Medical Sciences Commons^™

Genomic Instability And The Oncohistone H3k27m Drive Gliomagenesis In A Murine Model, Lee J. Pribyl

Theses and Dissertations (ETD)

Maintaining genome stability is crucial for human health and it is of particular importance in neural cells during early brain development. Genome maintenance occurs at two broad stages; surveillance during DNA replication and DNA damage repair in differentiating and mature cells. Neural cells are particularly sensitive to DNA strand breaks and defective DNA damage responses can result in detrimental effects on the nervous system, including cancer. Multiple DNA repair pathways play critical roles in preventing DNA damage accumulation in stem and neural progenitor cells. The mechanisms that protect progenitor genomes also suppress DNA mutations that can result in cancer. A …

Investigation Of A Novel Mitophagy Regulatory Pathway And Chemical Inducer, Jane E. Craig

Theses and Dissertations (ETD)

Mitochondria are vital organelles that coordinate cellular energy homeostasis and also have important roles in cell death. Therefore, the removal of damaged or excessive mitochondria through autophagy, a process called mitophagy, is critical for maintaining proper cellular function. Much of the research elucidating the mechanism and regulation of autophagy was performed in yeast cells, so there is still a lot of mystery surrounding how mitophagy is promoted and regulated in mammals in general and in different tissues. The most well understood mechanism involved in mitophagy is the PINK1-PARKN pathway. However, studies often rely on severe mitochondrial damage using CCCP that …

Mean Arterial Pressure In Acute Ischemic Stroke Study, Mary Angela Grove

Theses and Dissertations (ETD)

Background. There is little, if any, evidence available on the validation of blood pressure (BP) measurements obtained in the acute care setting. Despite this, acute stroke practitioners trust and rely on non-invasive blood pressure (NIBP) devices to guide acute ischemic stroke (AIS) patients’ treatment. Although systolic blood pressure (SBP) has been found to be the most unreliable measurement displayed on NIBP devices, treatment decisions for AIS are based on them. Today, 25 years after the FDA’s approval of alteplase, practitioners continue to use BP parameters of 185/110 and 180/105 to guide the initiation of alteplase bolus and infusion, although the …

Mechanisms Of Bak Activation In The Initiation Of Mitochondrial Apoptosis, Geetika Singh

Theses and Dissertations (ETD)

Mitochondrial apoptosis is crucial for normal mammalian development and adult homeostasis being regulated by B-Cell Lymphoma-2 (BCL-2) proteins. Deregulation of BCL-2 proteins form the basis for myriad of human pathologies including cancer and autoimmune diseases. Therefore, BCL-2 proteins are considered key therapeutic targets. BCL-2 homologous antagonist/killer (BAK) is an effector of outer mitochondrial membrane (OMM) pemeabilization or mitochondrial poration. Despite progress in understanding BAK-mediated mitochondrial poration, the underlying multi-step mechanism is not clearly defined. Here, we provide mechanistic details on the early steps in this process related to BAK activation, including transient direct activation and autoactivation. We demonstrate for the …

Selective Targeting Of Cyp3a5 Through Chemical And Genetic Approaches, William C. Wright

Theses and Dissertations (ETD)

Cytochrome P450 enzymes function to catalyze a wide range of reactions important for various biological processes. In humans, the CYP3A subfamily is particularly critical for drug response. Within this family are CYP3A4 and CYP3A5, which collectively metabolize greater than half of all currently prescribed drugs. These promiscuous enzymes can bind a broad and structurally diverse array of compounds, in turn leading to an increased risk of their modulation via small molecules. In the case of CYP3A5, which is over-expressed in some cancers, this leads to chemoresistance. Such aberrant expression and corresponding drug resistance merit a need to selectively target CYP3A5. …

Understanding Human Astrovirus From Pathogenesis To Treatment, Virginia Hargest

Theses and Dissertations (ETD)

While human astroviruses (HAstV) were discovered nearly 45 years ago, these small positive-sense RNA viruses remain critically understudied. These studies provide fundamental new research on astrovirus pathogenesis and disruption of the gut epithelium by induction of epithelial-mesenchymal transition (EMT) following astrovirus infection. Here we characterize HAstV-induced EMT as an upregulation of SNAI1 and VIM with a down regulation of CDH1 and OCLN, loss of cell-cell junctions most notably at 18 hours post-infection (hpi), and loss of cellular polarity by 24 hpi. While active transforming growth factor- (TGF-) increases during HAstV infection, inhibition of TGF- signaling does not hinder EMT induction. …

