Molecular Biology Commons^™

Development Of Novel Methods To Study Host-Microbe Interactions In The Larval Zebrafish Gastrointestinal Tract, Anh K. Trinh Nguyen

Dissertations & Theses (Open Access)

The dynamic nature and inaccessible location of the intestine pose significant challenges to the study of intestinal physiology and pathology. Zebrafish larvae, possessing optical transparency and genetic tractability, offer an accessible and clinically relevant model for investigating dynamic events in the intestine via time-lapse imaging. In the first part of this work, I discuss our efforts to optimize the parameters of a foodborne infection assay using paramecia as a vehicle. This method provides an effective, high-throughput alternative to infection via immersion or oral gavage, and replicates the most common route of transmission of gastrointestinal (GI) infection in humans. The foodborne …

The Role Of The Hypoxia-Inducible Factor 2 In Pancreatic Cancer: Mechanisms Of Tumor Immunosuppression And Intestinal Radioprotection, Carolina Garcia Garcia

Dissertations & Theses (Open Access)

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with dismal prognosis. The only curative option for patients is surgery, but over 80% of patients are not surgical candidates. Unfortunately, PDAC is resistant to the three remaining options. PDAC is characterized by a profoundly hypoxic and immunosuppressive stroma, which contributes to its therapeutic recalcitrance. Alpha-smooth muscle actin+ (αSMA+) cancer-associated fibroblasts (CAFs) are the most abundant stromal component, as well as mediators of stromal deposition. The hypoxia-inducible factors (HIF1 and HIF2) coordinate responses to hypoxia, yet, despite their known association to poor patient outcomes, their functions within the PDAC tumor microenvironment (TME) …

Investigating The Role Of Quaking In Antigen Uptake And Cross-Presentation By Dendritic Cells, Yating Li

Dissertations & Theses (Open Access)

Dendritic cells (DCs) are considered the most potent antigen presenting cells (APC) due to their superior capability of cross-presenting exogenous antigens to CD8⁺ T cell for strong adaptive immune responses. They internalize foreign antigens by phagocytosis, endocytosis or macropinocytosis, which are then processed in endosomal compartments and loaded onto MHC Class I molecules. However, the molecular mechanisms regulating exogenous antigen uptake and cross-presentation by DCs are not fully understood.

In this study, we discovered that an RNA-binding protein, Quaking (QKI) plays a pivotal role in antigen uptake by DCs. Our previous studies in neural stem cells and microglia have …

Effects Of Penfluridol On Integrin-Fak Signaling And Tumor Cell Killing In Combination With Oncolytic Hsv In Glioblastoma, Mitra Nair

Dissertations & Theses (Open Access)

Integrins are known to play an important role in activating multiple intracellular pathways, one of which is focal adhesion kinase (FAK). Phosphorylation of FAK can lead to the activation of various downstream signaling pathways that can increase tumor cell growth and proliferation, making it an ideal target for cancer therapeutics. Due to the fact that many FAK inhibitors are limited in their penetration of the blood brain barrier, we investigated the use of Penfluridol, an antipsychotic drug known to attenuate integrin expression at a transcriptional level, in combination with oncolytic herpes simplex I virus (oHSV) in a glioblastoma model. We …

Loss Of Caspase-8 Function In Combination With Smac Mimetic Treatment Sensitizes Head And Neck Squamous Carcinoma To Radiation Through Induction Of Necroptosis., Burak Uzunparmak

Dissertations & Theses (Open Access)

Caspase-8 (CASP8) is one of the most frequently mutated genes in Head and Neck Squamous Carcinomas (HNSCC), and mutations of CASP8 are associated with poor overall survival. The distribution of these mutations in HNSCC suggests that they are likely to be inactivating. Inhibition of CASP8 has been reported to sensitize cancer cells to necroptosis, a unique cell death mechanism. Here, we evaluated how CASP8 regulates necroptosis in HSNCC using cell line models and syngeneic mouse xenografts. In vitro, knockdown of CASP8 rendered HNSCCs susceptible to necroptosis induced by a second mitochondria-derived activator of caspase (SMAC) mimetic, Birinapant, when combined …

Preeclampsia: The Roles Of Acute Inflammation And Intrauterine Stress, Nicholas Parchim

Dissertations & Theses (Open Access)

Preeclampsia (PE) is a severe, acute disease of pregnancy affecting approximately 8% of pregnant women after week 20 of gestation. PE is characterized by hypertension and renal damage reflected by proteinuria and has significant morbidity to both mother and fetus. Maternal symptoms range from headaches, nausea, edema, to visual changes, but once maternal symptoms present, damage to the fetus has begun. Mothers who progress untreated through the disease can also experience a condition called eclampsia characterized by seizure, coma, and, ultimately, death. PE-affected newborns experience features similar to prematurity—abnormal lung and renal development, intrauterine growth retardation (IUGR), and, possibly, fetal …

Preventing Thymus Involution In K5.Cyclin D1 Transgenic Mice Sustains The Naïve T Cell Compartment With Age, Michelle L. Bolner

Dissertations & Theses (Open Access)

The thymus maintains T cell receptor (TCR) repertoire diversity through perpetual release of self-MHC restricted naive T cells. However, thymus involution during the aging process reduces naïve T cell output, leading to defective immune responsiveness to newly encountered antigens. We have found that early thymus involution precipitates the age-associated shift favoring memory T cell dominancy in young control mice. Furthermore, we have shown that age-related thymus involution is prevented in mice expressing a keratin 5 promoter-driven Cyclin D1 (K5.D1) transgene in thymic epithelial cells (TECs). Thymopoiesis occurs normally in K5.D1 transgenic thymi and sustains T cell output to prevent the …

The Effect Of Activation Induced Cytidine Deaminase Phosphorylation And Herpes Virus Uracil Dna Glycosylase On Antibody Diversification, Marc Macaluso

Dissertations & Theses (Open Access)

Activation-induced cytidine deaminase (AID) is a mutagenic enzyme that is expressed in mammalian B-cells and initiates the antibody diversification processes of somatic hypermuntation (SHM) and isotype class switch recombination (CSR). AID is targeted to the immunoglobulin gene locus where it deaminates cytosines to generate uracil residues in DNA. This generates guanine-uracil (U:G) mismatch lesion which are recognized by uracil DNA glycosylase (UNG), a DNA repair enzyme that removes uracil from DNA and triggers downstream repair of the lesion. While UNG is a ubiquitously expressed DNA repair enzyme, its recognition and removal of AID introduced uracils is essential in both SHM …

Regulation Of Toxin Synthesis By Clostridium Difficile, Charles Darkoh

Dissertations & Theses (Open Access)

Clostridium difficile is the leading definable cause of nosocomial diarrhea worldwide due to its virulence, multi-drug resistance, spore-forming ability, and environmental persistence. The incidence of C. difficile infection (CDI) has been increasing exponentially in the last decade. Virulent strains of C. difficile produce either toxin A and/or toxin B, which are essential for the pathogenesis of this bacterium. Current methods for diagnosing CDI are mostly qualitative tests that detect the bacterium, the toxins, or the toxin genes. These methods do not differentiate virulent C. difficile strains that produce active toxins from non-virulent strains that do not produce toxins or produce …