Life Sciences Commons^™

Understanding The Roles Of Dna Methylation And Mecp2 In Neuronal Enhancer Control, Adam Clemens

Arts & Sciences Electronic Theses and Dissertations

The development of organisms relies on complex spatial and temporal patterning of gene expression to define cell types and facilitate their functions. Cis-regulatory elements in our genome are responsible for the control of gene expression across tissues and cell types. Regulation of these elements themselves depends on a balance of activation and repression through epigenetic modifications and molecular regulatory components. Disruption of cis-regulatory element control is emerging as a cause of neurodevelopmental disease. An important contributor to gene regulation in development is methylation of cytosine in DNA, disruption of which has been associated with disease. Notably, while all cell types …

Examining Early Interactions Between Innate Airway Resident Immune Cells And Mtb-Specific Factors During Pulmonary Infection With Mycobacterium Tuberculosis, Micah D. Dunlap

Arts & Sciences Electronic Theses and Dissertations

Mycobacterium tuberculosis (Mtb) is the leading cause of death by an infectious agent in the world today, infecting roughly one quarter of humans. Despite this, the mechanisms of early pathogenesis and host protective innate immune responses remain poorly understood and uncharacterized.

Lung resident Alveolar Macrophages (AMs) are the first host contact with Mtb bacilli after inhalation and are thus key mediators of the early pulmonary immune response. AMs are generally believed to reside entirely in the airway, but it was recently demonstrated that they have the capacity to egress and enter into granulomas during pulmonary infection with hypervirulent Mtb. Furthermore, …

Visual And Non-Visual Control Of Movement: The Role Of Proprioception In Upper Limb Function After Stroke, Nathan A. Baune

Arts & Sciences Electronic Theses and Dissertations

This dissertation presents a series of studies into human reach and grasp, focusing on the neural systems and behaviors of upper-limb action that underly performance under varied sensory conditions: specifically, acting with and without visual feedback of the limb and under typical or impaired proprioceptive sensation (proprioceptive decline with aging and proprioceptive deficit following stroke). Under typical conditions, a combination of visual and non-visual (e.g., proprioception) sources of information are used to guide action. In the instance of stroke survivors or elderly individuals with proprioceptive deficits/decline, there may be a necessary reliance on visual information to perform. The studies are …

Contribution Of Tgf-B Signaling To The Pathogenesis Of Myeloproliferative Neoplasms, Juo-Chin Yao

Arts & Sciences Electronic Theses and Dissertations

TGF-b expression is increased in most cases of myeloproliferative neoplasms (MPNs); however, its contribution to disease pathogenesis is not well understood. Here, we explore two specific hypotheses. First, we hypothesize that increased TGF-b signaling in mesenchymal stromal cells contributes to the development of myelofibrosis. Second, we hypothesize that Jak2 mutated hematopoietic stem cells (HSCs) are resistant to the growth suppressive effect of TGF-b, conferring a fitness advantage that contributes to their expansion in MPNs and clonal hematopoiesis. To test the first hypothesis, we abrogated TGF-b signaling in mesenchymal stem/progenitor cells by deleting Tgfbr2 using a doxycycline-repressible Osterix-Cre transgene (Osx-Cre), which …

Functional Interrogation Of Jak2 And Asxl1 Mutations In Myeloproliferative Neoplasms, Taylor Brost Collins

Arts & Sciences Electronic Theses and Dissertations

JAK2 V617F is the most frequent mutation found in myeloproliferative neoplasms (MPNs), with 50-60% of myelofibrosis (MF) patients harboring this mutation. Mutations in ASXL1 often co-occur with JAK2 V617F and are associated with decreased survival and increased risk of transformation to secondary acute myeloid leukemia. How mutant ASXL1 contributes to the MPN disease phenotype and confers poor prognosis is not fully understood. Asxl1 mutation knock-in mouse models present with a relatively modest phenotype, following a long latency period and ASXL1 mutations have not been modeled in combination with JAK2 V617F. The field lacks human model systems that focus on how …

The Role Of Mature Secretory Cells In Gastrointestinal Regeneration, Megan Deanna Radyk

