Medicine and Health Sciences Commons^™

Genetic Risk Factors For Neurodevelopmental Disorders: Insights From Hipsc-Cerebral Organoids, Michelle L. Wegscheid

Arts & Sciences Electronic Theses and Dissertations

Neurofibromatosis type 1 (NF1) is a common neurodevelopmental disorder (NDD) characterized by remarkable phenotypic variability, where affected children manifest a spectrum of central nervous system (CNS) abnormalities, including brain tumors, impairments in attention, behavior, learning disabilities, and an increased incidence of autism spectrum disorder (ASD). A significant barrier to the implementation of precision medicine strategies for children with NF1 is a lack of prognostic risk factors to guide clinical management. However, emerging population-based genotype-phenotype association studies have suggested that the germline NF1 gene mutation may represent one clinically actionable risk factor for NF1-associated neurodevelopmental abnormalities. As a critical step in …

Exploring Β-Cell Function And Heterogeneity In Obese Sm/J Mice, Mario Alejandro Miranda

Arts & Sciences Electronic Theses and Dissertations

Pancreatic β-cells perform glucose-stimulated insulin secretion, a process required to maintain systemic glucose homeostasis. Obesity promotes glycemic and inflammatory stress, causing β-cell death and dysfunction, resulting in diabetes. Efforts to improve β-cell function in obesity have been hampered by observations that β-cells are highly heterogeneous, varying in morphology, function, and gene expression. There is great need to understand the breadth of β-cell heterogeneity in health and obesity to improve diabetic therapies.High fat-fed SM/J mice spontaneously transition from hyperglycemic-obese to normoglycemic-obese with age, providing a unique opportunity to study β-cell adaptation. Here, we show that as they resolve hyperglycemia, obese SM/J …

Metabolic Control And Immune Barriers Of Hematopoietic Stem Cells, Hannah Pizzato

Arts & Sciences Electronic Theses and Dissertations

Hematopoietic stem cells (HSCs) have the unique ability to self-renew for life, to differentiate into mature blood lineages, and to readily engraft upon intravenous transplantation. As such, they are the only types of stem cells in routine clinical use. Understanding HSCs and hematopoietic development can provide many lessons for other types of stem cells as they near clinical utility. Through bone marrow transplantation, it was discovered that cells exist with regenerative potential. This led to the search to purify these cells and to determine the function of other hematopoietic cells. By isolating and transplanting cells expressing different combinations of surface …

Exploring The Intrinsic And Extrinsic Factors That Regulate Breast Cancer Cell Dormancy, Qihao Ren

Arts & Sciences Electronic Theses and Dissertations

Breast cancer can recur in patients months to decades after initial diagnosis and treatment. There is mounting evidence that dormant breast disseminated tumor cells (DTCs) exist in distant organs, whose reactivation results in cancer recurrence. However, the mechanisms that control tumor cell dormancy remain poorly understood, making it difficult to predict which patients will recur and develop cancer recurrence. Unfortunately, the extreme rarity of dormant DTCs has been the major obstacle to their study. To overcome this challenge, we developed an efficient system to isolate and study rare dormant tumor cells from metastatic organs. Using this system and single cell …

Discovery Of Sex Differences In Response To P53 Loss And Gain-Of-Function In Glioblastoma, Nathan Cuyle Rockwell

Arts & Sciences Electronic Theses and Dissertations

The tumor suppressor TP53 (p53) is the most frequently mutated gene in cancer and among the most mutated genes in brain cancer. Functionally, p53 is a transcription factor that, when activated by an array of stress stimuli, regulates a complex transcriptional program that contributes to a variety of antiproliferative pathways. The loss of p53 function (LOF), either through mutation, deletion, or inhibition by alterations in the proteins that regulate p53, removes an essential barrier to the unfettered proliferation and genomic instability that drive transformation. Unlike most tumor suppressors, many p53 mutations are missense mutations that lead to stable expression of …

Uncovering A Myc-Driven Tumor-Suppressive Program In Proliferating Lymphocytes, Elena Tonc

Arts & Sciences Electronic Theses and Dissertations

Rapid cell proliferation is a hallmark feature of adaptive immune cells lymphocytes. It is essential for the establishment of diverse antigen receptor repertoires and amplification of antigen-specific immune responses. While such proliferation is beneficial for host protection from infections and cancers, it inevitably elevates the risk of oncogenic transformation. In developing and germinal center B lymphocytes, the risk is further increased by endogenous, genomic insults due to antigen receptor rearrangements and somatic mutations, with which expression of the proto-oncogene c-MYC is closely associated. Nonetheless, frequencies of cancers originated from B lymphocytes are relatively low, suggesting that they are protected from …