Renal And Cardiovascular Outcomes Associated With Cannabis Use In Veterans With Advanced Chronic Kidney Disease Transitioning To Dialysis, Praveen Kumar Potukuchi

Theses and Dissertations (ETD)

Background: Legalization of cannabis and its constituents may lead to increased exposure of a higher number of consumers to cannabis use, including those with chronic kidney disease (CKD). We expect increase in cannabis use, especially, in patients with compromised kidney function. However, there is sparse literature on the effects of cannabis use on cardiorenal and mortality outcomes among patients with advanced CKD. Objectives: The main goal of the current study was to examine the effect of cannabis use on renal and cerebrovascular outcomes as well as mortality in patients with advanced CKD. Using a nationwide cohort of US veterans with …

Biochemical And Structural Characterization Of The Atg8/Lc3 Lipidation Pathway, Yumei Zheng

Theses and Dissertations (ETD)

Atg8 and its eukaryotic orthologues LC3 and GARBARAP family proteins (referred here to Atg8 family proteins) play crucial roles in autophagy through their covalent ligation to lipids, typically phosphatidylethanolamine (PE), in a process known as lipidation. Lipidation of Atg8 family proteins regulates numerous facets of the autophagy process, including regulating expansion of the phagophore membrane, recruiting selected cargoes for degradation, and providing an autophagosome membrane-bound platform mediating dynamic interactions with other regulatory proteins. Atg8 family proteins are ubiquitin-like proteins (UBLs), and their lipidation involves a divergent UBL conjugation cascade including Atg7, Atg3, and Atg12–Atg5-Atg16 acting as E1, E2, and E3 …

Integrated Multimodal Genomic Analyses Reveal Novel Mechanisms Of Glucocorticoid Resistance In Acute Lymphoblastic Leukemia, Robert J. Autry

Theses and Dissertations (ETD)

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Much has been discovered in recent decades regarding ALL biology, and the outcome of patients with ALL has vastly improved, especially in pediatric ALL patients. Despite very promising overall cure rates, patients who relapse have a greatly decreased prognosis with survival rates ranging from 30-60%. These numbers stand to improve even further with new targeted therapies that seek to improve or maintain cure rates while reducing treatment related toxicities which affect patients both acutely and chronically. Glucocorticoids (GCs) are essential components of modern chemotherapeutic intervention for ALL. Resistance to glucocorticoids …

Unraveling Molecular Mechanisms Underlying The Development Of Unconventional T Cells, Daniel Eduardo Bastardo Blanco

Theses and Dissertations (ETD)

The thymus supports and guides the generation of a diverse repertoire of mature T cells from precursors derived from the bone marrow. In addition to conventional CD4 and CD8 T cells, innate-like T cells also develop in the thymus and share features of the adaptive and the innate immune system. These ‘unconventional’ T cells have emerging roles in tissue homeostasis and disease, but the molecular mechanisms underpinning their development remain elusive. In this study, we uncovered the roles of the molecules RAPTOR and PTEN in the thymic development of unconventional T cells. Capitalizing on genetic deletion of RAPTOR, we found …

Delineating The Mechanisms Of Misfolded Endoplasmic Reticulum (Er) Luminal Protein Retrotranslocation For Er-Associated Degradation, Christina Oikonomou

Theses and Dissertations (ETD)

Secreted, plasma membrane, and resident proteins of the secretory pathway are synthesized in the endoplasmic reticulum (ER) where they undergo post-translational modifications, oxidative folding, and subunit assembly in tightly monitored processes. An ER quality control (ERQC) system oversees protein maturation and ensures that only those reaching their native state will continue trafficking into the secretory pathway to reach their final destinations. Proteins that fail quality control must be recognized and eliminated to maintain ER proteostasis. The ER-associated degradation (ERAD) was discovered nearly 30 years ago and entails the identification of improperly matured secretory pathway proteins and their retrotranslocation to the …

Reverse Zoonosis Of Pandemic A(H1n1)Pdm09 Influenza Viruses At The Swine/Human Interface, Daniel Gene Darnell

Theses and Dissertations (ETD)

The 2009 pandemic influenza A(H1N1)pdm09 virus emerged from the swine population. Despite frequent zoonotic events, swine influenza viruses had not become established in humans previously and little is known about host-barriers which prevent swine influenza viruses from efficiently infecting humans. Thus, the emergence of the H1N1pdm09 viruses in humans and the subsequent reverse zoonoses back to swine offered an extremely valuable opportunity to expand current knowledge. We used our active swine farm surveillance platform in combination with viruses from the USDA surveillance program to look for evidence of interspecies transmission of H1N1pdm09 viruses in the US. We found phylogenetic evidence …

