Biochemistry Commons^™

Selective Activation Of Thrombin Activatable Fibrinolysis Inhibitor (Tafi) Attenuates Metastatic And Angiogenic Capabilities Of Melanoma And Lung Carcinoma In Vitro, Jacklyn Krizsan

Electronic Thesis and Dissertation Repository

Metastasis and angiogenesis are hallmarks of aggressive cancers, both depending on degradation of extracellular matrix by proteases such as plasmin. Plasmin activation is inhibited by thrombin-activatable fibrinolysis inhibitor (TAFI)-mediated cleavage of terminal lysine residues on plasminogen receptors. Activation of TAFI is most effectively done in complex with thrombomodulin (TM). TM is known to have anti-cancer properties, but it is not known if this is due to TAFI activation or an alternative substrate protein C (PC). We hypothesize that specific promotion of TAFI activation with TM treatment will attenuate metastatic and angiogenic capabilities of tumour cells.

Melanoma and lung carcinoma cells …

Elucidating The Biomechanics Of Mertk-Mediated Efferocytosis, Brandon Hayato Dickson

Electronic Thesis and Dissertation Repository

Macrophages are key mediators of efferocytosis – the phagocytic engulfment and removal of apoptotic cells. During engulfment, the coordinated activity of efferocytic receptors induces the remodeling of the actin cytoskeleton, which facilitates the envelopment of the cell by the plasma membrane. Mer receptor tyrosine kinase (MERTK) is a crucial efferocytic receptor, but its role during actin remodeling is not well understood. Previously, our lab showed that MERTK is an activator of β₂ integrins – which are comprised of receptors known to induce the actin polymerization that is required for engulfment. We hypothesized that MERTK is an indirect stimulator of …

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 …

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 …

The Regulation Of Pannexin1 And Pannexin2 In The Skin In Health And Disease, Rafael E. Sanchez Pupo

Electronic Thesis and Dissertation Repository

Pannexins (PANX1, 2, 3) are a family of channel-forming glycoproteins that mediate intracellular and paracrine signaling. In contrast to PANX2, PANX1 has been extensively investigated in the skin, modulating cell differentiation, wound healing, and melanoma development. PANX1 and PANX2 can co-exist in the same cell and form mixed channels where their glycosylation seems to regulate their intermixing. N-glycosylation and caspase cleavage have been proposed as modulators of the function of PANX1, but their effects on PANX2 are unknown. We explored the PANX2 expression in mouse skin and showed that a Panx2 splice variant (PANX2-202) is continuously expressed throughout aging skin. …

Characterization And Modulatory Influence Of Pyruvate Kinase Muscle Isoforms 1 And 2 Within The Murine Pluripotent Continuum, Joshua G. Dierolf

Electronic Thesis and Dissertation Repository

Mouse embryonic stem cells (mESCs) and mouse epiblast stem cells (mEpiSCs) represent opposite ends of a pluripotency continuum, respectively referred to as naïve and primed pluripotent states. A third, recently discovered intermediate state has been described as the ‘formative state’. Metabolism has been traditionally regarded as a by-product of cell fate; however, recent evidence now supports metabolism as promoting stem cell fate. Pyruvate kinase muscle isoforms 1 and 2 (PKM1 and PKM2) catalyze the final, rate limiting step of glycolysis generating adenosine triphosphate (ATP) and pyruvate; however, the precise role(s) of these isozymes in naïve, formative, and primed pluripotency is …

Dnajc7, A Molecular Chaperone Protein That Modulates Protein Misfolding In Amyotrophic Lateral Sclerosis (Als), Meaghan Kathleen Stoltz

Electronic Thesis and Dissertation Repository

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease associated with protein misfolding and dysregulated cellular protein quality control mechanisms. Molecular chaperones, and heat shock proteins (Hsp), are key players in maintaining cellular protein quality control. DNAJC7 is an understudied cytosolic Hsp40 that works together with Hsp70 and Hsp90 to regulate proper protein folding or degradation. Of note, mutations in the gene encoding DNAJC7 were discovered to cause familial ALS. We asked whether ALS-associated mutations in DNAJC7 compromise its function as a chaperone, which may cause the toxic accumulation of misfolded proteins. This study attempts to uncover the functions of DNAJC7 …