Arts & Sciences Electronic Theses and Dissertations

Differentiated cells exhibit the ability to adjust their cell fate and become more progenitor-like after wide-scale tissue injury. This inherent cell plasticity is shown across many tissues and organisms and is a conserved behavior that ensures organ function even in a chronic injury setting. At the tissue level, the change in cell fate from a differentiated cell to one with more progenitor properties can be identified as metaplasia. Importantly, metaplasias, like Spasmolytic Polypeptide-Expressing Metaplasia (SPEM) in the stomach and Acinar-to-Ductal Metaplasia (ADM) in the pancreas, are risk factors for the development of adenocarcinoma. Thus, understanding the cellular and molecular mechanisms …

Thermodynamics And Conformational Heterogeneity Of Recbcd Binding To Dna Ends, Linxuan Hao

Arts & Sciences Electronic Theses and Dissertations

E. coli RecBCD is crucial in initiating repair of double stranded (ds) DNA breaks. It is a heterotrimeric helicase and nuclease complex possessing two ATPase motors, RecB and RecD, and a regulatory subunit without ATPase activity, RecC. The RecB subunit also contains a 30kDa nuclease domain (RecBNuc) that, according to published structural data, is situated over 60Å away from the site of dsDNA binding. Surprisingly, we have shown in previous studies that deletion of RecBNuc to form RecBΔNucCD affects its dsDNA unwinding properties. The mechanism by which RecBNuc influences RecBCD dsDNA unwinding is unclear. In this thesis, equilibrium binding techniques, …

Identify Genetic And Epigenetic Abnormalities Associated With Therapeutic Vulnerability In Human Cancers, Wen-Wei Liang

Arts & Sciences Electronic Theses and Dissertations

Human cancer is a complex and dynamic disease with mutational, spatial, and temporal heterogeneity. There has been a concerted effort to address the heterogeneity by profiling large-scale multiomic datasets with an emphasis on abnormalities such as DNA mutations at coding regions and structural variants. However, a systematic analysis of alterations at “dark matter” is lacking – including DNA slippage events at microsatellite sequences, gene fusions arising from genomic rearrangements, and aberrant DNA methylations at promoter regions. This dissertation focus on developing data-driven computational analysis pipelines to study the patterns of microsatellite instability, gene fusions, and aberrant DNA methylation, and their …

Ascension And Adhesion Of Uropathogenic Escherichia Coli During Pyelonephritis, Lisa Kristine Mclellan

Arts & Sciences Electronic Theses and Dissertations

The ability of uropathogenic Escherichia coli (UPEC) to successfully establish an infection within the urinary tract relies on the pathogen to be able to navigate the complex interactions between pathogen and host. During a urinary tract infection (UTI), UPEC must ascend, adhere, and form bacterial communities in various infection niches, from the bladder (cystitis) to the kidneys (pyelonephritis). Each of these steps is critical for bacterial survival, and host and pathogen factors required at each stage can vary depending on host sex and anatomic niche. Preclinical modeling of pyelonephritis and sex effects on UTI has been limited due to the …

Mass Spectrometry-Based Strategies In Protein Higher Order Structure Analysis: Fundamentals And Applications In Protein-Ligand Interactions, Xiaoran Liu

Arts & Sciences Electronic Theses and Dissertations

Protein ligand interaction is a fundamental question in biology and biochemistry, and many approaches including X-ray crystallography, nuclear magnetic resonance, cryogenic electron microscopy, mass spectroscopy (MS), infrared spectroscopy, circular dichroism, fluorescence spectroscopy and many others have been applied to address this question. Among these techniques, mass spectroscopy has the advantage of high throughput, low sample amount requirement, and mid-to-high spatial resolution. One of the MS-based approaches is protein footprinting, which utilizes labeling reagents to map the solvent accessible surface of the protein of interest thus deliver structural information. Irreversible labeling is represented by covalent labeling and radical labeling, in which …

Prodrug Activation In Staphylococci And The Implications For Antimicrobial Development, Justin J. Miller

Arts & Sciences Electronic Theses and Dissertations

Antibiotic resistance is an increasing concern for global health care, with some estimates suggesting that 10 million people will die from antibiotic resistant infections in the year 2050. Fueling this prospect, few antimicrobials are being actively developed and recently commercial entities have fled from the development of new anti-infectives. New antimicrobials and drug development strategies are urgently needed to revitalize this critical pipeline. While many putative antibiotics demonstrate promising in vitro potency, they routinely fail in vivo due to poor drug-like properties (e.g. oral bioavailability, serum-half life, toxicity) resulting in overly expensive drug development pipelines. Fortunately, drug-like properties can be …