Fear Learning And The Olfactory Bulb: Neural Correlates Of Behavioral Fear Generalization, Jordan Marie Ross

Theses and Dissertations (ETD)

The exploration of how learning alters neural coding to guide behaviors remains fundamental to neuroscience. At the most basic level, the ability for organisms to flexibly adapt to changing environments and situations is paramount to biological success and often manifests in behavioral responses controlled by neural activity. For example, organisms must modify their behavior to defensive responses in the face of biological threat. Neural circuitry is involved in coordinating an initial defensive behavioral response but must undergo reorganization in order to reliably employ defensive responses in subsequent encounters based on a cue that signals imminent danger. One such form of …

Using Genetic Diversity To Understand Susceptibility To Cognitive Decline In Aging And Alzheimer’S Disease, Sarah M. Neuner

Theses and Dissertations (ETD)

An individual's genetic makeup plays an important role in determining susceptibility to cognitive aging and transition to dementia such as Alzheimer's disease (AD). Identifying the specific genetic variants that contribute to cognitive aging and AD may aid in early diagnosis of at-risk patients, as well as identify novel therapeutics targets to treat or prevent development of symptoms. Challenges to identifying these specific genes in human studies include complex genetics, difficulty in controlling environmental factors, and limited access to human brain tissue. Here, we turned to genetically diverse mice from the BXD genetic reference panel (GRP) to overcome some of the …

Transcriptional Regulation Of Nlrc4 Inflammasome By Irf8, Ein Lee

Theses and Dissertations (ETD)

The NLRC4 inflammasome is a crucial part of the innate immune response against bacterial infections. We found that NLRC4 inflammasome activation in bone marrow-derived macrophages (BMDMs) is greatly dependent on interferon regulatory factor 8 (IRF8). NLRC4-mediated caspase-1 activation and subsequent production of the inflammasome-dependent cytokines IL-1β and IL-18 and cell death were impaired in IRF8-deficient cells. IRF8 mediated the transcription of genes encoding NAIPs, the receptors for NLRC4 inflammasome, which recognize bacterial flagellin and type III secretion system (T3SS) proteins. IRF8 was critical for host survival following infection with Salmonella Typhimurium or Burkholderia thailandensis. Furthermore, mice deficient in IRF8 were …

Investigation Of Cell-Type-Specific Effects And Synergistic Interactions Between Genes In Duplication 15q Syndrome, Kevin A. Hope

Theses and Dissertations (ETD)

Duplication 15q syndrome (Dup15q) is a genetic disorder caused by duplications of the 15q11.2-q13.1 region and is characterized by developmental delay, autism spectrum disorder, and treatment resistant epilepsy. Extra copies of the E3 ubiquitin ligase UBE3A and elevated levels of UBE3A expression in neurons are thought to be the primary cause of Dup15q phenotypes. However, animal models overexpressing UBE3A in neurons have not successfully recapitulated all aspects of Dup15q syndrome, especially epilepsy. Here, we used Drosophila melanogaster (fruit flies) to investigate Dup15q syndrome. In Chapter 2 we explored whether Dube3a, the Drosophila homolog of UBE3A, is imprinted in the fly …

Roles Of Γδ T Cells In Influenza Infections And Methods For Tcr Expression And Characterization, Xizhi Guo

Theses and Dissertations (ETD)

"Influenza virus is a significant pathogen in humans and animals with the ability to cause extensive morbidity and mortality. Exuberant immune responses associated with immune cell migration/activation and cytokine/chemokine release, can be induced after infections. Recent studies have painted a complex picture of viral clearance and tissue repair in adults. The immune responses in neonatal influenza infections and the potential methods to engineer antigen-specific T cells for immunotherapy against cancers and infections will be the focus of this dissertation." "Compared to adults, infants suffer higher rates of hospitalization, severe clinical complications, and mortality due to influenza infection. We found that …

The Tumor Microenvironment Regulates Retinoblastoma Cell Survival, Zachary K. Goldsmith

Theses and Dissertations (ETD)

