Molecular Biology Commons^™

Riluzole As A Dual-Targeted Radiosensitizer For Osteosarcoma: Targeting Tumor Cells And Angiogenic Vasculature To Enhance Single High-Dose Radiotherapy Efficacy, Pooja P. Rao

Dissertations, Theses, and Capstone Projects

Osteosarcoma (OS), the most common primary bone malignancy of children and young adults, is intrinsically radioresistant, and outcomes for patients with unresectable or metastatic disease have not improved in over four decades. Single-dose radiation therapy (SDRT) is a potent modality against radioresistant, highly vascularized sarcomas, but its application in OS is constrained by dose-dependent normal tissue toxicity. Radiosensitizers achieving tumor control at lower doses therefore offer a direct route to widening the therapeutic window. Critically, OS radioresistance is not tumor-cell-autonomous. It emerges from two coordinated compartments: aberrant DNA repair and antioxidant capacity intrinsic to the tumor cell, and a radioprotective, …

The Defining Role Of Ago4 And Its Catalytic Activity During De Novo Rna-Directed Dna Methylation, Tianyi Li

Arts & Sciences Graduate Student Theses and Dissertations

Plant transposable elements and transgenes are continuously targeted for transcriptional repression via the pathway of RNA-directed DNA methylation (RdDM). Although perpetual RdDM of the endogenous genomic loci has been well studied in the field, much less is known about the de novo RdDM pathway, the pioneering round of DNA methylation responsible for triggering and initiating silencing of new transgenes. Despite being two distinct pathways, both perpetual and de novo mechanisms of RdDM require the production of small interfering RNAs (siRNAs) and the key proteins of the ARGONAUTE4 (AGO4) clade. However, the order and likely mechanism of recruitment of AGO4 to …

Polyphenol Diet And Exercise As Neuroprotection From Effects Of Alzheimer's Disease, Michelle Morgan

Loma Linda University Electronic Theses, Dissertations & Projects

Healthy non-pharmacological lifestyle factors, such as regular physical exercise and a dietary supplementation, have been shown to significantly improve cognitive outcomes over time compared to a more sedentary lifestyle and poor diet. Furthermore, exercise may serve as a potential protective factor in attenuating the effects associated with cognitive decline that are characteristic of neurodegenerative disorders, such as Alzheimer's disease (AD). Further, evidence indicates that certain diet interventions can also attenuate the effects of neurodegeneration and positively impact longevity. Supplementation of polyphenols, such as ellagic acid (EA), which are abundant in pomegranate juice, may help provide neuroprotective benefits and elicit a …

A Genetic Analysis Of The Rare Endemic Astragalus Ripleyi Barneby, Juan Antonio Jaramillo-Chico

Master's Theses

Astragalus ripleyi Barneby is a rare endemic species found in the San Luis Valley of the southern portions of the Rocky Mountains in Colorado and New Mexico. Though not federally listed as endangered, the species is on the Bureau of Land Management’s Sensitive Species List, warranting protection and continued management. This study aims to provide information about the genetic health of the species to inform conservation efforts and provide updated management recommendations. A genetic health analysis was conducted investigating the levels of diversity present in the species, how genetic diversity is structured across the known range of the species and …

The Rpm-1/Phr Signaling Hub Modulates Tau-Induced Neurodegeneration Through Regulation Of Microtubule Stability And Mapk Pathways In C. Elegans, Xinxing Ding

Theses and Dissertations

Neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia, are characterized by the accumulation of pathological tau proteins and progressive neuronal loss. Although research regarding tau-mediated toxicity is extensive, the specific pathology that determine whether neurons maintain homeostasis or succumb to collapse under tau-induced stress remain incompletely elucidated. A central, yet still insufficiently understood, feature of these diseases is the disruption of the microtubule (MT) cytoskeleton . The PHR protein family is evolutionarily highly conserved; within this family, RPM-1 in C. elegans functions as an intracellular signaling hub that regulates axon development, synapse formation, axon termination, and various microtubule-associated processes. This …