Thyroxine-Dependent And -Independent Effects On Premature Aging And Myelination In Atrx Mutant Mice, Megan E. Rowland

Electronic Thesis and Dissertation Repository

ATRX is an ATP-dependent chromatin remodeler required to safeguard genomic integrity. Conditional deletion of Atrx in the mouse embryonic forebrain and anterior pituitary in Atrx^Foxg1Cre mice phenocopies mouse models of progeria which display increased DNA damage, coupled with reduced lifespan, growth and subcutaneous fat. These mice also have severely low circulating levels of insulin like growth factor 1 (IGF-1) and (T4) which have been reported in models of premature aging. Based on evidence that Igf1 is activated by the ligand-bound thyroid hormone receptor, I tested whether T4 supplementation could restore IGF-1 levels and ameliorate premature aging phenotypes in Atrx …

Characterizing The Role Of Thymine Dna Glycosylase In Transcriptional Regulation And Cancer In Vivo, Mohammad Haider Hassan

Electronic Thesis and Dissertation Repository

Cytosine methylation (5mC) is essential for transcriptional control and genomic stability and is often used as a prognostic marker in cancer. Although 5mC has long been considered a relatively stable epigenetic mark, recent studies have demonstrated that it can be reversed enzymatically by TET proteins which oxidize 5mC into 5-hydroxymethylcytosine (5-hmC), and then to 5-formylcytosine (5-fC) and 5-carboxylcytosine (5caC). This mechanism is known as active DNA demethylation and the base excision repair enzyme Thymine DNA Glycosylase (TDG) plays an essential role in this process by removing 5-fC and 5-caC which are subsequently replaced by the unmethylated cytosine. Importantly, homozygous loss …

Regulation Of C-Raf Stability By The Ranbpm/Ctlh Complex, Christina J. Mctavish

Electronic Thesis and Dissertation Repository

RanBPM is an evolutionarily conserved multi-domain protein that has been implicated in the regulation of several cellular process, including protein stability, cell migration, gene transcription, and apoptosis. RanBPM is identified as a key member of the CTLH complex, an orthologous complex to a yeast E3 ubiquitin ligase complex, the exact function of which remains unknown. Previously, our laboratory identified RanBPM as an inhibitor of the ERK1/2 pathway through the modulation of C-RAF protein levels. This study shows that RanBPM-mediated degradation of C-RAF occurs through the proteasome and the entire CRA domain of RanBPM is necessary for direct interaction with C-RAF …

Characterization Of Numb As A Regulator Of Anaplastic Lymphoma Kinase, Ran Wei

Electronic Thesis and Dissertation Repository

Cellular events rely on protein-protein interactions that are often mediated by modular domains which recognize particular sequence motifs in binding partners. The NUMB protein is the first described cell fate determinant and multifaceted adaptor that is involved in a wide variety of cellular events. NUMB mainly mediates protein interactions via its modular PTB domain. Here we present a systematic investigation of the NUMB-PTB interactome by employing an integrative strategy combining both protein and peptide arrays. We profiled NUMB-PTB binding specificity and interacting proteins genome-wide. The receptor tyrosine kinases (RTKs) are found highly enriched in the interactome, raising the possibility that …

The Role Of Bone Sialoprotein In Periodontal Tissue Development And Bone Repair, Yohannes Soenjaya

Electronic Thesis and Dissertation Repository

Bone development and repair involve complex processes that include interaction between cells and their surrounding matrix. In the body, bone sialoprotein (BSP) expression is up-regulated at the onset of mineralization. BSP is a multifunctional acidic phosphoprotein with collagen-binding, hydroxyapatite nucleating, and integrin recognition (RGD sequence, which is important for cell-attachment and signaling) regions. Mice lacking BSP expression (Bsp^-/-), exhibit a bone phenotype with reductions in bone mineral density, bone length, osteoclast activation, and impaired bone healing. This thesis examined the role of BSP in tooth development and also its potential use as a therapeutic reagent for bone …

