Bioinformatics Commons^™

Dna Methylation-Based Epigenetic Biomarkers In Cell-Type Deconvolution And Tumor Tissue Of Origin Identification, Ze Zhang

Dartmouth College Ph.D Dissertations

DNA methylation is an epigenetic modification that regulates gene expression and is essential to establishing and preserving cellular identity. Genome-wide DNA methylation arrays provide a standardized and cost-effective approach to measuring DNA methylation. When combined with a cell-type reference library, DNA methylation measures allow the assessment of underlying cell-type proportions in heterogeneous mixtures. This approach, known as DNA methylation deconvolution or methylation cytometry, offers a standardized and cost-effective method for evaluating cell-type proportions. While this approach has succeeded in discerning cell types in various human tissues like blood, brain, tumors, skin, breast, and buccal swabs, the existing methods have major …

Methylation Patterns Across Tissue Type And Time In Peromyscus Leucopus: A Targeted Museum Study, Loryn Smith

Master's Theses

Museum specimens are a vital data source for many types of studies. One relatively new use includes studying methylation patterns. Methylation patterns are a form of epigenetics or how gene expression changes without alteration of the genetic code. These patterns have been examined in many mammals. However, the focus has previously been on overall epigenetic patterns. Few studies have investigated whether methylation patterns differ across tissue types, time, or preservation method. In this study, I compared methylation patterns in muscle, liver, toe pads, and nasal bones from Peromyscus leucopus (white-footed mouse) museum specimens collected in 2022, 2018, 2014, and 2008 …

Multi-Omic And Single-Cell Characterization Of A 3d Skin-Like Tissue Model Of Systemic Sclerosis With A Focus On Epigenetics, Tamar R. Abel

Dartmouth College Ph.D Dissertations

Systemic sclerosis (SSc) is a rare fibrotic autoimmune disease with high mortality and limited FDA approved therapies. Clinical concordance among twins is low; however, a modest familial heritability implicates complex interactions between polygenic risk alleles and the environment as causal – interactions that are mediated by epigenetics. Although mechanisms of tissue fibrosis have been successfully identified and targeted in established in vitro models for SSc, these molecules have ultimately failed in clinical trials. This likely reflects the lack of a reliable in vitro model that faithfully recapitulates the disease.

I utilized a 3D skin-like tissue model to study SSc skin …

Dna Methylation And The Response To Infection In Introduced House Sparrows, Melanie Gibson

Electronic Theses and Dissertations

Epigenetics is the study of molecular modification of a genome without changing its base pairs. The most studied type of epigenetic mechanism is DNA methylation, which is capable of turning a gene “on” or “off.” Epigenetic potential is the capacity to which an individual can have methylation on its genome. The more CpGs available, the greater the epigenetic potential. In invasive species, genetic variation has been observed to be paradoxical: not much of it exists on a genomic level, but epigenetically, phenotypic variation can occur. The focus on shift in gene expression in this study is on Toll-Like Receptor 4 …

An Investigation Of Epigenetic Mechanisms Driving The Biology Of Head And Neck Squamous Cell Carcinoma, Scot Carson Callahan

Dissertations & Theses (Open Access)

Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer worldwide and is associated with significant morbidity and mortality. To date, the majority of work in the field has focused on genomic alterations such as mutations and copy number alterations. However, the clinical success of targeted therapies that exploit known genomic alterations, such as EGFR mutations, has remained mixed. Over the past decade, the importance of epigenetic regulators has come to the forefront, with the realization that many of these genes are mutated in cancer. Despite this realization, the role of epigenetics in regulating tumorigenesis, progression and …

Identification Of Dna Methylation Episignatures For Classification And Phenotype/Genotype Correlation In Mendelian Neurodevelopmental Disorders, John Reilly