Uv Damage Mapping Reveals Different Impacts Of Xpd Mutations On Global Genomic And Transcription-Coupled Dna Repair, Allyson Hoag

Biomedical Sciences ETDs

Nucleotide Excision Repair (NER) is a fundamental cellular process that removes bulky and helical distorting lesions from the genome through the separate responses of its two subpathways – global genomic (GG-NER) and transcription coupled (TC-NER) DNA repair. The pathways converge with the recruitment of the TFIIH complex, a key step that is mediated by the translocase and helicase activities of  its XPD subunit. Germline mutations in XPD result in the clinical disorders, Xeroderma Pigmentosum (XP) and XP combined with Cockayne Syndrome (XP/CS). The goal of this thesis was to understand if XPD XP and XP/CS mutations differentially impact GG-NER and …

A Rho5-Cnc1-Dnm1 Signalling Module Coordinates Multi-Organelle Execution Of Regulated Cell Death In Yeast, Justin Bauer

Theses and Dissertations

Regulated cell death is a conserved process with major implications for health and disease, yet how yeast cells integrate stress signals to determine survival versus death remains unclear. This thesis investigates Cyclin C (Cnc1), a conserved Mediator kinase module component with both transcriptional and mitochondrial roles. Together with Cdk8 Cnc1 primarily represses stress response genes, while upon stress it translocates to the mitochondria to induce mitochondrial fragmentation with the dynamin-related GTPase Dnm1. Using structure-guided separation-of-function mutants, I demonstrate that Cnc1-dependent death requires its mitochondrial function rather than its transcriptional role, and that its effector Dnm1 acts as a signaling node …

Elucidating The Function Of Yedk In Response To Dna Damage, Hank Munro

University Honors Theses

Apurinic/Apyrimidinic (AP) sites are one of the most prevalent forms of DNA damage. These lesions arise spontaneously or during base excision repair of modified DNA bases and are potentially mutagenic in both mammalian and bacterial cells. 5-hydroxymethylcytosine binding, ES cell specific (HMCES), a protein found in eukaryotic cells, has been shown to form a stable DNA-protein crosslink with AP sites in single stranded DNA and to reduce the number of AP sites occurring either spontaneously or after alkylative DNA damage, resulting in increased genome stability. YedK, the Escherichia coli ortholog of HMCES exhibits some of the same biochemical properties as …

The Neuroprotective Effect Of Cdc42 Inhibition In The G93a Mutant Hsod1 Mouse Model Of Als, Andrea Koly

Undergraduate Theses, Capstones, and Recitals

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease characterized by the selective loss of upper and lower motor neurons, leading to muscle weakness, neuromuscular junction (NMJ) degeneration, paralysis, and eventual death due to respiratory failure. Despite extensive research, effective disease-modifying therapies remain limited, underscoring the need to identify novel molecular targets involved in ALS pathogenesis. Dysregulation of Rho family GTPases has been implicated in neurodegeneration, with Rac and Rho exerting opposing effects on neuronal survival; however, the role of the closely related GTPase Cdc42 remains poorly understood in ALS. In this study, the therapeutic potential of inhibiting …

Targeting Inflammatory And Growth Signaling Pathways In Breast Cancer Through Diet, Microbiome, And Metabolite Interactions, Brittany Lorraine Witt

ETDs from 2020-2029

Breast cancer (BC) accounts for 1 in 3 (or 30%) of all new female cancers each year and is the most common malignant cancer in women in the United States. Since the 1990s, there has been a 44% decrease in BC, but there is still a significant gap between certain groups in terms of mortality rates. Black women have a higher mortality rate and risk for triple-negative breast cancer (TNBC). This may be due to social (inadequate access to health care facilities, insurance, or completion of therapy) and biological (genetic mutations, tumor characteristics, or comorbidity) factors between races and other …

Dock7 Is A Novel Modifier Of Duchenne Muscular Dystrophy Pathology, Katherine English

