ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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Description
Schizophrenia is considered a multifactorial disorder with complex genetic variants in response to environmental stimuli. However, the specific genetic contribution to schizophrenia risk is largely unknown. The transcription factor early growth response gene 3 (EGR3) can be activated rapidly after stimuli and thus may translate environmental stimuli into gene changes that influence schizophrenia risk. However, the downstream genes that may be regulated by EGR3 are not clear. While the 5-Hydroxytryptamine receptor 2A (5HT2AR) - encoding gene Htr2a has been implicated in the etiology of schizophrenia, the mechanisms by which Htr2a influences susceptibility to this illness are poorly understood. We previously found that in addition to schizophrenia-like abnormalities, Egr3 -/- mice have approximately 70% deduction of 5HT2AR level in the prefrontal cortex, which underlines their resistant to the sedating effect of clozapine. These findings indicate that the two schizophrenia candidate genes are in the same biological pathway that integrates multiple components resulting in schizophrenia. This dissertation is aimed to identify the mechanisms by which Egr3 regulates the expression of Htr2a in response to environmental stimuli like stress.
To determine if Egr3 alters Htr2a transcription under stress, I examined messenger ribonucleic acid (mRNA) levels of these two genes in wildtype (WT) and Egr3 -/- mice after 6hrs of sleep deprivation (SD). I found both genes are increased in WT mice after SD compared with controls. In addition, Egr3 is required for Htr2a induction because SD fails to induce Htr2a expression in Egr3 -/- mice. Next, I performed chromatin immunoprecipitation (ChIP) to determine if EGR3 binds to Htr2a promoter in vivo. I found a significant increase of EGR3 binding to Htr2a distal promoter 2hrs after seizure. To determine the functionality of this binding, I co-transfected the CMV- EGR3 vector or CMV- vector alone with the Htr2a distal promoter reporter clone. I found overexpression of EGR3 activates the Htr2a distal promoter-driven luciferase gene. Although the ChIP assay shows no direct binding of EGR3 to Htr2a proximal promoter, I found EGR3 overexpression activates Htr2a proximal promoter-driven luciferase gene. These findings suggest that EGR3 regulates Htr2a probably through both direct and indirect ways.
To determine if Egr3 alters Htr2a transcription under stress, I examined messenger ribonucleic acid (mRNA) levels of these two genes in wildtype (WT) and Egr3 -/- mice after 6hrs of sleep deprivation (SD). I found both genes are increased in WT mice after SD compared with controls. In addition, Egr3 is required for Htr2a induction because SD fails to induce Htr2a expression in Egr3 -/- mice. Next, I performed chromatin immunoprecipitation (ChIP) to determine if EGR3 binds to Htr2a promoter in vivo. I found a significant increase of EGR3 binding to Htr2a distal promoter 2hrs after seizure. To determine the functionality of this binding, I co-transfected the CMV- EGR3 vector or CMV- vector alone with the Htr2a distal promoter reporter clone. I found overexpression of EGR3 activates the Htr2a distal promoter-driven luciferase gene. Although the ChIP assay shows no direct binding of EGR3 to Htr2a proximal promoter, I found EGR3 overexpression activates Htr2a proximal promoter-driven luciferase gene. These findings suggest that EGR3 regulates Htr2a probably through both direct and indirect ways.
ContributorsZhao, Xiuli (Author) / Gallitano, Amelia (Thesis advisor) / Van Keuren-Jensen, Kendall (Committee member) / Lifshitz, Jonathan (Committee member) / Neisewander, Janet (Committee member) / Arizona State University (Publisher)
Created2017
Description
Traumatic brain injury (TBI) affects an estimated 1.7 million people in the United States each year and is a leading cause of death and disability for children and young adults in industrialized countries. Unfortunately, the molecular and cellular mechanisms of injury progression have yet to be fully elucidated. Consequently, this complexity impacts the development of accurate diagnosis and treatment options. Biomarkers, objective signatures of injury, can inform and facilitate development of sensitive and specific theranostic devices. Discovery techniques that take advantage of mining the temporal complexity of TBI are critical for the identification of high specificity biomarkers.
Domain antibody fragment (dAb) phage display, a powerful screening technique to uncover protein-protein interactions, has been applied to biomarker discovery in various cancers and more recently, neurological conditions such as Alzheimer’s Disease and stroke. The small size of dAbs (12-15 kDa) and ability to screen against brain vasculature make them ideal for interacting with the neural milieu in vivo. Despite these characteristics, implementation of dAb phage display to elucidate temporal mechanisms of TBI has yet to reach its full potential.
My dissertation employs a unique target identification pipeline that entails in vivo dAb phage display and next generation sequencing (NGS) analysis to screen for temporal biomarkers of TBI. Using a mouse model of controlled cortical impact (CCI) injury, targeting motifs were designed based on the heavy complementarity determining region (HCDR3) structure of dAbs with preferential binding to acute (1 day) and subacute (7 days) post-injury timepoints. Bioreactivity for these two constructs was validated via immunohistochemistry. Further, immunoprecipitation-mass spectrometry analysis identified temporally distinct candidate biological targets in brain tissue lysate.
The pipeline of phage display followed by NGS analysis demonstrated a unique approach to discover motifs that are sensitive to the heterogeneous and diverse pathology caused by neural injury. This strategy successfully achieves 1) target motif identification for TBI at distinct timepoints and 2) characterization of their spatiotemporal specificity.
Domain antibody fragment (dAb) phage display, a powerful screening technique to uncover protein-protein interactions, has been applied to biomarker discovery in various cancers and more recently, neurological conditions such as Alzheimer’s Disease and stroke. The small size of dAbs (12-15 kDa) and ability to screen against brain vasculature make them ideal for interacting with the neural milieu in vivo. Despite these characteristics, implementation of dAb phage display to elucidate temporal mechanisms of TBI has yet to reach its full potential.
My dissertation employs a unique target identification pipeline that entails in vivo dAb phage display and next generation sequencing (NGS) analysis to screen for temporal biomarkers of TBI. Using a mouse model of controlled cortical impact (CCI) injury, targeting motifs were designed based on the heavy complementarity determining region (HCDR3) structure of dAbs with preferential binding to acute (1 day) and subacute (7 days) post-injury timepoints. Bioreactivity for these two constructs was validated via immunohistochemistry. Further, immunoprecipitation-mass spectrometry analysis identified temporally distinct candidate biological targets in brain tissue lysate.
The pipeline of phage display followed by NGS analysis demonstrated a unique approach to discover motifs that are sensitive to the heterogeneous and diverse pathology caused by neural injury. This strategy successfully achieves 1) target motif identification for TBI at distinct timepoints and 2) characterization of their spatiotemporal specificity.
ContributorsMartinez, Briana Isabella (Author) / Stabenfeldt, Sarah E (Thesis advisor) / Lifshitz, Jonathan (Committee member) / Sierks, Michael (Committee member) / Kleim, Jeffrey (Committee member) / Arizona State University (Publisher)
Created2020