Life Sciences Commons^™

Chromatin Regulation By Rb-Interacting Proteins In Cellular Immune Functions, Seung June Kim

Electronic Thesis and Dissertation Repository

The retinoblastoma protein (RB) is historically known for its function in cell cycle control. However, mice carrying targeted Rb1 mutations have revealed that RB serves various non-cell cycle control roles. Notably, RB acts as a scaffold that recruits chromatin regulatory proteins, condensin II and enhancer of zeste homolog 2 (EZH2). These complexes protect the genome integrity through maintaining proper chromosome condensation, long range contacts, and transcriptionally repressive histone modification. This thesis explores the mechanistic links that regulate such RB-condensin II complex or that are leveraged upon pharmacological inhibition of the RB-EZH2 complex. First, I identified potential phosphorylation sites in the …

Regulation Of Hedgehog And Wnt Signaling In Neural Differentiation Of P19 Embryonal Carcinoma Cells, Danielle Margaret Spice

Electronic Thesis and Dissertation Repository

The Hedgehog (Hh) and Wnt protein signaling pathways are essential in the differentiation of neurons and astrocytes. As there are many known and new players involved in regulating these pathways, the role of the regulators Suppressor of Fused (SUFU) and Never in Mitosis Kinase 2 (Nek2) have either not been previously reported or have not been thoroughly explored. To address this shortfall CRISPR gene editing was used to target SUFU and Nek2 in the mouse P19 embryonal carcinoma cell model of neural differentiation. Hh and Wnt signaling were explored in normal P19 neural differentiation, which occurs in the presence of …

Tracing The Fate Of Cytokeratin 19+ Cells During Beta Cell Regeneration Stimulated By Multipotent Stromal Cell-Secreted Effectors, Nazihah Rasiwala

Electronic Thesis and Dissertation Repository

Human bone marrow-derived multipotent stromal cells expanded under Wnt pathway stimulation secrete beta cell-regenerative factors collected as conditioned media (Wnt+ CdM). We used the cytokeratin 19 (CK19)-CreERT Rosa26-mTomato lineage tracing mouse to observe CK19+ cell conversion to insulin+ beta cells following intra-pancreatic injection of Wnt+ CdM. Tamoxifen treatment in mice induced labelling of CK19+ ductal and acinar cells with tdTomato and streptozotocin (50 mg/kg/day x 5 days) induced hyperglycemia. Injection of Wnt+ CdM preserved beta cell mass, reduced non-fasted blood glucose levels, and improved glucose tolerance over a 28-day period compared to controls. Insulin+/tdTomato+ cells in mice given Wnt+ CdM …

Rhamm As A Biomarker And Therapeutic Target In Triple-Negative Breast Cancer, Britney Messam

Electronic Thesis and Dissertation Repository

Triple-negative breast cancer (TNBC) is a heterogeneous group of tumours characterized by early metastases and poor prognosis. Discovering novel biomarkers and therapeutic targets is necessary to improve TNBC patient outcomes as resistance to chemotherapy, the main therapeutic approach for TNBC, is common. In my study, RHAMM promoted proliferation of TNBC MDA-MB-231 tumour cells. RHAMM expression increased sensitivity to doxorubicin (p=0.0002) and strongly increased sensitivity to the FDA-approved MEK1/2 inhibitor trametinib (p≤0.0001). Doxorubicin and trametinib selectively killed RHAMM^+/+ MDA-MB-231 tumour cells grown as co-cultures with RHAMM^-/- MDA-MB-231 tumour cells. RHAMM-loss or trametinib decreased phosphorylated ERK1/2 protein levels and …

Extrinsic And Intrinsic Factors Influencing Homeostasis And Repair In Oral Tissues, Georgia Nikoloudaki

Electronic Thesis and Dissertation Repository

The oral tissues, including gingiva and buccal mucosa, heal rapidly with minimal scar formation. Although in the oral cavity, the palatal mucosa is associated with excessive scarring in response to injury. In this thesis, first, I investigated the complex relationship between cells and their microenvironment using wound healing models in which extracellular matrix composition and mechanical stiffness affect cellular responses during acute wound repair. I also determined how intrinsic differences of cells recruited during healing contribute to wound resolution.

