Cell and Developmental Biology Commons^™

Connections Between Mechanosensitive Ion Channel Msl10 And Er-Plasma Membrane Contact Sites, Jennette Marie Codjoe

Arts & Sciences Electronic Theses and Dissertations

Mechanosensitive (MS) ion channels are an evolutionarily conserved way for cells to sense mechanical forces and transduce them into ionic signals. A plasma membrane-localized MS channel from Arabidopsis thaliana, MscS-Like (MSL)10, senses cell swelling and initiates a signaling cascade that triggers programmed cell death. Whereas the channel properties of MSL10 have been well studied, how MSL10 signals remains largely unknown. I worked collaboratively to show that important lesions for cell death signaling in the cytosolic N- and C-terminal domains of MSL10 interact genetically. I also helped show that ionic flux through MSL10 is dispensable for signaling, which suggested that MSL10 …

The Role Of The Neurodevelopmental Disorder Gene Myt1l In Mammalian Brain Development, Jiayang Chen

Arts & Sciences Electronic Theses and Dissertations

Recent human genetic studies have associated mutations in a gene called Myelin Transcription Factor 1 Like (MYT1L) with neurodevelopmental disorders (NDDs). Patients with MYT1L loss of function (LoF) mutations (MYT1L Syndrome patients) demonstrate shared symptoms such as microcephaly, attention deficit and hyperactivity disorder (ADHD), and obesity. Despite prior studies showing MYT1L overexpression facilitates neuronal differentiation in vitro, its functions in vivo, especially in the mammalian brain, and how its mutation leads to human disease pathology remains poorly understood. Here, I established the first mouse model of MYT1L Syndrome mimicking a patient specific LoF mutation. I found mice with Myt1l heterozygous …

Exploring Β-Cell Function And Heterogeneity In Obese Sm/J Mice, Mario Alejandro Miranda

Arts & Sciences Electronic Theses and Dissertations

Pancreatic β-cells perform glucose-stimulated insulin secretion, a process required to maintain systemic glucose homeostasis. Obesity promotes glycemic and inflammatory stress, causing β-cell death and dysfunction, resulting in diabetes. Efforts to improve β-cell function in obesity have been hampered by observations that β-cells are highly heterogeneous, varying in morphology, function, and gene expression. There is great need to understand the breadth of β-cell heterogeneity in health and obesity to improve diabetic therapies.High fat-fed SM/J mice spontaneously transition from hyperglycemic-obese to normoglycemic-obese with age, providing a unique opportunity to study β-cell adaptation. Here, we show that as they resolve hyperglycemia, obese SM/J …

Discovery Of Sex Differences In Response To P53 Loss And Gain-Of-Function In Glioblastoma, Nathan Cuyle Rockwell

Arts & Sciences Electronic Theses and Dissertations

The tumor suppressor TP53 (p53) is the most frequently mutated gene in cancer and among the most mutated genes in brain cancer. Functionally, p53 is a transcription factor that, when activated by an array of stress stimuli, regulates a complex transcriptional program that contributes to a variety of antiproliferative pathways. The loss of p53 function (LOF), either through mutation, deletion, or inhibition by alterations in the proteins that regulate p53, removes an essential barrier to the unfettered proliferation and genomic instability that drive transformation. Unlike most tumor suppressors, many p53 mutations are missense mutations that lead to stable expression of …

Regulation Of Genome Architecture By Chromatin Remodeling In The Brain, Jared Vega Goodman

Arts & Sciences Electronic Theses and Dissertations

Brain development requires exquisite control of gene expression to establish and refine the proper circuitry of the nervous system. Gene expression control is under the purview of several cellular processes, including chromatin regulation in the form of DNA modification, histone modification, and nucleosome remodeling. Chromatin remodeling enzymes are the major effectors of nucleosome remodeling. These enzymes are clearly involved in brain development – mutations in chromatin remodeling enzymes are likely causative for neurodevelopmental disorders of cognition. Chromatin remodeling enzymes have discrete molecular functions and binding profiles and similarly control distinct phases of nervous system maturation. Chd4 is a Chd family …

The Phylogeography Of Rare Central Tennessee Glade Endemics Trifolium Calcaricum And Viola Egglestonii, Rachel Ann Lyman

