents for cancer. However, a major problem of many nanomaterials-based diagnostics is their opsonization and sequestration by the mononuclear phagocyte system (MPS), leading …

Role Of The C-Terminus Of The Catalytic Subunit Of Translesion Synthesis Polymerase Ζ (Zeta) In Uv-Induced Mutagensis, Hollie M. Siebler

Theses & Dissertations

Cellular DNA is under constant attack by endogenous and exogenous DNA damaging agents that threaten genome integrity. Unrepaired DNA lesions often stall replicative DNA polymerases and are bypassed by translesion synthesis (TLS) to prevent replication fork collapse. TLS mechanisms are lesion- and species-specific, with prominent roles of specialized DNA polymerases with relaxed active sites. After incorporation of nucleotide(s) across from the lesion, the distorted primer termini are typically extended by DNA polymerase ζ (Pol ζ). As a result, Pol ζ is responsible for most DNA damage-induced mutations. Mechanisms of sequential polymerase switches and regulation of Pol ζ access to DNA …

Myeloid-Derived Suppressor Cells Contribute To The Subversion Of Innate Immunity During Staphylococcus Aureus Biofilm Infection, Cortney E. Heim

Theses & Dissertations

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature monocytes and granulocytes that are potent inhibitors of T cell activation. A role for MDSCs in bacterial infections has only recently emerged, and our laboratory was the first to demonstrate a functional role for MDSCs during Staphylococcus aureus (S. aureus) biofilm infection. Biofilm infections often lead to significant morbidity due to their recalcitrance to antibiotics and ability to subvert immune-mediated clearance by skewing the immune response toward an anti-inflammatory, pro-fibrotic phenotype. Therefore, we examined whether MDSCs could play a role in this process. CD11b⁺Gr-1⁺ MDSCs …

Characterization And Target Identification Of Non-Toxic Ikkβ Inhibitors For Anticancer Therapy, Elizabeth Blowers

Theses & Dissertations

IKKβ is a key kinase in the canonical NF-κB pathway. Transient activation of IKKβ is required for normal immune response while sustained activation has been implicated in cancer. To date, no IKKβ inhibitor has been approved for clinical use as a chemotherapeutic, likely due to unexpected toxicities associated with blocking the transient activation of IKKβ. We hypothesized that an IKKβ inhibitor that allows transient activation of IKKβ, but not sustained activation of IKKβ, could inhibit cancer growth without inducing toxicity.

As such, we identified a small molecule inhibitor, 13-197, that allows the transient activation of IKKβ but not the sustained …

Functional Characterization Of The Roles Of Endocytic Recycling Regulator Ehd1 Using In Vivo And In Vitro Analyses, Priyanka Arya

Theses & Dissertations

Endocytic recycling is a fundamental cellular process that allows the precise regulation of the membrane components and receptors at the cell surface. Recent studies have established that the C-terminal Eps15 homology domain-containing (EHD) proteins function as key regulators of this process. Four highly-conserved members of the EHD protein family in mammals, EHD1-EHD4, play shared as well as unique roles in endocytic trafficking. Studies presented here demonstrate a critical role of EHD1 in the normal ocular development in mice. Ehd1 knockout mice generated in our laboratory displayed gross ocular phenotypes including the anophthalmia, microphthalmia, and congenital cataracts. Hematoxylin and eosin (H&E) …

Effects Of Maternal Immune Activation And Repeated Maternal Separation On Postpartum Behaviors In The Female Rat Offspring, Shinnyi Chou

Theses & Dissertations

Early life stress can induce persistent brain and behavioral alterations. As a lifetime history of clinical symptoms similar to those caused by early adversities may predict postpartum dysfunctions, these stressors likely contribute to their etiology. Postpartum neuropsychiatric disorders (e.g. postpartum depression, anxiety and depression) are costly, yet due to the complex neuronal reorganization during this period, insights into how early adversities-induced CNS functional changes affect postpartum processes remain limited, especially under multiple stressors. Thus, there is a need to determine postpartum functions altered by early stress, in order to increase understandings of risks associated with postpartum maladaptations. Accordingly, this work …