Biochemistry, Biophysics, and Structural Biology Commons^™

Probing The Role Of Astrocytes In The Pathology Of Fragile X Syndrome With Human Stem Cells, Baiyan Ren

Theses & Dissertations

Fragile X syndrome (FXS) is an X-linked neurodevelopmental disorder related to intellectual disability and the most common monogenic cause of autism spectrum disorder. FXS is mainly caused by an expansion of CGG repeats in the 5’-untranslated region of fragile X mental retardation 1 (FMR1) gene, leading to the loss of expression of fragile X mental retardation protein (FMRP). Astrocytes are the most abundant glial cells in the central nervous system (CNS). Loss of FMRP in astrocytes has been found to contribute to structural and functional synaptic deficits in the Fmr1-KO mouse model. The contribution of human astrocytes, however, to the …

Functional Characterization Of Cancer-Associated Dna Polymerase Ε Variants, Stephanie R. Barbari

Theses & Dissertations

Replicative DNA polymerases ε (Polε) and δ (Polδ) achieve high fidelity DNA synthesis through a precise balance of polymerization and exonucleolytic proofreading. Errors that escape proofreading are corrected by DNA mismatch repair (MMR). Ultramutated human cancers with proficient MMR carry alterations in the exonuclease domain of Polε, which were initially predicted to abolish proofreading. However, functional studies in yeast of the most recurrent Polε-P286R variant suggested defects beyond a loss of exonuclease activity. Indeed, biochemical analysis of the yeast Polε-P286R analog revealed increased polymerization capacity in addition to decreased proofreading, which enables efficient mismatch extension and bypass of replication-blocking non-B …

Nuclear Receptor Coactivator 3 In Endoplasmic Reticulum Stress And Stress Granule Dynamics In Pancreatic Cancer, Andrew Kisling

Theses & Dissertations

Pancreatic cancer is predicted to be the second-leading cause of cancer-related deaths within the next decade. Nuclear receptor coactivator 3 (NCOA3/SRC3/AIB1) regulates an array of metabolic and signaling pathways and has been established by our group and others as a critical regulator pancreatic cancer progression and metastasis. A recent study demonstrated NCOA3 regulation by the IRE1α-XBP1 axis of the unfolded protein response (UPR), suggesting a link between NCOA3 and cellular stress management. Furthermore, NCOA3 has been shown to directly bind to a scaffolding protein of stress granules (SGs). Since SG assembly is regulated by the UPR, we hypothesized that NCOA3 …

Usp11 And Usp7 Deubiquitinases Regulate Sprtn Auto-Proteolysis And Sprtn-Mediated Dna-Protein Crosslink Repair, Megan C. Perry

Theses & Dissertations

DNA repair pathways that recognize and remove damaged DNA are vital for maintenance of genomic stability and prevention of tumorigenesis. Conversely, these pathways may be robust in tumor cells, thus diminishing the anti-cancer potential of available therapies. DNA-protein crosslinks (DPCs) are particularly deleterious DNA adducts that occur when proteins become irreversibly covalently bound to the DNA. DPCs represent a diverse group of lesions, as any protein can be crosslinked to the DNA duplex by non-specific crosslinking agents like reactive aldehydes and radiation. Additionally, functional DNA-binding proteins such as topoisomerases may become permanently crosslinked to DNA ends by abortive enzymatic processes …

A Pkcα-Mediated Growth Suppressive Mek-Erk Signaling Axis In Intestinal Epithelial Cells, Navneet Kaur

Theses & Dissertations

Members of the protein kinase C (PKC) family of serine/threonine kinases are involved in regulation of fundamental cellular functions, including proliferation, differentiation, survival, migration, and transformation. Increasing evidence points to anti-proliferative and tumor suppressive role of PKCs. Our laboratory and others have reported that the classical PKC isozyme, PKCαnegatively regulates proliferation and tumorigenesis in the intestinal epithelium. Our laboratory has further determined that PKCα signaling induces a program of cell cycle withdrawal in intestinal epithelial cells that involves downregulation of the pro-proliferative proteins, cyclin D1 and Id1, and upregulation of the cyclin dependent kinase (CDK) inhibitor, p21^Cip1. Unexpectedly, …

Molecular Mechanisms Of Aberrant Protein Glycosylation In Pancreatic Cancer Stemness And Metastasis, Frank Leon

Theses & Dissertations

A myriad of genetic and other abnormal changes underlies the aggressiveness and dissemination properties observed in pancreatic cancer (PC). Aberrant protein glycosylation is a commonly observed feature in PC. The modification of protein O-glycosylation is mediated by glycosyltransferases, which attach and sequentially elongate monosaccharides on Serine/Threonine (Ser/Thr) motifs. Aberrant glycosylation is recognized as an emerging hallmark of cancer where a disruption in normal glycosylation results in irregular O-glycans.