Arts & Sciences Electronic Theses and Dissertations

Endemic species are range-restricted to a particular type of habitat and generally occur in a few small populations. Often endemic species are threatened or endangered due to their geographic isolation and limited habitat breadth. Despite the fact that understanding factors that may have shaped the evolutionary history of a species with a narrow distribution can provide important insights for their management and conservation, little is known about the historical forces that gave rise to many endemic species. Endemic species can arise because of factors such as variation in climate, geographic barriers, and habitat specificity, or the combination of several of …

Comprehensive Characterization Of The Genetic And Neoantigen Landscapes Of Follicular Lymphoma Patients Supports The Feasibility Of Personalized Cancer Vaccine Treatments, Cody Alexander Ramirez

Arts & Sciences Electronic Theses and Dissertations

Follicular lymphoma (FL) is the most common indolent non-Hodgkin’s lymphoma; however, it remains incurable with conventional therapies and is poorly responsive to checkpoint blockade. FL arises from B-lymphocytes and develops slowly (and often asymptomatically). A major research focus has been on how to avoid chemotherapy treatments, to limit the potential development of treatment-related side effects, and the risk of therapy-related second cancers. FL also carries an approximately 30% lifetime risk of transforming from an iNHL to more destructive lymphomas, which are associated with poorer prognosis. The most common transformation results in diffuse large B-cell lymphoma (DLBCL). However, many patients may …

Transcriptional Control Of Dendritic Cell Function And Development, David Alexander Anderson Iii

Arts & Sciences Electronic Theses and Dissertations

Dendritic cells (DCs) are innate immune cells of the myeloid lineage that are specialized at pathogen recognition, cytokine production, and antigen presentation. Their functions and developmental pathways are largely conserved between mice and humans and mice. The DC lineage is composed of two major subsets, known as plasmacytoid DCs (pDCs) and classical DCs (cDCs). Research conducted to date suggests that the function of pDCs, limited to viral antigen recognition and type I interferon production, can be compensated by other immune cell lineages. On the other hand, there is a consensus that diversified subsets cDCs in mice and humans are essential …

The Genetic Basis Of Adaptation To Environmental Stress In Two Grass Genomic Model Systems, David Mitchell Goad

Arts & Sciences Electronic Theses and Dissertations

Plants are exposed to a wide variety of environmental stress in the wild and have developed an equally diverse set of adaptations to tolerate them. The evolutionary processes that have led to this functional diversification, and the specific genes and physiological mechanisms involved, are of immense interest to both evolutionary biologists and crop breeders. In this dissertation I investigate adaptation to different types of environmental stress in two economically important grass species, seashore paspalum (Paspalum vaginatum Sw.) and rice (Oryza sativa L.).

Seashore paspalum is a halophytic turfgrass that occupies habitats which can dramatically differ in salt concentration. Populations may …

Single-Cell Resolution Mechanistic Analyses Of Direct Lineage Reprogramming, Chuner Guo

Arts & Sciences Electronic Theses and Dissertations

End-stage organ failures remain a clinical challenge with an unmet need for medical therapies, with transplantation often being the only curative option. Despite advances in transplantation outcomes, organ shortage continues to limit the availability of cures to patients in need. The direct lineage reprogramming of one cell type to another is a promising avenue for therapy with the following advantages: (1) patient-specific cell sources, (2) direct conversion without reverting to pluripotency and the associated risk of teratoma formation, and (3) utilization of the cell type responsible for fibrotic scar formation for the engineering towards the desired cell fate. Nonetheless, many …

Fgf20 In Olfactory System And Cochlea Development, Lu Morgan Yang

Arts & Sciences Electronic Theses and Dissertations

The olfactory epithelium (OE) is a neurosensory organ required for the sense of smell. Turbinates, bony projections from the nasal cavity wall, increase the surface area within the nasal cavity lined by the OE. We identified a population of OE progenitor cells that expand horizontally during development to populate all lineages of the mature OE and increase OE surface area. We show that these Fgf20-positive, epithelium-spanning progenitor (FEP) cells are responsive to Wnt/β-Catenin signaling. Wnt signaling suppresses FEP cell differentiation into OE basal progenitors and their progeny, and positively regulates Fgf20 expression. We further show that FGF20 signals to the …

Transcriptional And Epigenetic Regulation Of Cerebellar Development And Function, Naveen C. Reddy