Targeting The Phgdh-Mtor Metabolic Axis In Osteosarcoma, Richa Rathore

Arts & Sciences Electronic Theses and Dissertations

Altering cellular energy metabolism has been highlighted as one of the emerging hallmarks of cancer. The reprogramming of bioenergetic pathways towards enhanced glycolysis, rather than the mitochondrial oxidative phosphorylation indicative of normal cells, results in increased biomass production and is associated with the activation of various oncogenes. The increased or decreased expression of key metabolic enzymes has been identified as a potential family of biomarkers that could serve as the targets for novel metabolic-based therapies in cancer.

The serine, glycine, and one-carbon (SGOC) metabolism pathway consists of a series of enzymes and metabolites that drive protein and lipid production, enhanced …

Molecular Strategies To Overcome Antibiotic Resistance, Luting Fang

Arts & Sciences Electronic Theses and Dissertations

Antibiotics have greatly reduced the number of deaths caused by infectious diseases for the last 70 years, but as a result of overuse, antimicrobial resistance emerged. Resistance is the major reason why most traditional antibiotics currently have reduced clinical efficacy. However, there is still a drive to overcome this resistance in a variety of ways. There are two main avenues of research to overcome resistance; to discover and develop new drug candidates acting on new targets and pathways, and to determine the mechanisms of antibiotic resistance in order to combat it through multi-drug therapies, bringing back the effectiveness of antibiotics …

Of Mice And Toddlers: A Cross-Species Investigation Of The Social Motivation Theory Of Autism, Claire Weichselbaum

Arts & Sciences Electronic Theses and Dissertations

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by social impairments and restricted, repetitive behaviors. Despite its growing prevalence, ASD remains poorly understood. One explanation for its social symptoms that has gained prominence in recent years is the Social Motivation Theory, which proposes a reduced motivation for social engagement as the underlying cause of impaired social functioning in ASD. While typically developing individuals find social interaction inherently rewarding, this theory suggests that people who develop ASD do not experience the same attraction to social stimuli and therefore miss out on critical social learning opportunities, hampering the development of …

Evaluating Everyday Behaviors With Delayed And/Or Probabilistic Consequences Through A Discounting Framework, Yu-Hua Yeh

Arts & Sciences Electronic Theses and Dissertations

Delay and probability discounting refer to the decrease in subjective value of an outcome as the time until its occurrence increases and the likelihood of its occurrence decreases, respectively. Significant differences between the discounting of gains and losses, either delayed or probabilistic, have been documented in the literature. A recent study that investigated similarities and differences between the discounting of delayed gains, delayed losses, and probabilistic losses, found qualitative individual differences (i.e., subgroups) present only in the discounting of losses (Yeh et al., 2020). The current study expanded the previous investigation of subgroups to the discounting of probabilistic gains (Experiment …

Investigating The Integration-Independent Role Of Hiv-1 In In The Viral Life Cycle, Jennifer Elliott

Arts & Sciences Electronic Theses and Dissertations

Human immunodeficiency virus type 1 (HIV-1) relies on a handful of essential enzymes for replication. Among these, the viral integrase enzyme (IN) plays a pivotal role in the viral life cycle by catalyzing the integration of the reverse-transcribed viral DNA into the host chromosome. While integration is the canonical role of IN, new research has uncovered an additional vital role for IN during virion morphogenesis. This dissertation elucidates how IN contributes to proper packaging of the viral RNA genome (vRNA) within the viral capsid and examines the fate of improperly formed viral particles in target cells.IN is proposed to mediate …

Protein Synthesis Adaptation To The Au-Rich Transcriptome Of Plasmodium Falciparum, Jessey Lee Erath

Arts & Sciences Electronic Theses and Dissertations

The process of protein synthesis whereby a messenger RNA is decoded into an amino acid chainis conserved among the domains. Fastidious protein synthesis is necessary for organism survival. However, exceptions negatively affecting the mRNA translation cycle – inadvertently or by design – may occur. Polyadenosine tracts are one such motif causing ribosomal stalling and frameshifting in almost all organisms tested thus far; save Plasmodium spp. Thus, with ~60% of their protein-coding genome harboring polyadenosine tracts, the elucidation of such paradigm-breaking adaptations enabling Plasmodium spp. to translate this typically problematic motif without issue is salient from both basic science and clinical …