Transcriptional Control Of Dendritic Cell Function And Development, David Alexander Anderson Iii

Arts & Sciences Electronic Theses and Dissertations

Dendritic cells (DCs) are innate immune cells of the myeloid lineage that are specialized at pathogen recognition, cytokine production, and antigen presentation. Their functions and developmental pathways are largely conserved between mice and humans and mice. The DC lineage is composed of two major subsets, known as plasmacytoid DCs (pDCs) and classical DCs (cDCs). Research conducted to date suggests that the function of pDCs, limited to viral antigen recognition and type I interferon production, can be compensated by other immune cell lineages. On the other hand, there is a consensus that diversified subsets cDCs in mice and humans are essential …

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 …

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 …

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 …

Investigating Biological Mechanisms Of Radiation Resistance In Advanced Stage Cervical Cancer, Fiona Ruiz

Arts & Sciences Electronic Theses and Dissertations

The current standard of care treatment for locally advanced cervical cancer is curative intent pelvic radiation with concurrently administered platinum chemotherapy (CRT). This treatment strategy is effective for many patients, but 33-50% of patients treated with CRT develop disease recurrence. Metastatic and recurrent cervical cancer is an incurable condition, and many of the currently available treatments are associated with significant morbidity and mortality. Identifying these patients upfront is a challenge that clinicians face when developing treatment strategies. Previous studies used to catalog the genomic and transcriptomic landscape of cervical cancer lacked high quality corresponding clinical follow up data for patients, …

T Cell Immunity In Pancreatic Cancer Is Undermined By Dendritic Cell Dysfunction, Samarth Hegde

Arts & Sciences Electronic Theses and Dissertations

Pancreatic cancer carries a dismal prognosis, and desperately needs viable therapeutic interventions beyond chemo-radiation. T cell-dependent immunotherapies have shown great promise in several tumor types, but have not been effective for the vast majority of pancreatic cancer patients. This is, in part, due to our limited understanding of how antigenicity of pancreatic lesions is recognized, and how adaptive immunity is overcome in this disease. We sought to study tumor-immune interactions and identify mechanisms for this immune-failure using several spontaneous and unperturbed mouse models of pancreatic adenocarcinoma. We found that early pancreatic lesions fail to elicit tumor-limiting CD4+ TH1 and CD8+ …

Mesothelium-Derived Factors Shape Tissue Resident Macrophage, Chin-Wen Lai

Arts & Sciences Electronic Theses and Dissertations

The studies outlined in this thesis provide several new insights into Msln-related pathways necessary for peritoneal immune responses and mucosal repair. We found that Msln and its binding partner mucin 16 from mesothelium influenced peritoneal and pleural macrophage differentiation. We found that Msln was required for proper tissue repair after colonic biopsy injury and was required for maximal polyp growth in APCMin/+ mice. Overall, this work describes mesothelial and epithelial-derived factors that are important for tissue resident macrophage differentiation and wound repair after colonic mucosal injury. Understanding the complex interactions between stromal cells and immune cells will lead to better …

Understanding The Transcriptional Mechanisms Underlying Dendritic Cell Development, Prachi Bagadia

Arts & Sciences Electronic Theses and Dissertations

Dendritic cells (DCs) comprise an important immune lineage that plays a critical role in initiating and sustaining the proper immune response. They can be divided into two distinct branches, classical/conventional DCs (cDCs) or plasmacytoid DCs (pDCs). cDCs can further be classified as cDC1 or cDC2. Each DC subset exerts unique functions in vivo and are necessary for a complete immune response. The precise transcriptional programs underlying DC specification and commitment remain unclear. cDC1, cDC2, and pDC all arise from the common DC progenitor (CDP) in the bone marrow. How the CDP gives rise to all three DC subsets in an …

Exploring Infant Leukemia Through Exome Sequencing And An In Vitro Model Of Hematopoietic Development, Mark Cannon Valentine

Arts & Sciences Electronic Theses and Dissertations

Cancer is a heterogeneous disease with myriad causes and outcomes. Many of the cancers that occur in adult populations have become increasingly well characterized with the advent of affordable high-throughput sequencing. These studies have revealed that cancer is largely a disease of somatic mutation in the adult population. In strong contrast to this, childhood cancers have an exceedingly low rate of somatic mutation. At the extreme end of this spectrum is Infant Leukemia (IL). Sequencing of IL has revealed that these tumors frequently have one or fewer somatic SNP. In the absence of a somatic explanation for IL, many other …