Arts & Sciences Electronic Theses and Dissertations

Precise control of gene expression is essential for neural development and function. This control is regulated by the interplay of chromatin remodelers and transcription factors (TFs). To better understand these mechanisms involved in gene regulation, we pursue two questions: 1) what are the roles of the chromatin remodeler CHD7 in cerebellar development and 2) what are the roles of the MEF2 TF family in cerebellar function. CHD7 mutations are causative for CHARGE syndrome, a heterogeneous disorder affecting many organ systems, occurring in 1:10,000 newborns. Recent MRI studies have identified cerebellar hypoplasia and foliation defects in a large portion of CHARGE …

An Evolving Epigenome That Determines Tissue And Cell Specificity, Renee Louise Sears

Arts & Sciences Electronic Theses and Dissertations

Understanding the mechanisms driving phenotypic variation is a major goal of biology that unifies classical genetics with the emerging fields of genomics and epigenomics. Human and mouse share over 90% of genes and global tissue-specific patterns of expression are maintained between the species. Thus, it is hypothesized that gene expression is influenced through distinctive regulation among species in order to account for the unmistakable phenotypic divergence. DNA methylation, histone modifications, open chromatin patterns, transcription factor binding, and other epigenetic factors are all associated with shaping, maintaining, and repressing regulatory regions which in turn coordinate gene expression. It is vital to …

A Noncanonical Function Of The Telomerase Rna Component In Human Embryonic Stem Cells, Kirsten Ann Brenner

Arts & Sciences Electronic Theses and Dissertations

Telomeres are stretches of TTAGGG nucleotide repeats located at the ends of linear chromosomes that shorten with progressive cell division and prevent genomic instability at the cost of limiting a cell’s capacity to proliferate. This limitation can be overcome by telomerase, a ribonucleoprotein complex that elongates telomeres via reverse-transcription of the template telomerase RNA component (TERC). Recent studies have reported potential functions of TERC outside of its role in telomere maintenance. These noncanonical functions of TERC are however poorly defined, and the molecular mechanisms and biological relevance behind such functions remain elusive. Here, we generated conditional TERC knock-out human embryonic …

From Single Cells To Human Disease: High-Resolution Phenotyping Of Male Infertility Models Using Single-Cell Rna Sequencing, Min Jung

Arts & Sciences Electronic Theses and Dissertations

Male infertility is a complex disease that can result in significant emotional distress and treatment costs. Globally, male infertility affects 7% of males, and while its incidence is rising, its etiology remains elusive. In order to improve patient care, it is critical to identify the nature of spermatogenic failure in as many men as possible. The extensive cellular heterogeneity of testis has limited the application of bulk expression measurements to capture crucial information to dissect molecular mechanisms of defects in the infertile patients. Thus, the application of single-cell RNA-sequencing on male germ cells provides an amazing new set of scientific …

Exploring Infant Leukemia Through Exome Sequencing And An In Vitro Model Of Hematopoietic Development, Mark Cannon Valentine

Arts & Sciences Electronic Theses and Dissertations

Cancer is a heterogeneous disease with myriad causes and outcomes. Many of the cancers that occur in adult populations have become increasingly well characterized with the advent of affordable high-throughput sequencing. These studies have revealed that cancer is largely a disease of somatic mutation in the adult population. In strong contrast to this, childhood cancers have an exceedingly low rate of somatic mutation. At the extreme end of this spectrum is Infant Leukemia (IL). Sequencing of IL has revealed that these tumors frequently have one or fewer somatic SNP. In the absence of a somatic explanation for IL, many other …

Genetic Basis Of Thermal Divergence In Saccharomyces Species, Xueying C. Li

Arts & Sciences Electronic Theses and Dissertations

The genetic architecture of phenotypic divergence is a central question in evolutionary biology. Genetic architecture is impacted by whether evolution occurs through accumulation of many small-effect or a few large-effect changes, the relative contribution of coding and cis-regulatory changes, and the prevalence of epistatic effects. Our empirical understanding of the genetic basis of evolutionary change remains incomplete, largely because reproductive barriers limit genetic analysis to those phenotypes that distinguish closely related species. In this dissertation, I use hybrid genetic analysis to examine the basis of thermal divergence between two post-zygotically isolated species, Saccharomyces cerevisiae and S. uvarum. S. cerevisiae is …

The Role Of Mesenchymal Stromal Cells And Classical Dendritic Cells In The Maintenance And Regulation Of The Bone Marrow Niche, Jingzhu Zhang