Retinoblastoma (Rb) is the most common intraocular malignancy in children comprising 4% of all pediatric tumors. Early intervention increases survival rates up to 95% in developed countries; being survival rates associated to socio-economic status. Despite the high survival rates in developed countries, preservation of the eye and vision are continuing challenges in the management of Rb. Vitreous seeds constitute the greatest challenge in treatment of Rb. The unique location of these seeds within the vitreous makes them difficult to treat. Viable seeds showed reduced proliferative capacity and metabolism. making the majority refractory to current chemotherapeutics. This prompted the development of …

The Role Of Bip Co-Chaperone Sil1 In Marinesco-Sjögren Syndrome Pathogenesis, Viraj Paresh Ichhaporia

Theses and Dissertations (ETD)

Marinesco-Sjögren syndrome (MSS) is a rare, autosomal recessive, multisystem disorder, which is characterized by cerebellar ataxia, early-onset bilateral cataracts, and progressive myopathy amongst other symptoms. MSS has been attributed to mutations in the SIL1 gene, which encodes a nucleotide exchange factor for the endoplasmicreticulum- resident Hsp70 chaperone, BiP. To date, there are 46 MSS-associated mutations that have been reported in SIL1, which occur throughout this gene and are predicted to result in a loss of SIL1’s function. The large majority of these mutations cause deletions of large fractions of the SIL1 protein. Nine MSS-associated mutations are particularly interesting because they …

Signaling Induced By Inflammatory Mediators In The Rodent Pulmonary Microvasculature, Rachel Escue Helms

Theses and Dissertations (ETD)

Acute lung inflammation (ALI), stemming from a disproportionate and detrimental immune response, may arise from or complicate other disease states, leading to the often-fatal acute respiratory distress syndrome (ARDS). Because of the many culpable factors and differing points of induction, pinning down the signaling mechanisms involved in the morbidity of this disorder as well as defining an effective treatment has proved problematic. However, the most detrimental characteristic of this condition is seen regardless of the development of the response: increased microvascular permeability. Because of the architecture and the size of the pulmonary microvascular network, the lungs have a resident, sequestered …

Targeting The Colchicine Binding Site On Tubulin To Overcome Multidrug Resistance And Anticancer Efficacy Of Selective Survivin Inhibitors, Kinsle E. Arnst

Theses and Dissertations (ETD)

Tubulin inhibitors are widely used as chemotherapeutic agents, and their successis attributed to their ability to target microtubule dynamics and disrupt critical cellular functions including cell signaling, motility, intracellular trafficking, and mitosis. Interference with microtubule dynamics consequently disrupts mitotic progression and ultimately leads to apoptosis, validating microtubule dynamics as an excellent target for anticancer agents. While this class of drug has proven to be effective against many cancer types, the clinical efficacy of current tubulin inhibitors is often limited by the development of multidrug resistance. The most common form of resistance to these agents arises from the overexpression of drug …

The Role Of Exosomal Transport Of Viral Agents In Persistent Hiv Pathogenesis, Benjamin J. Patters

Theses and Dissertations (ETD)

Human immunodeficiency virus (HIV) infection, despite great advances in antiretroviral therapy (ART), remains a lifelong affliction. Though current treatment regimens can effectively suppress viral load to undetectable levels and preserve healthy immune function, they cannot fully alleviate all symptoms caused by the presence of the virus, such as HIV-associated neurocognitive disorders (HAND). Exosomes are small vesicles that transport cellular proteins, RNA, and small molecules between cells as a mechanism of intercellular communication. Recent research has shown that HIV proteins and RNA can be packaged into exosomes and transported between cells, to pathogenic effect. This review summarizes the current knowledge on …

Roles Of Cytosolic Nucleic Acid Sensors In Cancer And Infection, Qifan Zhu

Theses and Dissertations (ETD)

Pattern recognition receptors are innate immune sensors that recognize pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) with crucial roles in host defense against microbial infection, autoimmune diseases and cancer. Cytosolic nucleic acids including DNA and RNA originate from pathogens or self-cells, which form major groups of PAMPs and DAMPs. A range of nucleic acid sensors have evolved to sense various types of nucleic acids. How different DNA-sensing pathways regulate microbial infection and cancer is the focus of this dissertation.