In Chapter 2, I first investigated cell-extrinsic factors, specifically the influence of the pro-fibrotic matricellular protein periostin on palatal healing. Using …

The Role Of Reactive Oxygen Species In The Accumulation Of Driver Mutations In B Cell Acute Lymphoblastic Leukemia, Mia P. Sams

Electronic Thesis and Dissertation Repository

B cell acute lymphoblastic leukemia (B-ALL) is the most prevalent type of cancer in young children and is associated with recurrent mutations and high levels of reactive oxygen species (ROS). The antioxidant N-acetylcysteine was tested for its ability to prolong lifespan of a mouse model of B-ALL and reduce frequency of mutations. Mice treated with 1g/L of N-acetylcysteine in drinking water were found to have delayed onset of B-ALL at 11 weeks of age and changes in gene expression relating to B cell development, calcium-apoptosis signaling, and pathways in cancer, although no differences in lifespan were observed. Tumours from treated …

Characterization Of Galectin-16 Expression And Function In Placental Cells, Jennifer Kaminker

Electronic Thesis and Dissertation Repository

The processes of cellular differentiation and apoptosis are critical for placental development. The galectin-16 gene (LGALS16) is associated with these processes in the placenta, but the mechanism by which it acts is poorly characterized. My bioinformatics analysis revealed that LGALS16 expression was limited to specific tissues including the placenta and identified multiple regulatory molecules (transcription factors and miRNAs), which could potentially control relevant transcriptional and post-transcriptional mechanisms. Considering the predominant expression of LGALS16 in placenta, I examined the expression, regulation, and function of LGALS16 in BeWo and JEG-3 cell lines representing in vitro models of trophoblast differentiation. In …

The Effect Of Maternal Immune Activation On Placental And Fetal Development In Rats, Kelly J. Baines

Electronic Thesis and Dissertation Repository

Development of the placenta and embryo is a highly orchestrated process that is vulnerable to changes in the in utero environment. Maternal immune activation (MIA) during pregnancy is a major risk factor for many obstetric complications and predisposes offspring to growth restriction as well as cognitive and neurobehavioral deficits; however, the mechanisms underlying these risks remain unknown. In this thesis, I aimed to determine the effect of MIA on development of the placenta and fetal brain. By administering the viral mimetic polyinosinic:polycytidylic acid to pregnant rats as a model of MIA, I demonstrated that a maternal antiviral response is associated …

Illuminating Transfer Rna Variants As Genetic Modifiers In Models Of Human Disease, Jeremy T. Lant

Electronic Thesis and Dissertation Repository

Transfer RNAs (tRNAs) physically link the genetic code to an amino acid sequence, by recruiting amino acids to three-nucleotide codons in messenger RNAs. To ensure that the genetic code is translated as intended, tRNAs must be accurately aminoacylated and faithfully recognize codons in the ribosome during protein synthesis. Given the critical function of tRNAs, it has often been assumed that mutations in human tRNA genes would be either lethal to cells or not significantly impair tRNA function. My goal was to rigorously test this assumption in mammalian cell models, prompted by the recent discovery of unprecedented variation in human tRNA …

Connexin 43 Contributes To Phenotypic Variability Of The Mouse Skull, Elizabeth Jewlal

Electronic Thesis and Dissertation Repository

The purpose of this study was to determine whether connexin 43 (Cx43) contributes to craniofacial phenotypic variability. Skull shape and variation were compared within and among two heterozygous mutant mouse models (G60S/+ and I130T/+) that exhibit different levels of Cx43 channel function when compared to their wildtype counterparts (~80% and ~50% reduction in function, respectively). Results indicated mutants have significant differences in skull shape compared to wildtype littermates. Similar patterns of shape difference were found in both mutants. Increased skull shape variation and a disruption in the covariation of skull structures were observed in G60S/+ mutants only. These results show …

Spatiotemporal Characterization Of The Prr12 Paralogues In Zebrafish, Renee Jeannine Resendes

Electronic Thesis and Dissertation Repository

Pathogenic variants in the human PRR12 (Proline Rich 12) gene are associated with PRR12-related Neuroocular Syndrome. However, little is known about the gene/protein function. The zebrafish was utilized to address this, as its attributes place it as a premier model to study genes involved in human development and disease. In situ hybridization and RT-PCR of embryos and larvae, and qRT-PCR of adult tissues revealed the spatial and temporal distributions of the prr12 paralogues: prr12a and prr12b. Both paralogues were detected from the maternal and zygotic transcriptomes in a global and diffuse expression pattern, and there was enrichment …