Life Sciences Commons^™

High Molecular-Weight Hyaluronan Prevents Basal Cell Carcinoma Via Promoting Apoptosis In Cancer-Initiating Adult Stem Cells, Violet Liu

Electronic Thesis and Dissertation Repository

Basal cell carcinoma (BCC), a keratinocyte cancer, is the most common human neoplasm worldwide. Although rarely metastatic, BCC is associated with high morbidity rates with globally rising incidence rates. Accompanying the increase in newly diagnosed cases, the societal cost for BCC treatment in Canada is also expected to inflate, exceeding over $900 million/year by 2031. Chronic UVB exposure has been identified as the primary carcinogen that causes activating mutations in the hedgehog signaling pathway. However, there are no effective preventative methods against BCC, since meta-analyses report sunscreen application does not reduce BCC in compliant patients. The native high molecular-weight hyaluronan …

Investigating The Regulatory Circuitry Of Protein Kinases And Proteases In Apoptosis, Stephanie A. Zukowski

Electronic Thesis and Dissertation Repository

Apoptosis is a tightly regulated cellular process essential for normal development and tissue homeostasis. Perturbations to apoptotic signaling underscores numerous pathogenic processes emphasizing the importance of apoptotic regulation. During apoptosis, caspases orchestrate cellular degradation through proteolytic cleavage of key structural and enzymatic proteins. In a different manner, protein kinases regulate apoptosis by catalyzing the post-translational phosphorylation of substrate proteins to facilitate either pro- or anti-apoptotic signal transduction pathways. Emerging paradigms have indicated that bidirectional crosstalk between protein kinases and caspases serves to globally fine-tune the equilibrium between signals directing cell survival and cell death. In this regard, identifying points of …

The Epigenetic Regulators Atrx And Ctcf Are Required For Mouse Neuroprogenitor Cell Survival And Brain Development, Lauren Ashley Watson

Electronic Thesis and Dissertation Repository

Emerging evidence implicates the regulation of higher-order chromatin structure in brain development, maturation, and function. Human mutations in two important regulators of chromatin structure, ATRX and CTCF, cause microcephaly and intellectual disability and have been identified in several cancers, suggesting an important role for these proteins in the developing brain and to suppress tumorigenesis. This thesis demonstrates that chromatin structure is critical to the differentiation and survival of neural progenitor cells, and explores the mechanisms of ATRX and CTCF function in brain development. The first chapter identifies that Atrx deficiency induces replicative DNA damage at telomeres and pericentromeric heterochromatin, and …

The Role Of The Ku70 Vwa Domain In The Response To Dna Double Strand Breaks, Victoria L. Fell

Electronic Thesis and Dissertation Repository

Ku is an abundant, highly conserved DNA binding protein found in both prokaryotes and eukaryotes that plays essential roles in the maintenance of genome integrity. In eukaryotes, Ku is a heterodimer comprised of two subunits, Ku70 and Ku80, and is best characterized for its central role as the initial DNA end binding factor in the “classical” non-homologous end joining (C-NHEJ) pathway, the main DNA double-strand break (DSB) repair pathway in mammals. At the break, Ku directly and indirectly interacts with several C-NHEJ factors and processing enzymes, serving as the scaffold for the entire DNA repair complex. In this work we …

Elucidating The Signalling Pathway Of Mer Tyrosine Kinase Receptor In Efferocytosis, Ekenedelichukwu Azu

Electronic Thesis and Dissertation Repository

Efferocytosis is the clearance of apoptotic cells and is necessary for homeostasis. Mer Tyrosine Kinase (MerTK) is a crucial efferocytic receptor whose loss is associated with chronic inflammatory diseases and autoimmunity. While previous studies have shown that MerTK mediates efferocytosis through a unique mechanism that requires integrins, MerTK signalling pathway remains unknown. Given this unusual internalization mechanism, I hypothesized that MerTK signals and engages integrins through a novel signalling pathway different from that used by other phagocytic receptors. Therefore, this study aimed to identify the signalling pathways activated by MerTK, utilizing conventional cell biology and pharmacological approaches.

I found that …

Investigating The Interplay Between Protein Kinases And Caspases, Jacob P. Turowec

Electronic Thesis and Dissertation Repository

The balance between cell survival and death is a crucial process in human development and tissue homeostasis, but is also misregulated in disease. In large part, apoptosis is controlled by caspases, a hierarchical series of cysteine aspartic acid proteases that demolish the cell by cleaving key structural and enzymatic proteins, but emerging paradigms have highlighted the ability of kinases to regulate caspase activity. One way in which kinases can control the progression of apoptosis is through phosphorylation of caspase substrates, which acts to prevent caspase cleavage of that target.

In this thesis, we develop new strategies to study this regulatory …

Dissecting The Molecular Role Of Distinct Binding Interfaces On The Retinoblastoma Tumor Suppressor In Growth Control And Tumorigenesis., Matthew J. Cecchini

Electronic Thesis and Dissertation Repository

The retinoblastoma tumor suppressor protein (pRB) functions to maintain proliferative control and act as a barrier to tumorigenesis. pRB is capable of regulating E2F transcription factors to mediate control of proliferation through transcriptional regulation of S-phase target gene expression. In addition, pRB can stabilize the CDK inhibitor p27 through an interaction with two ubiquitin ligase complexes. Further, pRB is capable of forming a unique interaction with E2F1 termed the ‘specific’ interaction that is capable of blocking E2F1 induced apoptosis. These functions of pRB are mediated by distinct binding interfaces and their contributions to the overall functionality of pRB are not …