Stimulator of IFN genes (STING) is a cytosolic innate immune sensor for cyclic dinucleotides that also serves a dual …

Pathogenicity And Protection Mediated By A Single Tcrβ In Experimental Autoimmune Encephalomyelitis, Tianhua Wu

Theses and Dissertations (ETD)

How the TCR repertoire, together with risk-associated major histocompatibility complex (MHC), imposes susceptibility for autoimmune disease is not fully understood. A small fraction of TCR α or β chains are “public”, and are shared by most individuals.High-throughput sequencing of the mouse TCRβ repertoire during myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmuneencephalomyelitis (EAE) identified a public TCRβ chain, TCRβ1, which was highly shared among individual mice and preferentially deployed during EAE. Retrogenic expression of TCRβ1 resulted in spontaneous early-onset EAE in mice with high penetrance and severity, despite being paired with a diverse endogenous TCRα repertoire. To further study autoimmunity conferred by …

An Interface Of The Taste And Reward Systems In The Brainstem And Its Role In Feeding, Louis Saites

Theses and Dissertations (ETD)

We eat what tastes good. We also eat because it is necessary for our health. In fact, some of the most nutritious foods (e.g., vegetables) are often less appetizing, and the tastiest (e.g., fast food, ice cream) may be the least healthy. Despite the former, we may also have a lower limit of what we accept at which point nutrition becomes irrelevant (e.g., “spinach is just too yucky”). Further, we may eat unhealthily because of overwhelming urges. We investigated the complex interactions of taste and feeding at the neurobiological level using the experiments described.

In one sense, this neurobiology begins …

Molecular Interplay Of Chromatin Remodeling Factor Brg1 And Transcription Factor Stat3 Regulates Stemness, Chemosensitivity And Tumorigenicity Of Glioma Tumor Initiating Cells, Debolina Ganguly

Theses and Dissertations (ETD)

Glioblastoma Multiforme (GBM) is an aggressive brain tumor, characterized by high cellular heterogeneity, is refractory to treatment and has dismal prognosis. These characteristics of GBM have suggested the presence of stem-like cells that have the ability to initiate and maintain tumors of a heterogeneous nature, and bestow resistance to current therapeutic regimens. It is therefore imperative to identify the dysregulated molecular pathways which enable the maintenance of these cells in a stem-like state in order to inform strategies to therapeutically target them.

In this study, we investigated the role of the Y705 and S727 phosphorylation domains of STAT3, a multifunctional …

Pip2 Modulation Of Afterhyperpolarizations In Magnocellular Supraoptic Neurons, Matthew Karl Kirchner

Theses and Dissertations (ETD)

Magnocellular neurosecretory cells (MNCs) are large oxytocin (OT)- and vasopressin (VP)-releasing neurons that secrete these hormones into the circulatory system in response to physiological stimuli. These cells exhibit unique phasic and burst firing patterns to release these peptides into the circulatory system where they primarily control milk ejection and parturition (OT) as well as salt-water balance and vasoconstriction (VP). This firing is underlain by intrinsic ionic mechanisms that shape the duration and frequency of these bursts. One of these mechanisms is the Ca2+-dependent afterhyperpolarization (AHP), which activates during bursts and causes spike frequency adaptation. This afterhyperpolarization has three distinct conductances: …

Role Of Smarce1 And Bhlhe40 In Breast Cancer Metastasis, Aarti Sethuraman

Theses and Dissertations (ETD)

No abstract provided.

Novel Determinants That Influence Azole Susceptibility In Candida Glabrata And Candida Albicans, Sarah Garland Whaley

Theses and Dissertations (ETD)

Despite the scientific and medical communities’ best efforts, the incidence of fungal infections in susceptible populations continues to rise. The most common cause of these opportunistic fungal infections is Candida. In fact, Candida is the fourth most common pathogen associated with nosocomial blood stream infections. Reported mortality rates for patients with candidemia vary, but have not decreased in the past fifteen years and are reported to be as high as 50%. Candida glabrata, second only to Candida albicans among Candida infections, expresses high rates of resistance to treatment with arguably the best class of currently available antifungals - …

Protein Trafficking Of Bk Channel Β1 Subunits In Cerebral Artery Myocytes, Xue Zhai

Theses and Dissertations (ETD)

Rationale: Large-conductance calcium (Ca²⁺)-activated potassium channels (BK) are expressed in arterial myocytes to control arterial contractility. It is composed of pore- forming BKα and auxiliary β1 subunits. Auxiliary β1 subunits associate with BKα which modulate Ca²⁺ sensitivity of BK channel. Previous data showed that BKα locates at cell membrane, whereas β1 subunits are primarily intracellular which regulated by Rab11A- positive recycling endosomes. Endothelin-1 (ET-1), a vasoconstrictor, induces contraction of myocytes. ET-1 inhibits BK channel but mechanisms are not fully understood. It is unclear that vasoconstrictors regulate the cellular distribution of BK channels. Furthermore, BK channels are involved …