Biochemistry, Biophysics, and Structural Biology Commons^™

Chemical Damage To Mrna And Its Impact On Ribosome Quality-Control And Stress-Response Pathways In Eukaryotic Cells, Liewei Yan

Arts & Sciences Electronic Theses and Dissertations

Ribosome often faces defective adducts that disrupt its movement along the mRNA template. These adducts are primarily caused by chemical damage to mRNA and are highly detrimental to the decoding process on the ribosome. Hence, unless dealt with, chemical damage to RNA has been hypothesized to lead to the production of toxic protein products. Even more detrimental is the ability of damaged mRNA to drastically affect ribosome homeostasis through stalling. This in turn would lead to greatly diminished translation capacity of cells. Therefore, the inability of cells to recognize and resolve translational-stalling events is detrimental to proteostasis and could even …

Single-Cell Resolution Mechanistic Analyses Of Direct Lineage Reprogramming, Chuner Guo

Arts & Sciences Electronic Theses and Dissertations

End-stage organ failures remain a clinical challenge with an unmet need for medical therapies, with transplantation often being the only curative option. Despite advances in transplantation outcomes, organ shortage continues to limit the availability of cures to patients in need. The direct lineage reprogramming of one cell type to another is a promising avenue for therapy with the following advantages: (1) patient-specific cell sources, (2) direct conversion without reverting to pluripotency and the associated risk of teratoma formation, and (3) utilization of the cell type responsible for fibrotic scar formation for the engineering towards the desired cell fate. Nonetheless, many …

Rhoa Mediated Juxtacrine Regulation Of Glucagon Secretion, Yong Hee Chung

Arts & Sciences Electronic Theses and Dissertations

Glucagon is secreted from pancreatic islet alpha-cells in response to hypoglycemia. The regulation of this secretion likely involves multiple interacting molecular pathways. There are three general types of proposed models for glucose-dependent regulation of glucagon secretion: direct regulation by glucose mediated modulation of cell electrophysiology, paracrine regulation by other endocrine cell types within the islets of Langerhans, and juxtacrine regulation by surface protein interactions from neighboring beta-cells. This work is focused on one pathway of juxtacrine regulation that occurs through signaling from EphA4 receptors on the surface of α-cells upon interaction with ephrin-A5 ligands on the surface of beta-cells. In …

The Role Of Cd53 In Hematopoietic Development, Stress, And Malignancy, Zev Joshua Greenberg

Arts & Sciences Electronic Theses and Dissertations

For a cell to function properly, it must be able to interact with and respond to environmental cues; however, expression of surface molecules, proteins, and receptors is not always sufficient to execute a cellular response. Proper organization of the plasma membrane is necessary to facilitate these highly regulated protein interactions, such that a cell can respond to stressors, growth factors, and other signaling molecules. Tetraspanins are a family of transmembrane proteins which help correctly orient surface molecules on the cell membrane, often through tetraspanin enriched microdomains, a membrane structure similar to lipid rafts. As a family, tetraspanins are known to …

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 …

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 …

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 …