Medicine and Health Sciences Commons^™

The Effects Of Pten Deletion On Cell Size And Plasticity In The Hippocampus, Margaret Sperow

Theses and Dissertations (ETD)

The tumor suppressor phosphatase and tensin homolog (PTEN) is the central negative regulator of the phosphatidylinositol 3-kinase (PI3K) -signaling pathway, which mediates diverse processes in various tissues. In the nervous system, the PI3K pathway modulates proliferation, migration, cellular size and synaptic transmission and plasticity. Neurologic abnormalities such as autism, seizures, and ataxia are associated with inherited PTEN mutations. Yet, how PTEN loss contributes to neurologic dysfunction remains unknown. PTEN loss during early development is associated with extensive deficits in neuronal migration and substantial hypotrophy of neurons and synaptic densities. However, whether its effect on synaptic transmission and plasticity is direct …

Characterization Of The Mechanism Of Pparγ-Mediated Neointima Formation In Rodents, Ryoko Tsukahara

Theses and Dissertations (ETD)

Lysophosphatidic acid (LPA) and its ether analog alkyl glycerophosphate (AGP) elicit arterial wall remodeling when applied intralumenally into the uninjured carotid artery. LPA is the ligand of eight GPCRs and the peroxisome proliferator-activated receptor γ (PPARγ). We pursued a gene knockout strategy to identify the LPA receptor subtypes necessary for the neointimal response in a non-injury model of carotid remodeling and also compared the effects of AGP and the PPARγ agonist rosiglitazone (ROSI) on balloon injury-elicited neointima development. In the balloon injury model AGP significantly increased neointima; however, rosiglitazone application attenuated it. AGP and ROSI were also applied intralumenally for …

Characterization Of The Key Mouse Cochlear Developmental Genes For Auditory Hair Cell Regeneration, Zhiyong Liu

Theses and Dissertations (ETD)

Mammalian inner ear cochlear auditory hair cells (HCs) and adjacent supporting cells (SCs) are believed to derive from the same progenitors during development. However, unlike SCs of nonmammalian vertebrates, mammalian cochlear SCs cannot be converted into functional hair cells (HCs) after damage, thus leading to permanent deafness. To entitle mammals with the ability to restore hearing capacity after HC damage, we first achieved proliferation of SCs by acute ablation of p27 or Sox2. Secondly, we overactivated Notch1 signaling in the mouse inner ear at different developmental stages, and found that the ability of Notch signaling in generating new HCs declines …

Autoimmune Consequences Of Histone Deimination During Neutrophil Activation, Nishant Dwivedi

Theses and Dissertations (ETD)

Tolerance blocks the expression of autoantibodies, whereas autoimmunity promotes it. How tolerance breaks and autoantibody production begins, thus, are crucial questions for the understanding and treatment of autoimmune diseases. Evidence implicates cell death and autoantigen modifications in the initiation of autoimmune reactions. One form of neutrophil cell death deserves attention because it occurs as a consequence of neutrophil activation, requires the post-translational modification of histones and results in the extracellular release of chromatin. The extracellular chromatin incorporates histones in which arginines have been converted to citrullines by peptidylarginine deiminase IV (PAD4) creating structures that capture or "trap" bacterial pathogens. Neutrophil …

Testing Whether Mrp4 (A Camp Efflux Pump) And The Beta 2 Andrenergic Receptor (An Upstream Regulator Of Camp Signaling Pathways, Praveen Kumar Potukuchi

Theses and Dissertations (ETD)

Background and Aim: MRP4/ABCC4 is an ABC transporter that can efflux the second-messenger, cAMP, from cells. MRP4 has a PDZ interacting motif at its carboxy terminal end through which it binds to scaffolding proteins NHERF1 and PDZK1. Previous studies have shown that PDZK1 serves as a scaffold physically coupling MRP4 with the cystic fibrosis transmembrane conductance regulator (CFTR). This protein complex functionally couples cAMP regulation of CFTR function with MRP4 cAMP transporter activity [Li, C., et al., Spatiotemporal coupling of cAMP transporter to CFTR chloride channel function in the gut epithelia. Cell, 2007. 131(5): p. 940-51]. We hypothesized that the …

Insights Into P53-Dependent Apoptotic Signaling And Cell Fate Vis-A-Vis Functional Cooperation Among Bcl-Xl, Cytoplasmic P53, And Puma, John C. Fisher

Theses and Dissertations (ETD)

Following DNA damage, nuclear p53 induces the expression of PUMA (p53 upregulated modulator of apoptosis), a BH3‑only protein that binds and inhibits the anti‑apoptotic BCL‑2 repertoire, including BCL‑xL. Structural investigations of PUMA and the BCL‑xL×PUMA BH3 domain complex by X‑ray crystallography and nuclear magnetic resonance (NMR) spectroscopy reveal a novel, PUMA‑induced, domain‑swapped dimerization of BCL‑xL that requires a π‑stacking interaction between PUMA W71 and BCL‑xL H113. PUMA is an intrinsically disordered protein, but upon interaction with BCL‑xL, PUMA W71 and the PUMA BH3 domain residues fold into an alpha helix and subtly remodel BCL‑xL to trigger its dimerization. Wild type …

Impact Of Adjuvants On The Antibody Responses To Pre-Pandemic H5n1 Influenza Vaccines, Ali Hassan Ellebedy