ETDs from 2020-2029

Duchenne muscular dystrophy (DMD) is a progressive, x-linked neuromuscular disorder affecting 1/5000 male births every year. DMD results from mutations in DMD, a critical structural protein within the muscle. In the absence of Dystrophin, the muscle degrades, increasing inflammation, destabilizing the cell membrane and going through constant cycles of regeneration which depletes the stem cell population. Over time, muscle tissue is replaced by fibrosis and adipose tissue, leading to loss of ambulation, respiratory and cardiac failure leading to death by early 20s. The standard of care for DMD patients is corticosteroid treatment. However, gene therapies have recently emerged which present …

Elucidating The Role Of The Rnf20 Histone Modifier In Pancreatic Beta Cells, Tanya Hans Pierre

ETDs from 2020-2029

Diabetes is defined as a loss of functional beta cell mass. It is classically categorized into Type 1 Diabetes (T1D), immune-mediated beta cell destruction and Type 2 Diabetes, which is characterized by whole body insulin resistance alongside beta cell dysregulation. The incidence of diabetes worldwide has risen annually. Despite the presence of therapeutic interventions, diabetes’ heterogeneity can prompt ineffective glycemic control and the development of diabetes-associated comorbidities. For that reason, new approaches to glycemic control for individuals with diabetes are required. One approach to restore glucose homeostasis is beta cell replacement therapy, in which stem cells are programmed into beta-like …

In Vitro Reversal Of Abc Transporter Mediated Multidrug Resistance In Human Ovarian And Non-Small Cell Lung Cancer Models, Alison K. Kellom, Pia D. Vogel

Biological Sciences Theses and Dissertations

One of the major causes of treatment failure in aggressive cancers is multidrug resistance (MDR), which is linked to the overexpression of membrane efflux proteins that export chemotherapeutics from cancer cells. This mechanism prevents chemotherapeutic drugs from reaching cytotoxic concentrations intracellularly, allowing the cancer to survive. Two primary mediators of this mechanism are P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP). P-gp and BCRP are transmembrane ATP-binding cassette (ABC) transporters that are frequently overexpressed in MDR cancers. They utilize the binding and hydrolysis of ATP to transport a diverse range of amphipathic molecules of varying size (Schinkel and Jonker, 2003), …

Bax Activation Through The N-Terminal Bh3-Like Domains Of Vdac1 And Vdac2, Autumn A. Peters

Honors Theses

Voltage-dependent anion channels (VDACs) are central to mitochondrial function by mediating metabolite diffusion across the mitochondrial outer membrane (MOM). Two isoforms­­­­­­­­­­­,­­­­­­­­­­­­­­­­­­­­­­­­­­­­ VDACs 1 and 2, are also implicated in apoptosis based on interactions with Bcl-2 family proteins that control this process, including Bax and Bcl-xL. Activation of the pro-apoptotic protein Bax by interaction with ‘BH3-only’ proteins, such as Bim or Bid, induces MOM permeabilization to signal apoptosis, yet accumulating evidence indicates VDACs 1 and 2 may also affect Bax. We discovered that the VDAC N-terminal domains contain high sequence similarity to the conserved BH3 domains within Bcl-2 family members that …

Analysis Of Developmental Cardiogenic Processes Mediated By Fox And Zinc-Finger Transcription Factors, Rajnandani Katariya

All-Inclusive List of Electronic Theses and Dissertations

Cardiogenesis is a highly choreographed biological process requiring the precise integration of gene regulatory networks to govern cell division, fate determination, and spatial positioning. Disruptions in these mechanisms lead to congenital heart defects (CHDs), which affect approximately 1% of live births globally. Due to the evolutionary conservation of cardiac signaling pathways and the structural homologies between the Drosophila dorsal vessel and the early vertebrate heart tube, Drosophila melanogaster serves as a powerful model for dissecting the fundamental mechanisms of heart development. This dissertation investigates the molecular orchestration of cardiac development, specifically focusing on the roles of the transcription factors Jumu …