Relating Spontaneous Activity And Cognitive States Via Neurodynamic Modeling, Matthew Singh

Arts & Sciences Electronic Theses and Dissertations

Stimulus-free brain dynamics form the basis of current knowledge concerning functional integration and segregation within the human brain. These relationships are typically described in terms of resting-state brain networks—regions which spontaneously coactivate. However, despite the interest in the anatomical mechanisms and biobehavioral correlates of stimulus-free brain dynamics, little is known regarding the relation between spontaneous brain dynamics and task-evoked activity. In particular, no computational framework has been previously proposed to unite spontaneous and task dynamics under a single, data-driven model. Model development in this domain will provide new insight regarding the mechanisms by which exogeneous stimuli and intrinsic neural circuitry …

Understanding And Exploiting Protein Allostery And Dynamics Using Molecular Simulations, Sukrit Singh

Arts & Sciences Electronic Theses and Dissertations

Protein conformational landscapes contain much of the functionally relevant information that is useful for understanding biological processes at the chemical scale. Understanding and mapping out these conformational landscapescan provide valuable insight into protein behaviors and biological phenomena, and has relevance to the process of therapeutic design.

While structural biology methods have been transformative in studying protein dynamics, they are limited by technicallimitations and have inherent resolution limits. Molecular dynamics (MD) simulations are a powerful tool for exploring conformational landscapes, and provide atomic-scale information that is useful in understanding protein behaviors. With recent advances in generating datasets of large timescale simulations …

Understand And Predict Microbiome And Resistome Dynamics In Response To Perturbations Across Diverse Populations And Environments, Manish Boolchandani

Arts & Sciences Electronic Theses and Dissertations

Complex microbial communities are at the interface of human, animal and environment interconnected ecosystem, where they can move within and between these entities. These microbial communities are mostly beneficial, maintaining the host health and homeostatic state. However, these communities can also serve as reservoirs of antibiotic resistance (AR) genes that may disseminate to pathogen bacteria, compromising the treatment options. Like other microbial communities, human gut microbiome is highly dynamic and can get acutely perturbed with the changes in the habitat, diet, lifestyle and disease. A perturbed gut community structure has profound impact on the host health and physiology. Use of …

Computational Analysis Of Non-Cpg Dna Methylation In The Mammalian Nervous System, Dennis Yawen Wu

Arts & Sciences Electronic Theses and Dissertations

Noncanonical forms of DNA methylation, especially non-CpG DNA methylation, play essential roles in the neuronal epigenome, and have only recently begun to be characterized. While most DNA methylation within mammals is found in a CG context and maintained by DNMT1, neurons contain uniquely high levels of non-CpG methylation, such that the total amounts of methylation in non-CpG contexts equals or surpasses the total amounts of methylation in CG contexts. Non-CpG methylation, unlike CpG methylation, cannot be maintained by DNMT1, and must be established by the de novo methyltransferase DNMT3A.One unique characteristic of non-CpG methylation compared to canonical CpG methylation is …

Midfoot And Ankle Movement Dysfunction In People With Diabetes Mellitus And Peripheral Neuropathy, Hyo Jung Jeong

Arts & Sciences Electronic Theses and Dissertations

People with diabetes mellitus and peripheral neuropathy (DMPN) have midfoot and ankle musculoskeletal problems, including limited joint mobility and weakness and atrophy of foot intrinsic and calf muscles. Impaired foot structures and function could lead to midfoot and ankle movement dysfunction, measured by a heel rise task. A repeated movement dysfunction during weightbearing tasks (e.g., heel rise, walking) could cause excessive stress on the plantar tissue, which is a leading cause of plantar ulceration in people with DMPN. Understanding heel rise performance and the underlying mechanisms could help prevent the sequence of events associated with plantar ulcer development in people …

Homeostatic T Cell Receptor Interactions With Self-Peptide Tune Cd4+ T Cell Function, Juliet Marie Bartleson