This dissertation research has investigated the consequences of aberrant protein glycosylation on stemness and enhancement of metastatic properties in pancreatic ductal adenocarcinoma (PDAC). Several publications have reported aberrant O-glycosylation increases in oncogenic …

Fgfr4 Glycosylation And Processing In Cholangiocarcinoma Promote Cancer Signaling, Andrew J. Phillips

Theses & Dissertations

Cholangiocarcinoma is a cancer of cholangiocytes, or epithelial cells lining the biliary tract. It is associated with a poor prognosis and additional therapeutic treatments are needed to help patients affected by this disease. Fibroblast growth factor receptor 4 (FGFR4) is receptor tyrosine kinase that is involved in various physiologic and pathologic processes. TCGA analysis of thirty different tumor types showed the highest FGFR4 mRNA levels in cholangiocarcinoma. At the protein level, FGFR4 was observed in the majority of cholangiocarcinomas screened and, higher levels were associated with a poorer prognosis. FGFR4 is an N-linked glycosylated receptor tyrosine kinase that we show …

Fibroblast Growth Factor Receptor 4 And R4-Icd Increased Proliferation, Cell Survival And Metastasis In Cholangiocarcinoma, Yamnah Hafeji

Theses & Dissertations

Fibroblast growth factor receptor 4 (FGFR4) is over-expressed in many cancers, including cholangiocarcinoma (CCA). FGFR4 is activated by fibroblast growth factor ligand 19 (FGF19) and plays a critical role in CCA progression. An intracellular cleaved product of FGFR4, referred as R4-ICD (FGFR4 intracellular domain) is also overexpressed in CCA. However, the specific role of R4-ICD in CCA is unknown. In this study, we hypothesized that FGFR4 and R4-ICD play a role in cell proliferation, cell survival and metastasis in CCA. To test this, FGFR4 and R4-ICD were cloned into a cholangiocarcinoma cell line (HuCCT-1) that does not endogenously express FGFR4. …

Dynamics Of Protein-Dna Interactions Characterized By Atomic Force Microscopy, Yaqing Wang

Theses & Dissertations

This thesis describes the nanoscale studies of protein-DNA interactions with different complexities using atomic force microscopy (AFM). One of the systems deals with DNA replication rescue. To maintain the genetic integrity, replication machinery needs to minimize the error rate, repair the damages, and restart the stalled replication caused by the attacks from the environment and inside the cell. The stalled replication rescue is orchestrated by a series of proteins, for example, the DNA helicases PriA and RecG and the ssDNA binding protein (SSB).

We demonstrated that SSB stimulates the restart process in two aspects. First, SSB facilitates the binding of …

Mucin And Splice Variant Profiles Of Pancreatic Adenocarcinoma Predict Patient Survival And Subtyping, Christopher M. Thompson

Theses & Dissertations

PDAC is a pancreatic epithelial malignancy and demonstrates aggressive progression and bleak patient prognosis. Despite decades of research, the evolution of novel diagnostics and intervention modalities for PDAC is stagnant. This dissertation explores the characteristic aberrant and elevated expression of mucins in PDAC. Beginning with the hypothesis that mucins are associated with disease aggressiveness, analysis of PDAC patient survival in TCGA revealed no associations between single mucin expression and patient survival. This led to the underlying issue of PDAC tumor cellularity since this disease demonstrates variability in the proportion of cancer cells within the tumor. Tumor purity assessed with the …

Design, Synthesis And Evaluation Of Novel Inhibitors Of Type 5 And 10 17Β-Hydroxysteroid Dehydrogenases, Ahmed Morsy

Theses & Dissertations

17β-Hydroxysteroid dehydrogenases (17β-HSDs) are essential enzymes in steroid metabolism. More and more evidence points to the pivotal contributions of these enzymes in various other metabolic pathways. Therefore, the latest research results give new insights into the complex metabolic interconnectivity of the 17β-HSDs with human diseases. This dissertation focuses on the metabolic activities of type 5 and 10 17β-HSDs. More specifically, regarding 17β-HSD5 contributions to the progression of prostate cancer (PCa) and 17β-HSD10 aggravation of amyloid-beta (Aβ)-induced toxicity in Alzheimer's disease (AD).

The second leading cause of cancer-related death in males is PCa, with the highest incidence rate of all cancers …

Development Of In-Silico Pipelines For Identification And Characterization Of Biomarker Panels And Therapeutic Interventions In Gastro-Intestinal (Gi) Cancers, Pranita Atri

Theses & Dissertations

Gastro-intestinal (GI) malignancies, including gastric, colorectal, and pancreatic cancers, have maintained their high overall mortality due to a lack of prognostic and diagnostic biomarkers and potential therapeutic modalities. While efforts have been made to improve both early detection and therapeutic interventions in these cancers, failure of conventional approaches have proven to be a big challenge, and alternate approaches are needed. Computational biology approaches owing to lesser time and more per target success rate offer a unique solution here. The current study explored the use of computational biology techniques to study the various aspects relating to GI malignancies. First, we sought …

Role Of Endocytic Machinery Regulators In Egfr Traffic And Viral Entry, Insha Mushtaq

Theses & Dissertations

STUDY 1: Role of endocytic regulator EHD1 and its binding partner RUSC2 in EGFR traffic

Abstract

Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While post activation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/pre-activation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular …

Secreted Mucin 5ac-Mediated Epithelial And Stromal Modulations Augment Pancreatic Cancer Aggressiveness, Koelina Ganguly

Theses & Dissertations

The mucosal layer that shields the epithelium of the body cavities is made up of high molecular weight, heavily glycosylated proteins called mucins that are broadly categorized into transmembrane and secreted members. Aberrant expression of secreted mucin MUC5AC has been implicated in lung, stomach, and colon cancer pathologies. MUC5AC is expressed de novo in the pancreas upon oncogenic insult, and its abundance in pancreatic tumor and circulation correlates to disease progression. However, few studies have explored beyond the diagnostic and prognostic significance of MUC5AC in pancreatic cancer (PC).

In this dissertation, we sought to investigate the mechanistic contribution of MUC5AC …