Electronic Thesis and Dissertation Repository

ABSTRACT: Diagnosis for neurodevelopmental disorders poses numerous challenges, related to the lack of specific findings and limited understanding of clinical impact of the majority of genetic variation. Epigenomics mechanisms involve chemical modifications in DNA that involve a range of cellular mechanisms. DNA methylation is an epigenetic mechanism involving addition and removal of methyl groups to cytosine residues. These methylation signals form episignatures; patterns of methylation that can be used as biomarkers capable of differentiating neurodevelopmental disorders. EpiSigns have enabled molecular diagnosis of a number of genetic conditions, classification of variants of unknown significance, and provided insights into the pathophysiology of …

Determining Haplotype Specific X Chromosome Inactivation State And Related Epigenetic Features In Female X-Linked Genes, Ariah Dawn Mackie

Cal Poly Humboldt theses and projects

Females with heterozygous X-linked mutations are prone to pseudo-haploinsufficiency because random X chromosome inactivation (XCI) silences one of their two X chromosomes. A prior study explored the theory that reactivating the silenced healthy allele could be a treatment for pseudo-haploinsufficient females. The next step was to evaluate this approach in a clinically relevant stem cell model of the rare neurological disease CDKL5 Deficiency Disorder (CDD). It was necessary to validate X-inactivation state with respect to CDKL5 allele expression in one of these models. We explored CDKL5 allele expression in two populations of CDD female patient-derived induced pluripotent stem cells (iPSCs) …

Unveiling Global Roles Of G-Quadruplexes And G4-22 In Human Genetics, Ruth Barros De Paula

Dissertations & Theses (Open Access)

G-quadruplexes are non-B DNA structures formed by four or more runs of repeated guanines that confer unique features to living organism’s genomes. These sequences are enriched in regulatory regions, such as promoters and 5’ UTRs, and have distinct regulatory roles in both health and disease states. Even though previous studies showed the impact of G4 in gene expression, none of them summarized the location-specific effect of G4. Also, there is no broad understanding about the most common G4 repeat in the human genome, named here as G4-22, and how it links to the evolution of mammals and their biology. In …

Discovery Of Novel Ubiquitin- And Methylation-Dependent Interactions Using Protein Domain Microarrays, Jianji Chen

Dissertations & Theses (Open Access)

Post-translational modifications (PTMs) drive signal transduction by interacting with "reader" proteins. Protein domain microarray is a high throughput platform to identify novel readers for PTMs. In this dissertation, I applied two protein domain microarrays identifying novel readers for histone H2Aub1 and H2Bub1, and H3TM K4me3. Ubiquitinations of histone H2A at K119 (H2Aub1) and histone H2B at K120 (H2Bub1) function in distinct transcription regulation and DNA damage repair pathways, likely mediated by specific "reader" proteins. There are only two H2Aub1-specific readers identified and no known H2Bub1-specific readers. Using a ubiquitin-binding domain microarray, I discovered the phospholipase A2-activating protein (PLAA) PFU domain …

Computational Analysis Of Non-Cpg Dna Methylation In The Mammalian Nervous System, Dennis Yawen Wu

Arts & Sciences Electronic Theses and Dissertations

Noncanonical forms of DNA methylation, especially non-CpG DNA methylation, play essential roles in the neuronal epigenome, and have only recently begun to be characterized. While most DNA methylation within mammals is found in a CG context and maintained by DNMT1, neurons contain uniquely high levels of non-CpG methylation, such that the total amounts of methylation in non-CpG contexts equals or surpasses the total amounts of methylation in CG contexts. Non-CpG methylation, unlike CpG methylation, cannot be maintained by DNMT1, and must be established by the de novo methyltransferase DNMT3A.One unique characteristic of non-CpG methylation compared to canonical CpG methylation is …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

Chromatin Digestion By The Chemotherapeutic Agent Bleomycin Produces Nucleosome And Transcription Factor Footprinting Patterns Similar To Micrococcal Nuclease, Joshua Michael Stolz