Arts & Sciences Electronic Theses and Dissertations

Homeostatic T Cell Receptor Interactions with Self-Peptide Tune CD4+ T Cell Function

by

Juliet Marie Bartleson

Doctor of Philosophy in Biology and Biomedical Sciences

Immunology

Washington University in St. Louis, 2021

Professor Paul M. Allen, Chair

Mature CD4+ T cells circulate throughout peripheral secondary lymphoid organs using their T cell receptor (TCR) to surveil peptide presented on major histocompatibility complex class II molecules (pMHC) in search of cognate, antigenic peptide. In the absence of an immune challenge, however, the TCR is continuously interacting with self-pMHC, which induces a relatively weak TCR signal known as tonic signaling. These homeostatic TCR:self-pMHC interactions …

Understanding The Molecular Mechanisms Of Photoferrotrophy And Phototrophic Extracellular Electron Uptake, Dinesh Gupta

Arts & Sciences Electronic Theses and Dissertations

Several anoxygenic phototrophs grow by utilizing soluble iron or insoluble mixed-valence iron minerals (such as rust) as electron donors to fix carbon dioxide using light energy, a process called photoferrotrophy. Photoferrotrophs can also use electron donors such as poised electrodes that serve as proxies for rust via phototrophic extracellular electron uptake (EEU). Despite the recognition that these two related microbial processes contribute to various biogeochemical cycles such as iron and carbon, the electron uptake mechanisms underlying photoferrotrophy and phototrophic EEU are poorly understood. To address the key knowledge gaps in our understanding of these microbial metabolisms, here we characterized Rhodopseudomonas …

Genetics Of Pediatric Musculoskeletal Disorders, Lilian Antunes

Arts & Sciences Electronic Theses and Dissertations

Pediatric musculoskeletal disorders are an extremely broad category of diseases that are often inherited. While individually rare, collectively these disorders are common, affecting around 3% of live births in the US. Despite the mounting clinical and molecular evidence for a genetic etiology, the cause for many patients with pediatric musculoskeletal disorders remain largely unknown. Major challenges in rare pediatric diseases include recruiting large numbers of patients and determining the significance and functional impacts of variants associated with disease within individuals or families. Whole exome sequencing (WES) is a powerful tool to identify coding variants that are associated with rare pediatric …

Measuring And Manipulating Tension-Dependent Behavior Of Mechanosensitive Ion Channels, Angela M. Schlegel

Arts & Sciences Electronic Theses and Dissertations

Mechanical forces play critical roles throughout the lives of all organisms and, as such, diverse arrays of mechanotransduction systems have evolved to detect and initiate responses to force. Many mechanotransduction systems consist of mechanosensitive (MS) ion channels, membrane pores that open in response to sufficient mechanical force. My dissertation focuses on both the study and application of force-dependent conformational changes of MS channels. I tested whether charged pore-lining residues R326 and D327 of the Arabidopsis thaliana mitochondrial MS channel MSL1 function in inward rectification or gating kinetics. Mutating these residues showed no effect on MSL1 rectification; however, these residues are …

Modularity Of Feedback For State-Dependent Guidance Of Navigation In Mouse Visual Cortex, Andrew M. Meier

Arts & Sciences Electronic Theses and Dissertations

Navigating through unpredictable environments requires an efficiently organized sensory system capable of adapting to behavioral demands. In the mammalian visual system, two adaptations which have arisen to meet these demands are parallel processing and top-down feedback of internally generated expectations and contextual information for adjusting responses to match the needs of the current behavioral task. Mouse visual cortex exhibits the latter of these organizing principles, like other mammals, in the form of a molecular layer (Layer 1) which receives feedback to contextually adapt sensory responses from the outside world. The first of these organizing principles, parallel processing streams, generally takes …

The Roles Of Plasmepsins Ix And X In Malaria Parasite Biology, Armiyaw Sebastian Nasamu

Arts & Sciences Electronic Theses and Dissertations

Proteases of the malaria parasite Plasmodium falciparum have been targeted for drug discovery for decades. The P. falciparum genome encodes ten aspartic proteases called plasmepsins, which are involved in diverse cellular processes. In this work we address the roles of two of these plasmepsins, plasmepsins IX and X (PM IX and X), the two least studied aspartic proteases in blood stage malaria parasites till date. We explore the essentiality of these proteases in parasite development, attempt to identify their substrates and the ability to drug them. We show that PM IX is essential for erythrocyte invasion, acting on rhoptry secretory …