Reconstruction Of Fox Transcription Factor-Regulated Subnetworks Mediating Cardiac Progenitor Cell Divisions, Md Rezaul Hasan

All-Inclusive List of Electronic Theses and Dissertations

Congenital heart disease (CHD) is the most common congenital anomaly worldwide, affecting approximately 1% of live births, corresponding to 1.35 million infants born with CHD each year, and remains a leading cause of infant mortality; therefore, it is urgent to understand the genetic and molecular mechanisms underlying CHD for advancing early diagnosis and treatment. Because many aspects of the Drosophila heart formation are highly reminiscent of vertebrate heart development, Drosophila melanogaster serves as a simple yet powerful model system for studying cardiac development and CHD. While at least eight Forkhead box (Fox) transcription factors (TFs) are required for proper cardiac …

Analysis Of The Effects Of Astaxanthin On Human Colorectal Cancer Cells, Kara A. Walters

Theses/Capstones/Creative Projects

Astaxanthin (AXT) is an antioxidant carotenoid that is produced by the microalgae Haemococcus pluvialis. This supplement is best known for its potential health benefits including anti-inflammatory, antitumor, immunomodulatory, anticancer and antidiabetic activities. Astaxanthin is marketed as an oral dietary supplement and is widely used in the nutraceutical industry as well as a coloring agent in the food industry. Since Astaxanthin has been increasingly popular as a dietary supplement, cytotoxicity is relevant to consumer exposure. Obtaining the IC50, the concentration that inhibits 50% of cell growth, is important to find how Astaxanthin may interact with cancer, and this can be found …

Developing A Protocol For Non-Cellular Transplantation Of Donor Mitochondria Into Recipient Cells, Andrew Parton

Honors Theses

Tumor innervation has emerged as a critical feature of cancer progression, with increased nerve density correlating with enhanced aggressiveness, metastatic dissemination, and poor clinical outcome. However, the functional contribution of neurons to tumor biology remains incompletely defined. We recently identified the intercellular transfer of mitochondria from neurons to cancer cells as a mechanism that promotes tumor progression. We therefore hypothesized that disruption of this transfer could attenuate tumor aggressivity. To directly investigate this process, we developed an approach to isolate mitochondria from donor cells and transplant them into recipient cancer cells independently of canonical cell-cell interactions. Transferred mitochondria were tracked …

Genome-Wide Phenotypic Characterization Of Mycobacteriophage Mercurio, Tyler Downs

Departmental Honors & Graduate Capstone Projects

Bacteriophages, or phages, are being piloted as a supplemental or alternative therapeutic to antibiotics against drug-resistant Mycobacterium pathogens, such as M. tuberculosis, which pose a global public health crisis.  Characterizing bacteriophage genomes can provide insights into efficacy in phage therapy before implementation or elucidate new targets to manipulate bacterial growth.  Overexpression of individual phage genes is useful to study a gene product’s function independent of others.  Here, the results of phage Mercurio plasmid library overexpression in plate-based assays are described.  Mercurio infects nonpathogenic Mycobacterium smegmatis and is genetically related to bacteriophages infecting pathogenic Mycobacterium species.  Eleven gene products of …

Phenotypic Contribution And Regulation Of Vibrio Parahaemolyticus Cold-Shock Protein Homologue Vp1889, Oleg Borisovich Ermolinsky

Theses and Dissertations

Vibrio parahaemolyticus is the primary causative agent of a form of gastroenteritis called vibriosis commonly acquired from ingestion of raw and undercooked seafood. The primary mitigation of seafood-borne illnesses is immediate storage on ice following catch, which inhibits bacterial metabolism and replication. Mesophilic bacteria such as V. parahaemolyticus induce expression of cold-shock proteins in a process named the cold shock response, which facilitates survival at low temperatures. V. parahaemolyticus bears 3 homologues of the major Escherichia coli cold-shock protein CspA, an RNA chaperone. Induction of E. coli CspA at low temperatures depends on autogenous modulation by its mRNA structure, which …