Theses and Dissertations

Bleomycin (BLM), a glycopeptide antibiotic commonly used in chemotherapeutic treatments, has been shown to produce single and double stranded DNA breaks. Subsequent analysis of DNA fragmentation patterns has demonstrated preferential digestion of chromatin in the TSS of active genes and the ability to produce nucleosome-sized fragments within intact chromatin. Nucleosome positioning plays a critical role in the regulation of gene activation. Currently, micrococcal nuclease (MNase) is used as the standard for mapping the position of nucleosomes in the genome. In order to identify whether BLM can be used as an effective nucleosome-mapping agent, BLM was used to digest chromatin in …

Molecular Consequences Of High Taz Expression In Gliomas, Visweswaran Ravikumar

Dissertations & Theses (Open Access)

Diffuse high grade gliomas are complex and lethal neoplasms of the adult central nervous system that are driven by a range of genetic and epigenetic alterations. Molecular classification of these tumors has identified different transcriptional subtypes, the most notable being Proneural (PN) and Mesenchymal (MES) classes. The most aggressive forms of the disease have a Mesenchymal expression signature, with reported PN-to-MES transition occurring with tumor progression. Master regulatory analysis has identified the transcriptional co-activator TAZ (WWTR1) as a major driver of the MES transition. Overexpression of this single protein in glioma stem cells has been shown to drive a transition …

Understanding The Molecular And Cellular Functions Of Odd-Skipped Related 1 In Outflow Tract Development, Menglan Xiang

Theses and Dissertations

The cardiac outflow tract (OFT) is a transient conduit that connects the embryonic heart chambers to the vascular network. Transcription factor Osr1 promotes the proliferation and cell cycle progression of second heart field (SHF), an essential cell population that contribute to the developing OFT. In this study, we investigated the role of Osr1 in OFT development on cellular and molecular levels using a systems biology approach. We observed OFT rotation and elongation defects, as well as double-outlet right ventricle and overriding aorta as a result of SHF-specific deletion of Osr1. Using genetic inducible fate mapping, we showed that Osr1-expressing SHF …

Mu Transposon Insertion Sites And Meiotic Recombination Events Co-Localize With Epigenetic Marks For Open Chromatin Across The Maize Genome, Sanzhen Liu, Cheng-Ting Yeh, Tieming Ji, Kai Ying, Haiyan Wu, Ho Man Tang, Yan Fu, Daniel S. Nettleton, Patrick S. Schnable

Dan Nettleton

The Mu transposon system of maize is highly active, with each of the ∼50–100 copies transposing on average once each generation. The approximately one dozen distinct Mutransposons contain highly similar ∼215 bp terminal inverted repeats (TIRs) and generate 9-bp target site duplications (TSDs) upon insertion. Using a novel genome walking strategy that uses these conserved TIRs as primer binding sites, Mu insertion sites were amplified from Mu stocks and sequenced via 454 technology. 94% of ∼965,000 reads carried Mu TIRs, demonstrating the specificity of this strategy. Among these TIRs, 21 novel Mu TIRs were discovered, revealing additional complexity of …

The Role Of H3k4 Methyltransferases In Drosophila Memory, Nicholas Raun

Electronic Thesis and Dissertation Repository

Gene transcription required for long-term memory requires the modification of histones. However, there are still many uncertainties about the identity and spatial expression of genes regulated by histone modifications during memory related processes. In this project I examined the role of Drosophila melanogaster methyltransferases Set1 and trx in courtship memory. Genetic knockdown of Set1 and trx in the mushroom body (MB) revealed that Set1 was necessary for short- and long-term memory, while trx was only required for long-term memory. Transcriptional profiling of MBs following trx-knockdown revealed expression changes in MB-enriched genes and genes involved in RNA processing. Among the …

Dna Methylation And Genetic Divergence Associated With An Inducible Defensive Response In Mimulus Guttatus, David Farr

