Life Sciences Commons^™

Uncovering Dual Roles For Perk Signaling During Experimentally Induced Pancreatitis, Elena Fazio

Electronic Thesis and Dissertation Repository

Pancreatitis is characterized by inappropriate activation of digestive enzyme

precursors, or zymogens, local and systemic inflammation, dysregulation of

cellular calcium (Ca2+), and induction of the unfolded protein response (UPR).

The UPR consists of three distinct pathways all of which are activated during

pancreatitis. However, the molecular roles of each remain unclear. The

protein kinase RNA (PKR)-like ER kinase (PERK) pathway reduces general

protein translation by phosphorylating eIF2!, and is activated within minutes

of initiating pancreatic damage. Microarray analysis carried out by our lab

revealed robust upregulation of the PERK pathways members Activating

Transcription Factor (ATF) 3 and stanniocalcin (STC) 2. …

The Role Of Nodal In The Regulation Of Bi-Potential Trophoblast Progenitor Cells, Alia Cloutier-Bosworth

Electronic Thesis and Dissertation Repository

The human placenta develops from highly proliferative and phenotypically plastic cells called trophoblasts. Bi-potential trophoblast stem cells differentiate into the villous pathway to form the syncytiotrophoblast layer and the extravillous trophoblast (EVT). The HTR-8/SVneo cell line is widely used to study trophoblast biology. These cells variably express villous-specific or EVT-specific genes depending on conditions. Such phenotypic plasticity is indicative of a bi-potential cytotrophoblast progenitor. Preliminary work has shown that similar to progenitors in situ, a subpopulation of HTR-8/SVneo cells expresses a6b4 integrin. This a6b4^high subset exhibits enhanced clonogenicity and differentiation capacity. This cell line also expresses Nodal, a …

Placental Insufficiency Resulting In Fetal Growth Restriction Alters Synaptic Development And Neuronal Myelination In Guinea Pigs At Term, Karolina Piorkowska

Electronic Thesis and Dissertation Repository

Aberrant neuronal connectivity in utero may underlie the association between fetal growth restriction (FGR) and increased risk for later cognitive disorders and encephalopathy. This study examines changes in synaptic development and myelination focussing on the hippocampus using a guinea pig model of placental insufficiency. Placental insufficiency was induced at mid-gestation by uterine artery ligation or cauterization which produced fetuses with a range of body weight and proportion at term. Synaptic markers, synaptophysin and synaptopodin, were decreased in FGR animals suggesting fewer synapses were formed and furthermore that fewer synapses matured with symmetrical growth restriction when compared to appropriate for gestational …

Create The Scene And Watch The Show Unfold: Following Vegetative To Embryonic Developmental Transitions By Over-Expressing Lec2 In Leaves Of Arabidopsis Thaliana, Mistianne Feeney

Electronic Thesis and Dissertation Repository

During seed development, the lytic vacuole (LV) is replaced by a protein storage vacuole (PSV) which specializes in accumulating seed storage proteins (SSPs). As seed protein reserves are mobilized upon germination, the PSV is once again replaced by the LV which takes on different roles in vegetative tissues. Cellular events occurring during these developmental transitions are not well understood, particularly, the transition between vacuole types. This research investigates whether PSVs can exist in leaves. To study vacuole transitions in leaves, an Arabidopsis thaliana line over-expressing the LEAFY COTYLEDON2 (LEC2) transcription factor was used. LEC2 is a master regulator of embryogenesis …

Identification And Characterization Of The Arabidopsis Homolog Of The Yeast Trex-2 Complex, Gang Tian

Electronic Thesis and Dissertation Repository

Nuclear pore complexes (NPCs) are vital to nuclear-cytoplasmic communication in eukaryotes. The yeast Thp1-Sac3-Cdc31-Sus1 complex, also known as the TREX-2 complex, is anchored to the NPC via the nucleoporin Nup1, and is essential for mRNA export. In this study, the Arabidopsis homolog of the yeast TREX-2 complex was discovered. Physical and functional evidence support the identification of the Arabidopsis orthologs of the yeast Thp1 and Nup1. Of three Sac3 Arabidopsis homologs, two are putative TREX-2 components. Surprisingly, none are required for mRNA export as is the yeast Sac3. Physical association with TREX-2 was observed for the two Cdc31 homologs, but …

Modulation Of G Protein-Coupled Receptor Intracellular Trafficking And Signal Transduction, Jessica L. Esseltine

Electronic Thesis and Dissertation Repository

The seven transmembrane-spanning G Protein-coupled Receptor (GPCR) super family is the largest family of cell-surface receptors, comprising greater than 650 members. GPCRs represent the primary targets of most therapeutic drugs. Desensitization, endocytosis and recycling are major mechanisms of receptor regulation and intracellular trafficking of GPCRs is linked to the Rab family of small G proteins. In the present study, we examined whether multiple Rab GTPase regulate receptor trafficking through endosomal cellular compartments as a consequence of their direct association with GPCRs. We find that Rab4, Rab7 and Rab11 all bind to the last 10 amino acid residues of the angiotensin …