Membrane Organization Of Rheb And Rhoa: Roles In Function And Allosteric Druggability, Chase M. Hutchins

Dissertations and Theses (Open Access)

Small GTPases of the Ras superfamily are membrane-bound molecular switches that regulate nearly all major cellular processes, and their dysregulation drives cancers, neurological disorders, and metabolic diseases. While anchored to cellular membranes, the catalytic domains of small GTPases undergo orientation dynamics, adopting distinct configurations that can occlude or expose effector-binding surfaces and modulate signaling output. These dynamics have been characterized in the Ras oncoproteins, but whether they extend across the superfamily and influence allosteric druggability has remained unknown.

In this dissertation, I address these questions through Rheb and RhoA, two small GTPases with complementary differences in subfamily lineage, membrane localization, …

Abnormal Trafficking And Processing Of Multiple Matrix Metalloproteinases Drive Cartilage Defects In Congenital Disorders Of Glycosylation, Chia-Lun Wu

All Dissertations

Congenital Disorders of Glycosylation (CDG) are rare metabolic diseases caused by defects in glycosylation. Despite identification of over 200 CDG types, the mechanisms linking glycosylation defects to diverse clinical phenotypes remain unclear. This dissertation uses zebrafish models of PMM2-CDG and STT3-CDG to redefine CDG pathogenesis, shifting from a simple glycan deficiency model to one involving disrupted cellular spatial organization.

We identify a protease-dependent pathway underlying craniofacial cartilage defects. Specifically, defective proteolytic processing of N-cadherin, a key adhesion molecule in chondrogenesis, is a central driver of pathology. We further uncover an unconventional trafficking mechanism in which ER stress and altered secretory …

Understanding The Role Of Toxs As A Bile Sensing Component Of The Toxrs Virulence Regulatory System In Vibrio Spp., Minje Kim

Dartmouth College Ph.D Dissertations

Pathogenic Vibrio bacteria, such as V. cholerae and V. parahaemolyticus, colonize in the human small intestine to cause severe gastrointestinal disease. During the infection, these bacteria encounter bile salts, antimicrobial cholesterol metabolites secreted into the intestine. Pathogenic Vibrio species have evolved to utilize bile salts as signals to regulate virulence. The signaling depends in part on ToxRS, a conserved co-component transmembrane transcription regulator. ToxRS consists of the transcription factor ToxR and its membrane-tethered binding partner ToxS. ToxS is required for ToxR stability and full transcriptional activity. Although bile salts are known to influence ToxRS-dependent virulence gene expression, the molecular …

Characterization Of Snrk1 Signaling In Rice Growth, Reproduction, And Stress Responses Using Phenotypic And Omics Analysis, Maria Clara Faria-Bates

Graduate Theses and Dissertations

SnRK1 is an evolutionarily conserved protein kinase belonging to the SNF1/AMPK family that is composed of a catalytic subunit (α) and two regulatory subunits (β and βγ), and it has a major role in adjusting growth in response to the energy status. SnRK1 phosphorylates and alters the activities of enzymes involved in metabolism and regulates gene expression by altering the activity of chromatin-remodeling enzymes or transcription factors. Rice contains three functional paralogs of SnRK1α: OsSnRK1αA (Os05g0530500), OsSnRK1αB (Os8g0484600), and OsSnRK1αC (Os03g0289100). Although SnRK1 is known to play a central role in plant growth and stress responses, the functional specialization of …

Pepper Spray Exposure And The Effect On Dna Profiling Of Blood, Brandon Schmakel

Honors Projects

Pepper spray is a common self defense tool used in both law enforcement and civilian settings, with the goal of incapacitating the sprayed individual. In real casework where pepper spray was used, a red-brown stain which tested positive presumptively for blood provided no DNA profile after further testing six months later. A previous graduate student, Emma Crawn, attempted to emulate these casework conditions and instead achieved a DNA profile with slight indications of inhibition or degradation. Further analysis of active pepper spray ingredients such as Oleoresin Capsicum (OC) and Chloroacetophenone (CN) reveals that there are observed reactions, such as oxidation, …