All Master's Theses

Phenotypic plasticity allows many organisms to respond to their environment by changing their phenotype, but the mechanisms to do so are not well understood. Yellow Monkeyflower (formerly Mimulus guttatus; now Erythranthe guttata) is one such organism that can serve as a model to promote our understanding of these mechanisms due to its striking response to insect herbivory. Monkeyflower responds to leaf damage by increasing the number of hair-like glandular trichomes, a putative defensive trait that reduces the magnitude of damage by insects. This plastic response is transgenerationally inherited in a way that is sensitive to genome-wide demethylation when …

Genetic And Epigenetic Investigations On Pulmonary Hypertension Syndrome In Meat Type- Chickens, Khaloud Alzahrani

Graduate Theses and Dissertations

This dissertation presents a collection of studies that investigate the genetic and epigenetic associations to ascites phenotype in broiler chickens. Ascites is a significant metabolic disease associated with fast-growing meat-type chickens (broilers) and is a terminal result of pulmonary hypertension syndrome PHS. It is a multi-factorial syndrome caused by interactions between genetic, physiological, environmental, and managemental factors. It was estimated that ascites accounts for losses of about US$1 billion annually worldwide and for over 25% of broilers mortality. Although traditional and molecular genetic methods in the selection and in performance improvements, has greatly reduced ascites frequency, yet it has not …

Impacts Of Genome And Nuclear Architecture On Molecular Evolution In Eukaryotes, Xyrus Maurer-Alcalá

Doctoral Dissertations

The traditional view of genomes suggests that they are static entities changing slowly in sequence and structure through time (e.g. evolving over geological time-scales). This outdated view has been challenged as our understanding of the dynamic nature of genomes has increased. Changes in DNA content (i.e. polyploidy) are common to specific life-cycle stages in a variety of eukaryotes, as are changes in genome content itself. These dramatic genomic changes include chromosomal deletions (i.e. paternal chromosome deletion in insects; Goday and Esteban 2001; Ross, et al. 2010), developmentally regulated genome rearrangements (e.g. the V(D)J system in adaptive immunity in mammals; Schatz …

Chromatin Accessibility Dynamics In The Arabidopsis Root Epidermis And Endodermis During Cold Acclimation, Shawn Hoogstra

Electronic Thesis and Dissertation Repository

Understanding cell-type specific transcriptional responses to environmental conditions is limited by a lack of knowledge of transcriptional control due to epigenetic dynamics. Additionally, cell-type analyses are limited by difficulties in applying current technologies to single cell-types. A novel DNase-seq protocol and analysis procedure, deemed DNase-DTS, was developed to identify DHSs in the Arabidopsis epidermis and endodermis under control and cold acclimation conditions. Results identified thousands of DHSs within each cell-type and experimental condition. DHSs showed strong association to gene expression, DNA methylation, and histone modifications. A priori mapping of existing DNA binding motifs within accessible genes and the cold C-repeat/dehydration …

Multiple Testing Correction With Repeated Correlated Outcomes: Applications To Epigenetics, Katie Leap

Masters Theses

Epigenetic changes (specifically DNA methylation) have been associated with adverse health outcomes; however, unlike genetic markers that are fixed over the lifetime of an individual, methylation can change. Given that there are a large number of methylation sites, measuring them repeatedly introduces multiple testing problems beyond those that exist in a static genetic context. Using simulations of epigenetic data, we considered different methods of controlling the false discovery rate. We considered several underlying associations between an exposure and methylation over time.