Mass Spectrometry-Based Proteomics Analysis Of The Matrix Microenvironment In Pluripotent Stem Cell Culture, Christopher Hughes

Electronic Thesis and Dissertation Repository

The stem cell microenvironment contains soluble factors, support cells, and components of the extracellular matrix (ECM) that combine to effect cellular behavior. Mass spectrometry based proteomics offers the opportunity to directly assay components of extracellular microenvironments, thereby providing a sensitive means for obtaining insight into the stem cell niche. In this study we present the generation and analysis of human embryonic stem cell (hESC) and human induced pluripotent stem cell (hiPSC) matrix microenvironments using an MS-based proteomics approach.

One of the primary limitations in the proteomics analysis of hESCs and hiPSCs is the reproducible generation of sufficient cell numbers amenable …

The Role Of Pex11-Beta In Peroxisome Biogenesis, Intracellular Relationship To Reactive Oxygen Species Levels And Redox-Sensitive Cell Signaling, Mark A. Fox

Electronic Thesis and Dissertation Repository

Peroxisomes are organelles whose roles in fatty acid metabolism and reactive oxygen species (ROS) elimination have contributed much attention in understanding their origin and biogenesis. Many studies have shown that de novo peroxisome biogenesis is an important regulatory process, while yeast studies suggest that total peroxisome numbers are in part regulated by proteins such as Pex11, which can facilitate the division of existing peroxisomes. Although de novo biogenesis and divisions are likely important mechanisms to peroxisome functioning, the regulation of peroxisome numbers during embryonic development is poorly understood. Peroxisome number and function are particularly crucial in oviparous animals such as …

Molecular Mechanisms Of Cell Migration Inhibition By Synthetic Triterpenoids, Ciric Chi Wing To

Electronic Thesis and Dissertation Repository

Cell migration is an important mediator of cancer metastasis and invasion, which is responsible for 90% of cancer-related premature deaths in Canada. Synthetic triterpenoids are a class of promising anti-cancer compounds that have shown considerable efficacy in targeting various cellular functions including apoptosis, growth, inflammation and cytoprotection in both cell culture and animal tumor models. However, their effect on cell migration, an important event in metastasis, remains poorly understood. This thesis focuses on deciphering the molecular mechanisms whereby the synthetic triterpenoids affect cell migration. I observed that the imidazolide and methyl ester derivatives of the synthetic triterpenoid, 2-cyano-3,12-dioxooleana-1,9-dien-28-oic aic acid …

The Developmental And Adaptive Role Of Mitogen Activated Protein Kinase Pathways During Preimplantation Development, Christine E. Bell

Electronic Thesis and Dissertation Repository

The preimplantation period of development represents the highest interval of embryonic loss throughout pregnancy. It is therefore imperative that we elucidate the mechanisms involved in regulating preimplantation embryonic responses to stress and that govern development. The MAPK pathways are involved in both responding to environmental stress and regulation of development throughout embryogenesis, and are therefore good candidates to study the mechanisms involved in preimplantation embryonic adaptation to stress and development. The preimplantation embryo culminates in the development of a fluid filled structure called the blastocyst. It is at this stage the first differentiation events occur and the trophectoderm (TE), which …

The Intracellular Behaviour Of Burkholderia Cenocepacia In Murine Macrophages, Jennifer S. Tolman

Electronic Thesis and Dissertation Repository

Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in cystic fibrosis and other immunocompromised patients. The bacterium survives within macrophages by interfering with typical endocytic trafficking, resulting in delayed maturation of a B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia alters gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation. Furthermore, we hypothesize that specialized bacterial secretion systems are involved in the interactions between intracellular bacteria and macrophages. In this work, we characterize later-stage infection of macrophages by B. cenocepacia, showing replication within an acidified endosomal compartment suggestive of a phagolysosome. …

Brassinosteroid-Mediated Stress Tolerance In Arabidopsis Thaliana, Tawhidur Rahman

Electronic Thesis and Dissertation Repository

Brassinosteroids (BRs) are a group of steroidal plant hormones that are essential for proper plant development and also promote stress tolerance. Without BRs, plants are dwarfs and infertile. To understand the molecular mechanisms underlying BR-mediated stress tolerance, global gene expression analysis of untreated and 24-epibrassinolide (EBR)-treated Arabidopsis thaliana seedlings under non-stress and heat stress (HS) conditions was carried out. Microarray data analysis indicated that stress-related genes were predominant within the EBR up-regulated gene data set. Furthermore, several of these genes were abscisic acid (ABA) and jasmonic acid (JA) related. Measurements of endogenous hormones showed significant increases in the levels ABA …

Metastatic Disease: Interactions Between Tumor Cells And Host Environment During Cancer Cell Spread, Jennifer M. Maclean