Dissemination Of The Apicomplexan Parasite, Toxoplasma Gondii, Lisa L. Drewry

Arts & Sciences Electronic Theses and Dissertations

The parasitic protist Toxoplasma gondii is a common pathogen of rodents and felines that also infects humans. The most severe clinical manifestations of toxoplasmosis in humans derive from the systemic dissemination of T. gondii, during which the parasite penetrates biological barriers and accesses protected host compartments such as the central nervous system. T. gondii dissemination is enabled by the intrinsic gliding motility of extracellular parasites, which allows for travel to new host cells and tissues, and also powers the invasion of diverse host cells including migratory leukocytes. Dissemination is further advanced when migrating infected leukocytes shuttle intracellular parasites to new …

Circadian Regulation Of Temozolomide Sensitivity In Glioblastoma, Emily A. Slat

Arts & Sciences Electronic Theses and Dissertations

The safety and efficacy of multiple cancer chemotherapeutics can vary as a function of when during the day they are delivered. This study aimed to improve the treatment of glioblastoma multiforme (GBM), the most common brain cancer, by testing the efficacy of the DNA alkylator Temozolomide (TMZ) on GBM in vitro and in vivo as a function of time of day. We found cell-intrinsic, daily rhythms in susceptibility of GBM tumor cells (mouse astrocytes deficient in NF1 and p53 signaling) to TMZ in vitro. The greatest TMZ-induced DNA damage response, activation of apoptosis and growth inhibition, occurred near the peak …

The Ugly Sequestosome1:The Role Of P62/Sqstm1 In Autophagy And Multisystem Proteinopathy, Eugene Lee

Arts & Sciences Electronic Theses and Dissertations

Multisystem proteinopathy (MSP) defines a spectrum of degenerative diseases unified by TDP-43 pathology that affect muscle, brain and bone. Mutations in several proteins (VCP, p62/SQSTM1, HNRNPA2B1, HNRNPA1) can all cause MSP via impairments in autophagic protein degradation (VCP and SQSTM1) or RNA granule dynamics (HNRNPA2B1 and HNRNPA1). Phenotypically, MSP mutations lead to variable penetrance of several phenotypes: Paget’s disease of the bone (PDB), rimmed vacuolar inclusion body myopathy (RV-IBM), amyotrophic lateral sclerosis (ALS) or frontotemporal dementia (FTD). However, how a same mutation of a protein can develop different diseases remains unclear. Understanding of p62/SQSTM1 (SQSTM1) function is critical to answer …

Tumors Interrupt Irf8-Mediated Dendritic Cell Development To Overcome Immune Surveillance, Melissa Ann Meyer

Arts & Sciences Electronic Theses and Dissertations

Tumors employ multiple mechanisms to evade immune surveillance. One mechanism is tumor-induced myelopoiesis, which expands immune suppressive granulocytes and monocytes to create a protective tumor niche shielding even antigenic tumors. As myeloid cells and immune-stimulatory conventional dendritic cells (cDCs) are derived from the same progenitors, it is logical that tumor-induced myelopoiesis might also impact cDC development. The cDC subset cDC1 is marked by CD141 in humans and CD103 or CD8α in mice. cDC1s act by cross presenting antigen and activating CD8+ T cells. Given these functions, CD103+ cDC1s can support anti-tumor CD8+ T cell responses. However, CD103+ cDC1 numbers are …

Characterization And Function Of Islet Antigen Presenting Cells During Nod Diabetes, Stephen Thomas Ferris

Arts & Sciences Electronic Theses and Dissertations

Here we characterized the initial antigen presenting cells (APCs) within the islet of Langerhans to ascertain their identity and functional role as it pertains to autoimmune diabetes. The activation of the adaptive immune system is induced by the innate immune system, and more specifically APCs. Therefore, it is crucial to identify the APCs that are initiating T1D in order to elucidate the break in tolerance and intervene in order to inhibit progression. We have found that there is a resident macrophage that is present in all strains of mice. This islet macrophage has a distinct transcriptional profile that is unique …

Mitochondrial Dynamics Controls T Cell Fate Through Metabolic Programming, Michael Buck

Arts & Sciences Electronic Theses and Dissertations

Activated effector T (TE) cells augment anabolic pathways of metabolism, such as aerobic glycolysis, while memory T (TM) cells engage catabolic pathways, like fatty acid oxidation (FAO). However, signals that drive these differences remain unclear. Mitochondria are metabolic organelles that actively transform their ultrastructure. Therefore, we questioned whether mitochondrial dynamics controls T cell metabolism. We show that TE cells have punctate mitochondria, while TM cells maintain fused networks. The fusion protein Opa1 is required for TM, but not TE cells after infection, and enforcing fusion in TE cells imposes TM cell characteristics and enhances antitumor function. Our data suggest that, …