We found that testing each site with a linear mixed effects model and then controlling the false discovery rate …

Transcriptomic And Epigenetic Responses To Environmental Stress In Marine Bivalves With A Focus On Harmful Algal Blooms, Maria Victoria Suarez Ulloa

FIU Electronic Theses and Dissertations

Global change poses new threats for life in the oceans forcing marine organisms to respond through molecular acclimatory and adaptive strategies. Although bivalve molluscs are particularly tolerant and resilient to environmental stress, they must now face the challenge of more frequent and severe Harmful Algal Blooms (HABs) episodes. These massive outbreaks of microalgae produce toxins that accumulate in the tissues of these filter-feeder organisms, causing changes in their gene expression profiles, which in turn modify their phenotype in order to maintain homeostasis. Such modifications in gene expression are modulated by epigenetic mechanisms elicited by specific environmental stimuli, laying the foundations …

Epigenetic Regulation Of Lymphocyte Development And Transformation, Yue Huang

Arts & Sciences Electronic Theses and Dissertations

Cell identity and function rely on intricately controlled programs of gene regulation, alterations of which underlie many diseases, including cancer. Epigenetic analyses of normal and diseased cells have started to elucidate different facets of epigenetic mechanisms for gene regulation. These include changes in nucleosome density, histone modifications, factor binding and chromosomal architecture. All of these aspects contribute to the activities of regulatory elements conferring promoter, enhancer and insulator functions and the cis-regulatory circuits formed by these elements. Despite this progress, an urgent need remains to profile these features and to study how they cooperatively function in normal and pathogenic settings. …

Dynamic Regulation Of Dna Demethylation And Rna-Directed Dna Methylation In Arabidopsis, Kai Tang

Open Access Dissertations

DNA methylation is an important epigenetic mark present in many eukaryotes, and is involved in many crucial biological processes, such as gene imprinting, regulation of gene expression, and genome stability. Proper genomic DNA methylation patterns are achieved through the concerted action of DNA methylation and demethylation pathways. In the model plant species Arabidopsis thaliana, ROS1 (REPRESSOR OF SILENCING 1) is one of the DNA demethylases and the key component in the demethylation pathway. Dysfunction of ROS1 leads to increase in DNA methylation level at thousands of genomic loci. However, the features of ROS1 targets are not well understood. In the …

Understanding Ten-Eleven Translocation-2 In Hematological And Nervous Systems, Feng Pan

FIU Electronic Theses and Dissertations

I proposed the study of two distinct aspects of Ten-Eleven Translocation 2 (TET2) protein for understanding specific functions in different body systems.

In Part I, I characterized the molecular mechanisms of Tet2 in the hematological system. As the second member of Ten-Eleven Translocation protein family, TET2 is frequently mutated in leukemic patients. Previous studies have shown that the TET2 mutations frequently occur in 20% myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN), 10% T-cell lymphoma leukemia and 2% B-cell lymphoma leukemia. Genetic mouse models also display distinct phenotypes of various types of hematological malignancies. I performed 5-hydroxymethylcytosine (5hmC) chromatin immunoprecipitation sequencing (ChIP-Seq) and RNA …

Methods For Integrative Analysis Of Genomic Data, Paul Manser

Theses and Dissertations

In recent years, the development of new genomic technologies has allowed for the investigation of many regulatory epigenetic marks besides expression levels, on a genome-wide scale. As the price for these technologies continues to decrease, study sizes will not only increase, but several different assays are beginning to be used for the same samples. It is therefore desirable to develop statistical methods to integrate multiple data types that can handle the increased computational burden of incorporating large data sets. Furthermore, it is important to develop sound quality control and normalization methods as technical errors can compound when integrating multiple genomic …

Genome-Wide Profiling Unveils Criticial Functions Of P53 In Human Embryonic Stem Cells, Kadir C. Akdemir

Dissertations & Theses (Open Access)

Embryonic stem cells (ESCs) possess two unique characteristics: infinite self-renewal and the potential to differentiate into almost every cell type (pluripotency). Recently, global expression analyses of metastatic breast and lung cancers revealed an ESC-like expression program or signature, specifically for cancers that are mutant for p53 function. Surprisingly, although p53 is widely recognized as the guardian of the genome, due to its roles in cell cycle checkpoints, programmed cell death or senescence, relatively little is known about p53 functions in normal cells, especially in ESCs. My hypothesis is that p53 has specific transcription regulatory functions in human ESCs (hESCs) that …