Medicine and Health Sciences Commons^™

Structural Characterization Of The C-Terminus Of The Cochlear Motor Protein Prestin: Intrinsic Disorder Linked To Voltage Sensor Function, Michael S. Podgorski

Theses and Dissertations (ETD)

The sensitivity of mammalian hearing relies upon the ability to amplify sound. Outer hair cells (OHCs) in the cochlea have motile properties that support this function. The motor protein called prestin resides in the lateral wall of the OHCs. Prestin undergoes voltage-dependent conformational changes, which correlates to the movement of charge through the membrane or non-linear capacitance (NLC). This property underlies OHC electromotility. A mechanistic understanding of prestin’s function remains unknown. Previous research has tied prestin’s C-terminus (residues 499-799) to the voltage-dependent events that occur in the membrane. The folding and biochemical properties of prestin’s C-terminus were characterized. This information …

Identification Of The Downstream Effector Genes Involved In Hoxb4-Induced Expansion Of Hematopoietic Progenitor Cells, Jie Jiang

Theses and Dissertations (ETD)

Overexpression of HOXB4, a member of Homeobox transcription factor family, promotes expansion of hematopoietic stem and progenitor cells bothin vivo and in vitro. However, the molecular mechanisms underlying this effect are not well understood. In order to identify direct target genes of HOXB4 in primary murine hematopoietice progenitor cells, we induced HOXB4 function in lineage-negative, murine bone marrow cells, using a tamoxifen-inducibleHOXB4-ER^T2fusion protein. Seventy seven genes with differentially changed expression in early response to HOXB4 have been identified as candidate target genes. Among them, we show that Hemogen (Hemgn), encoding a nuclear protein specifically …

Contribution Of Organic Cation Transporter 2 (Oct2) To Cisplatin-Induced Nephrotoxicity, Kelly K. Filipski

Theses and Dissertations (ETD)

Cisplatin is the most widely used anticancer agent; however, the cellular pharmacokinetics are poorly understood. Cisplatin is predominantly eliminated through the urine via active secretion and is associated with nephrotoxicity. Currently, prehydration therapy is employed to prevent toxic renal side effects; however it has not been completely ameliorated. The studies described herein aim to determine the mechanism in which cisplatin enters the kidney cell from the blood and how it is subsequently secreted into the urine. Organic cation transporter 2 (OCT2) and ABCC2 are highly expressed in the kidney on the basolateral and apical membrane, respectively. We determined the contribution …

Regulation Of Pyruvate Dehydrogenase Kinase 4 By Thyroid Hormone / Role Of Peroxisome Proliferator Activated Receptor Gamma Coactivator-1 Alpha And Ccaat Enhancer Binding Protein, Ramy Naguib Attia

Theses and Dissertations (ETD)

Pyruvate dehydrogenase kinase 4 (PDK4) regulates pyruvate oxidation through the phosphorylation and inhibition of the pyruvate dehydrogenase complex (PDC). The PDC catalyzes the conversion of pyruvate to acetyl-CoA and it is an important control point in glucose and pyruvate metabolism. Previous studies had reported that PDK4 gene expression is induced by thyroid hormone (T3). These studies did not investigate the mechanisms by which T3 regulated PDK4 gene expression. I have examined the role of the thyroid hormone receptor (TR), transcriptional coactivators especially the peroxisome proliferator activated receptor gamma coactivator-1 (PGC-1α) and other transcription factors that act as accessory factors in …

Studying The Specificity Of Hpxr Antagonists Using A Panel Of Cell-Based Assays, Fang Lei

Theses and Dissertations (ETD)

The pregnane X receptor (PXR or SXR; NR1I2) is a member of the nuclear receptor superfamily. It activates the transcription of a large network of genes including cytochrome P450 (CYP) and Mdr1 which play critical roles in chemicals metabolism and transportation. Induction of CYPs contributes to adverse drug-drug interactions. Non-toxic, PXR-specific antagonists will be valuable in attenuating the adverse drug-drug interaction which is the cause of many treatment failures in clinic. However, few hPXR antagonists were reported particularly the specific ones. In this thesis a reporter gene assay was used to study the specificity of hPXR antagonists from a panel …

Insights Into Btb-Cul3 Ubiquitin Ligases From The Structures Of Spop-Substrate Complexes, Min Zhuang

Theses and Dissertations (ETD)

Cullin-Ring ubiquitin ligases (CRLs) are E3 complexes that specifically recognize substrates through substrate adaptors. In the largest CRL subfamily, Cul3 binds a BTB domain, and a protein-interaction domain such as MATH recruits substrates for ubiquitination. Here we present biochemical and structural analyses of the MATH and BTB domain containing protein, SPOP, which regulates diverse signaling pathways. First, we identified a conserved SPOP Binding Consensus (SBC) motif in the transcriptional regulator Ci, the protein phosphatase Puc, and the chromatin component MacroH2A. The SBC motif specifically binds the MATH domain of SPOP, and is required for Puc ubiquitination in vitro and in …

Structural And Kinetics Studies Of The Enzyme Dihydropteroate Synthase And The Implications For Antibiotic Resistance, Katherine A. Ayers

Theses and Dissertations (ETD)

The goal of this study is to develop small molecule inhibitors of DHPS for the treatment of a variety of infectious diseases. According to the World Health Organization (WHO), infectious diseases kill more than 13 million people worldwide every year making it the second leading cause of death behind cardiovascular disease. The sulfonamide class of drugs has been in use since the 1930’s to treat many infectious agents and act by targeting the enzyme dihydropteroate synthase (DHPS) of the prokaryotic and lower eukaryotic folate pathway.

DHPS is an ideal drug target because humans do not synthesize folate de novo and …

Effects Of Microgravity On Cancer Stem Cells Cultured In A Nasa Developed Bioreactor: Chemotherapeutic Implications., Sarah Elizabeth Daron Kelly

Theses, Dissertations and Capstones

The purpose of this study was to investigate the effects of simulated microgravity on cancer cell growth. Simulated microgravity is a condition in which cells are in constant free-fall and in which they are able to grow suspended without the shear and stress. Microgravity allows for important insights into the cellular mechanism and may be key in understanding why some cells thrive in this condition and others go into apoptosis. Cancer stem cells (CSCs) are considered a subset of the bulk tumor responsible for initiating and maintaining cancer. SAOS-2 is a human bone cancer cell line which consists of a …

Deferasirox Decreases Age-Associated Iron Accumulation In The Aging F344bn Rat Heart, Ravi K. Arvapalli

Theses, Dissertations and Capstones

It is thought that aging in rats and humans is associated with increases in iron accumulation and these increases in iron may be associated with increased cellular apoptosis. Here we examine the relationship between cardiac iron levels and cardiomyocyte apoptosis in aged F344BN rats which were treated with an oral iron chelator (Deferasirox; 100mg/kg body. weight/day) for 6 months. Compared with 6- month controls, the levels of cardiac iron, cardiac apoptosis, FLC and DMT-1 were higher in 33-month hearts. Deferasirox treatment for six months decreased cardiac iron and this was associated with decreases in the number of apoptotic cardiac myocytes. …