Analyzing A-Series Gangliosides In Neurons Following Exposure To Glutamate, Dae Hee Park

Electronic Thesis and Dissertation Repository

Neurons within different brain regions have varying levels of vulnerability to external stress and therefore respond differently to injury. A potential reason to explain this may lie within a key lipid class of the cell’s plasma membrane called gangliosides. These glycosphingolipid species have been shown to play various roles in the maintenance of neuronal viability. The purpose of this study is to use electrospray ionization mass spectrometry (ESI-MS) technique and immunohistochemistry to evaluate the temporal changes in the expression profiles of various ganglioside species during the course of neurodegeneration in rat primary cortical neurons exposed to glutamate toxicity. Primary embryonic …

Translesion Synthesis And Mutations: On The Mutagenic Properties Of The Two Dna Lesions, 8-Oxo-G And Pt-Gg, And The Functions Of Y-Family Dna Polymerases And Rev3l On The Bypass Of Each Of The Dna Lesions In Mammalian Cells, Lizhen Guo

Electronic Thesis and Dissertation Repository

I studied the capabilities of the two DNA lesions 8-oxo-guanine and cisplatin intrastrand crosslinked 1,2-d(GpG) or Pt-GG to cause mutations in mammalian cells. Using isogenic cell lines generated from mice with selective gene knockouts of distinct DNA polymerases as models, I deduced the biological functions of the translesion DNA polymerases Pol eta, Pol kappa, Pol iota, Rev1 and Rev3L on bypassing each of the lesions 8-oxo-G and Pt-GG. My study takes advantage of the Next Generation Sequencing (NGS) technology to determine mutagenic effects of the DNA lesions in vivo and effects of translesion DNA polymerases on bypassing the lesions. Through …

Maternal Control Of Genomic Imprinting: Effects Of Infertility And Ovarian Stimulation In A Mouse Model, Michelle M. Denomme

Electronic Thesis and Dissertation Repository

Gametogenesis and early embryogenesis are important stages in which genome-wide epigenetic transitions required for early mammalian development are orchestrated. This is exemplified by the occurrence of genomic imprinting, where epigenetic mechanisms lead to the monoallelic expression of a subset of genes. Parental-specific DNA methylation in the gametes results in the distinct nonequivalence of the parental genomes in the early embryo. Changes from normal gamete and embryo development by impaired fertility or assisted reproductive technologies (ARTs) may disrupt the processes of imprint acquisition and imprint maintenance. My hypothesis is that aberrant imprinted methylation arises from impaired maternal fertility or ovarian stimulation …

Characterizing The Role Of The Retinoblastoma Protein Lxcxe Binding Cleft In Cellular Senescence And Tumor Suppression, Srikanth Talluri

Electronic Thesis and Dissertation Repository

The Retinoblastoma protein (pRB) is a key regulator of the cell cycle and is functionally inactivated in most cancers. pRB has been proposed to utilize simultaneous interactions with E2F transcription factors and chromatin regulatory proteins to repress transcription and block cell cycle progression. The goal of this study is to characterize the physiological role of pRB interactions with chromatin regulatory proteins. I used gene targeted mice carrying point mutations in the murine Rb1 gene (Rb1^∆L) that specifically disrupt pRB’s LXCXE binding cleft, and thereby its ability to interact with chromatin regulatory proteins while leaving its ability to …

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 …

Characterization Of A Tumour Suppressor Function Of Ranbpm, Elnaz Atabakhsh

Electronic Thesis and Dissertation Repository

Ran-binding protein M (RanBPM) is an evolutionarily conserved nucleocytosolic protein that has been proposed to regulate various cellular processes, including protein stability, gene expression, receptor-mediated signalling pathways, cell adhesion, development, and apoptosis. Despite the multitude of functions attributed to RanBPM however, little is known regarding the precise mechanisms by which RanBPM executes these cellular roles. In this work, we seek to address this matter by describing functions for RanBPM in the regulation of apoptotic and pro-survival signalling pathways, and in cellular transformation.

We first identify RanBPM as a pro-apoptotic protein that regulates the activation of the intrinsic apoptotic signalling pathway …

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 …