Theses and Dissertations (ETD)

Human influenza pandemics occur when influenza viruses to which the population has little or no immunity emerge and acquire the ability to transmit among humans. Since their emergence in 1996, human infections with highly pathogenic avian influenza A (H5N1) viruses presented a serious public health challenge. Additionally, H5N1 viruses caused significant agricultural and economic losses in the communities it has affected. Human infections with these viruses are rare but when they occur, these infections are highly fatal. A greater public health concern stems from the rapid evolution displayed by these viruses so far, which in turn might result in viruses …

Characterization Of The Sigma Factor Proteins And The Dna Binding Protein Euo Of Chlamydia, Cory L. Blackwell

Theses and Dissertations (ETD)

Chlamydia spp. are prokaryotic obligate intracellular pathogens with a unique, biphasic developmental cycle in which an infectious, extracellular form termed the elementary body (EB) interconverts with a metabolically active intracellular reticulate body (RB) within host cells. Subsets of genes are differentially expressed during the developmental cycle, and these genes are believed to be responsible for the transitions between the EB and RB forms. The goal of these studies was to explore two potential mechanisms that may function in regulating developmental cycle stage‑specific gene expression in chlamydiae: a cascade of sigma factor expression and the binding of the early stage protein …

Novel Insights Into Ubiquitin-Like Protein E1-E2 Interactions, Asad Taherbhoy

Theses and Dissertations (ETD)

Posttranslational modification of macromolecules by ubiquitin-like proteins (UBLs) such as ubiquitin, Sumo and NEDD8 regulate a vast array of processes in the cell. Transfer of UBLs to their target generally occurs by a series of molecular handoffs down an E1‑E2‑E3 cascade. We are interested in understanding how E1‑E2 pairs interact and mediate UBL transfer. To this effect, we studied two E1‑E2 pairs: the Sumo pathway (Sumo utilizes a canonical E1 and E2) and the Atg8 pathway (Atg8 is a UBL involved in autophagy that utilizes a non-canonical E1‑E2 pair).

Sumo conjugation is initiated by the heterodimeric Aos1‑Uba2 E1 enzyme (in …

Systemic Aav-Mediated Gene Therapy Using Epo-R76e To Protect Retinal Ganglion Cells From Optic Nerve Injury And Disease, Timothy A. Sullivan

Theses and Dissertations (ETD)

Neuroprotection is a strategy to prevent or reduce neuronal cell death regardless of the underlying cause. Erythropoietin (EPO) exhibits neuroprotective effects in a variety of in vitro and in vivo models of neuronal cell death although its classical function is the regulation of red blood cell production. EPO crosses the blood brain barrier and therefore can be delivered systemically. However, long term treatment with exogenous EPO causes over stimulation of the erythropoietic pathway which can be lethal. The erythropoietic and neuroprotective pathways are regulated by different receptors; further, it is possible to modify EPO to primarily, if not solely, activate …

The Biochemical Pathway Leading To Lpa Generation Upon Blood Coagulation, Alyssa Lynn Jefferson Bolen

Theses and Dissertations (ETD)

Platelet activation initiates an upsurge in 18:2 and 20:4 lysophosphatidic acid (LPA) production. The biochemical pathway responsible for LPA production during blood clotting is not fully understood. We have purified a phospholipase A₁ (PLA₁) from thrombin-activated human platelets using sequential chromatographic steps followed by fluorophosphonate‑biotin affinity labeling and proteomics. We identified acyl‑protein thioesterase 1 (aka. lysophospholipase A1, accession code O75608) as a novel PLA₁. Addition of this recombinant PLA₁ significantly increased the production of sn‑2‑esterified polyunsaturated LPCs and the corresponding LPAs in plasma. We next examined the regioisomeric preference of lysophospholipase …

Role Of Protein Kinase C Zeta (Pkcζ) In Regulation Of Epithelial Tight Junctions, Suneet Kumar Jain

Theses and Dissertations (ETD)

Occludin is hyperphosphorylated on Ser and Thr residues in intact epithelial tight junctions. The dynamics of epithelial tight junctions appear to involve reversible phosphorylation of occludin on Ser and Thr residues. In the present study we determined the role of PKCζ in occludin phosphorylation and the dynamics of tight junctions. Inhibition of PKCζ by specific PKCζ pseudo substrate rapidly reduced TER, increased inulin permeability and induced redistribution of occludin and ZO‑1 in Caco‑2 and MDCK cell monolayers without inducing cytotoxicity. Reduced expression of PKCζ also resulted in compromised tight junction integrity. Both PKCζ pseudo substrate and reduced expression of PKCζ …

A Behavioral And Anatomical Analysis Of Conditioned Taste Aversion In C57bl/6j And Dba/2j Mice, April Rebecca Glatt

Theses and Dissertations (ETD)

Conditioned taste aversion (CTA) has been commonly used as a model of learning and memory. Traditionally, CTA approaches have used a paradigm that follows the model of classical conditioning. This involves presentation of a novel tastant, such as sucrose (conditioned stimulus, CS), followed by an intraperitoneal injection of lithium chloride that induces gastric malaise (unconditioned stimulus, US), which results in the aversion of sucrose (conditioned response, CR). However, a more natural classical conditioning paradigm involves the consumption, rather than injection, of the US by using a self‑administration paradigm that allows for time‑dependent analysis of formation, generalization, and extinction of CTA …