The Pam-1 Aminopeptidase Does Not Protect Against Ptl-1 Mediated Neurodegeneration In C. Elegans., Ethan E. Schuff

Honors College Theses

Debilitating neurodegenerative conditions are increasingly prevalent in our aging population, yet treatment options remain limited. Though neurodegenerative diseases vary in pathophysiology and clinical manifestations, these diseases are related to one another in that many involve misfolded proteins. Tau is a member of the microtubule-stabilizing MAPT/MAP2/MAP4 family, and misfolded tau proteins form the neurotoxic aggregates called neurofibrillary tangles (NFTs) found in the brains of patients with Alzheimer's disease and other neurodegenerative diseases. Designing a study to elucidate the neurotoxic role of tau is difficult because other MAPs may have compensatory mechanisms which confound study data. Caenorhabditis elegans (C. elegans) …

Establishment Of A Hek293t Cell Model System To Investigate Direct Intracellular Interactions Between Amyloid-Β (Aβ) And The Nlrp3 Inflammasome, Cristina Sinobas Pereira

Dissertations

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia worldwide. While Amyloid-β (Aβ) aggregation is a defining pathological feature, increasing evidence highlights chronic neuroinflammation as a critical contributor to disease progression. Soluble Aβ assemblies can act as damage associated molecular patterns (DAMPs) including activation of the NLRP3 inflammasome, which links amyloid pathology to sustained inflammatory responses in the brain (Heneka et al., 2015; Nakanishi et al., 2018). However, the molecular mechanisms by which specific Aβ conformations influence inflammasome assembly remain incompletely understood.This study aimed to investigate whether distinct aggregation states of amyloid β42 (Aβ42) are …

Exploration Of A Relationship Between The Activities Of Trail And 4’-Trifluoromethoxychalcone., Abigail C. Ernst

Undergraduate Theses

Cancer is the overgrowth of dysregulated or mutated cells that affects 1 in 3 Americans. Chalcones are natural products with many possible derivatives, such as 4’-trifluromethoxychalcone (4TF), developed in Dr. Krzysiak’s lab, which exhibit anticancer activity against cancer cell lines. Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) is a tumor surveillance cytokine that acts on two receptor types: death receptors and decoy receptors. One way cancer cells can become resistant to TRAIL is by upregulating decoy receptors and/or downregulating death receptors. In this study, MTS assays evaluated the potential relationship between TRAIL and 4TF that sensitizes A549 cells to TRAIL. The …

Biophysical Insights Into A Cryptic, Hydrophobic Binding Site On Pcna, Alexis Dispensa

Theses and Dissertations

Proteins are dynamic molecules whose functional landscapes extend beyond static structural representations. Transient cryptic pockets (buried cavities that emerge through protein motion) represent underexplored targets for allosteric regulation and drug discovery. General anesthetics are small, lipophilic, weakly polar molecules that are well suited to partition into such hydrophobic sites. In this work, environment-sensitive fluorescence, photoaffinity labeling, mass spectrometry, mutational analysis, and microsecond molecular dynamics simulations were integrated to discover and characterize a cryptic, highly apolar binding site within the hydrophobic core of human proliferating cell nuclear antigen (PCNA), a central scaffold in DNA replication and repair. Using the solvatochromic fluorescent …

Discovering Drug-Like Compounds By Targeting Protein-Protein Interactions Using A Yeast-3-Hybrid System, Chesley C. Blake

Senior Theses

Protein-protein interactions are important targets in cancer biology as they can make historically “undruggable” proteins viable drug targets. However, the current approach to targeting protein-protein interactions relies on the use of small molecule drugs, which have low efficiencies as they must cover a large surface area of the interaction. Further, traditional drug therapies often lead to off-target toxicity, limiting therapeutic specificity. The objective of this project is to develop a selection system in yeast to identify short peptide sequences that can disrupt protein-protein interactions specific to cancer cells. Following proof of principle and development of the AH109 yeast strain having …