Electronic Thesis and Dissertation Repository

Tumor and metastasis formation are not cell autonomous phenomena, but rather an evolution of disease within and responding to the host environment. Metastatic spread from a primary tumor occurs as a result of a complex interplay between tumor cells and the host, wherein tumor cells must escape the primary tumor, enter the host vasculature, travel to and arrest in a distant tissue and survive and grow in that new organ. It is known that cells that progress through these stages must both escape and exploit host systems, yet the mechanisms used are not fully understood. Therefore, the goal of this …

The Regulation Of Cell Division And Neurogenesis By The Chromatin Remodeling Protein Atrx, Kieran L. Ritchie

Electronic Thesis and Dissertation Repository

Mutations in the ATRX gene cause alpha thalassemia mental retardation X-linked syndrome (ATR-X). Individuals with ATR-X syndrome show a broad range of developmental abnormalities including severe cognitive, behavioural, and learning deficits, seizures, and microcephaly, indicating that ATRX is essential for normal development of the central nervous system. Conditional inactivation of Atrx in the developing mouse forebrain leads to a reduction in cerebral cortical size, elevated levels of p53-dependent neuronal apoptosis, and dysgenesis of certain subcortical structures, including the hippocampus and dentate gyrus, confirming a requirement for Atrx in mammalian brain development. The mammalian ATRX gene encodes a member of the …

The Effects Of Superovulation And Embryo Culture On Genomic Imprinting In A Mouse Model System, Brenna A. M. Velker

Electronic Thesis and Dissertation Repository

Genomic imprinting is a specialized transcriptional mechanism resulting in the unequal expression of alleles based on their parent-of-origin. Imprinted genes are critical for embryonic and fetal development and their dysregulation is linked to a group of human diseases called imprinting disorders, including Beckwith-Wiedemann Syndrome, Angelman Syndrome and Silver-Russell Syndrome. Two critical phases of genomic imprinting exist. The acquisition phase occurs in developing germ cells, asynchronously for different imprinted loci, while the maintenance phase takes place during preimplantation development, while the rest of the genome is undergoing demethylation. Increased frequencies of human imprinting disorders are observed in children following the use …

Regional Specification Of The Xenopus Lateral Plate Mesoderm, Steven J. Deimling

Electronic Thesis and Dissertation Repository

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Successful patterning of the embryo, from establishing the three primary axes to the regional specification of tissue progenitors is essential to generating a viable embryo. The three germ layers in the early embryo undergo patterning through slightly different mechanisms. The tissue of interest to this study is the lateral plate mesoderm (LPM), which will give rise to the lineages of the cardiovascular system and is essential for regional specification of adjacent germ layers. …

The Life Cycle Of Pannexins: Trafficking, Cell Surface Dynamics, Turnover And Degradation, Ruchi Gehi

Electronic Thesis and Dissertation Repository

Pannexins (Panxs) are a recently identified family of channel-forming glycoproteins, comprised of three members: Panx1, Panx2 and Panx3. Panxs were classified as gap junction (GJ) proteins based on their shared sequence homology to the invertebrate GJ protein, innexins. While no sequence homology exist between Panxs and the GJ proteins, connexins (Cxs), they share similar topology with four transmembrane domains, two extracellular loops, an intracellular loop and cytoplasmic exposed amino and carboxy terminal tails. In this study, we investigated if Panx1 and Panx3 exhibit unique or shared properties of cell surface delivery, mobility, cytoskeletal dependency, internalization and degradation, to the well …

The Roles Of Nitric Oxide Synthases (Nos) In Endochondral Bone Formation, Qian Yan

Electronic Thesis and Dissertation Repository

Longitudinal growth of endochondral bones is controlled by the cartilage growth plate. Chondrocyte proliferation and hypertrophy, vascular invasion, formation of ossification centers and cartilage replacement by bone tissue are all important processes required for normal growth. These biological processes have to be tightly regulated or disturbances will lead to skeletal diseases. A large number of genes, growth factors and hormones have been implicated in the regulation of growth plate biology, however, less is known about the intracellular signaling pathways involved. Nitric oxide (NO) has been identified as a regulator of cellular proliferation, differentiation, migration, survival and metabolism in multiple cell …

Regulation Of Dna Damage Processing By Covalent Modification Of Thymine Dna Glycosylase, Ryan D. Mohan

Electronic Thesis and Dissertation Repository

Thymine DNA glycosylase (TDG) is an essential DNA repair enzyme mediating excision of uracil and thymine mispaired with guanine within CpG contexts. Unrepaired, these lesions result in G:C to A:T transitions which are major contributors to genome instability. Interestingly, TDG interacts functionally with transcriptional regulators and participates in directed cytosine demethylation at promoters. TDG is subject to multiple post-translational modifications (PTM) and we undertook an analysis of how these regulate TDG function. Initially, we examined TDG regulation by small ubiquitin-like modifier (SUMO) and identified a novel SUMO binding motif (SBM1, residues 144-148). We hypothesized that SBM1, along with SBM2 (319-322), …