Arts & Sciences Electronic Theses and Dissertations

The bone marrow niche is an important microenvironment for the regulation of normal and malignant hematopoiesis. The first discovered niche component is mesenchymal stromal cells, which are the major source for the production and secretion of multiple niche factors. Mesenchymal stromal cells are heterogeneous and various transgenes have been used to target non-identical but overlapping subpopulations. To further characterize the heterogeneity of mesenchymal stromal cells, we tested the targeting specificity of three tissue-specific Cre-recombinase transgenes. We show that in addition to osteoblasts, Ocn-Cre targets a majority of Cxcl12-abundant reticular (CAR) cells and arteriolar pericytes. Surprisingly, Dmp1-Cre also targets a subset …

The Role Of Actr10 In Nervous System Development And Disease, Amy Herbert

Arts & Sciences Electronic Theses and Dissertations

The vertebrate nervous system requires myelinating glia for the fast propagation of action potentials, as well as for vital trophic support to axons. Myelinating glia produce myelin, which is a lipid-rich, multi-lamellar sheath that surrounds axons and allows for rapid electrical signaling. In the central nervous system (CNS), myelin is produced by oligodendrocytes, while in the peripheral nervous system (PNS), Schwann cells perform this function. Although glia have historically been understudied compared to neurons, recent research has uncovered critical roles for glia in nervous system development and disease. Disruption to myelin or to the glial cells that generate myelin can …

Mechanism Of Gene Regulation By Coding Polya Tracks, Laura Lea Arthur

Arts & Sciences Electronic Theses and Dissertations

Regulation of gene expression is essential for cellular development and survival. The great variety and complexity of regulatory mechanisms underscores this fact. Messenger RNA stability and translational efficiency are often key determinants of gene expression. mRNA surveillance pathways, discovered for their role in degradation of aberrant mRNA, are now known to be instrumental in the regulation of physiologically correct mRNA stability. Thus, the study of cis elements in a transcript that can induce mRNA surveillance pathways has become an area of particular interest.

Here I report on the mechanism of gene regulation by coding polyA tracks, defined as a sequence …

Analysis Of Argonaute-Small Rna-Transcription Factor Circuits Controlling Leaf Development, John Steen Hoyer

Arts & Sciences Electronic Theses and Dissertations

Experimental studies of plant development have yielded many insights into gene regulation, revealing interactions between core transcriptional and post-transcriptional regulatory pathways present in all land plants. This work describes a direct connection between the three main small RNA-transcription factor circuits controlling leaf shape dynamics in the reference plant Arabidopsis thaliana. We used a high-throughput yeast 1-hybrid platform to identify factors directly binding the promoter of the highly specialized ARGONAUTE7 silencing factor. Two groups of developmentally significant microRNA-targeted transcription factors were the clearest hits from these screens, but transgenic complementation analysis indicated that their binding sites make only a small contribution …

Factors That Contribute To De Novo Protein Misfolding And Prion Formation In Saccharomyces Cerevisiae, Kathryn Morgan Keefer

Arts & Sciences Electronic Theses and Dissertations

Protein misfolding is a common phenomenon that can have severe consequences on cellular and organismal health. Despite this, the causes of protein misfolding remain poorly understood. Prions are a class of proteins that, when misfolded, can convert other molecules into a heritable, non-native conformation. The yeast Saccharomyces cerevisiae naturally harbors several diverse prion-forming proteins; thus, it is an ideal model with which to investigate the factors that influence misfolding and aggregation.This thesis utilizes the yeast prions [PSI+] and [RNQ+] to investigate two distinct steps of the protein misfolding pathway: interactions with chaperones and their cofactors, and heterologous templating by other …

Genetic And Genomic Dissections Of Myelinating Glial Cell Development, Breanne Leigh Harty

Arts & Sciences Electronic Theses and Dissertations

Myelin is a multilamellar sheath made by specialized glial cells that iteratively spiral and compact their plasma membranes around axon segments. In vertebrate nervous systems, myelination facilitates rapid action propagation and provides trophic support critical for neuronal survival. In the central nervous system (CNS), oligodendrocytes (OLs) extend many processes to simultaneously ensheath multiple axons, while in the peripheral nervous system (PNS), myelinating Schwann cells (SCs) pair 1:1 with a single axon segment. Elaboration of the myelin sheath is one of the most exquisite and complex examples of massive coordinated cellular shape changes in the vertebrate nervous system. Furthermore, the importance …