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Directed Differentiation Of Human Embryonic Stem Cells To Pancreatic Endocrine Progenitors, Nicole Marie Watts

Digitized Theses

Diabetes is becoming increasingly prevalent in North America, highlighting the necessity to create a renewable source of pancreatic P-cells for therapeutic purposes. The current study was undertaken to explore the hypothesis that ectopic expression of lineage­ determining transcription factors could generate a source of proliferative, homogenous pancreatic progenitor cells capable of subsequent differentiation to functional endocrine cell types, including P-cells. We validated transgenic systems for transgene delivery in HESC and subsequently generated and analyzed gene expression patterns in transgenic cell populations engineered to constitutively express pancreatic transcription factors PAX4, PDX1, or NGN3. We demonstrate that ectopic expression of either PAX4 …

The Effect Of Connexin43 On The Development Of Skeletal Muscle Using Cell And Animal Models Of Oculodentodigital Dysplasia, Pasquale Vecchio

Digitized Theses

Skeletal muscle development involves the differentiation of myoblasts into myotubes; likely involving connexins (Cx) and the gap junctional exchange of secondary messengers and metabolites. Many patients with oculodentodigital dysplasia (ODDD), a rare primarily autosomal dominant disease caused by mutations in the gene encoding Cx43, become less ambulatory with aging and exhibit symptoms that may reflect defects in skeletal muscle development, maintenance, and repair. In this study, the role of Cx43 in skeletal muscle development was examined in differentiation-competent L6 myoblasts and two ODDD- linked Cx43-mutant mouse lines. Undifferentiated L6 myoblasts exhibited high levels of Cx43-based gap junctions which were inhibited …

Reactive Oxygen Species Signaling In Extraembryonic Endoderm Differentiation, Jason W.H. Wen

Digitized Theses

Development of extraembryonic endoderm is essential for proper placenta formation and mammalian embryogenesis. Formation of primitive endoderm from cells of the inner cell mass is one of the earliest cell fate decisions made in the developing embryo. However, the signals and mechanisms involved in orchestrating this developmental process are not completely understood and are difficult to study in vivo. The mouse embryonic carcinoma (F9) cell line can be chemically re-programmed to mimic cells of the inner cell mass, thereby serving as an in vitro model to study extraembryonic endoderm differentiation. F9 cells treated with retinoic acid (RA) differentiate into primitive …

The Skeletal Phenotype Of Roralpha-Deficient Mice, Chantai I. Tacchino

Digitized Theses

Bones grow longitudinally through the process of endochodral bone formation. The size of bones is regulated by chondrocyte proliferation, differentiation and remodelling. Retinoic acid receptor-related orphan receptor alpha, RORα, is a nuclear receptor involved in differentiation of many tissues and was recently identified as a putative regulator of chondrocyte differentiation. The goal of this thesis was to analyse the in-vivo role of RORα in chondrocyte differentiation. The in vivo model of Rora deficiency, staggerer mouse, and controls were employed for this analysis. Skeletal morphology, length and ossification were analysed by skeletal preparations. Histological analysis of cartilage and remodelling markers was …

Connexin36 Is A Negative Regulator Of Differentiation In Human Neuroblastoma Cells, Mandeep Sidhu

Digitized Theses

Gap junction channels permit intercellular communication through the passage of small molecules and metabolites between adjacent cells and are involved in regulating cellular processes such as homeostasis, differentiation, and proliferation. Connexins (Cx) are the constituent proteins of gap junctions and the neuronal connexin, Cx36, is highly expressed in the developing nervous system. In the present study, the effect of Cx36 on differentiation was investigated by manipulating Cx36 expression levels and inducing differentiation of SH-SY5Y cells. Following retinoic acid induced differentiation of SH- SY5Y cells, Cx36 mRNA expression increased, while Cx45 mRNA expression was unaffected. Cx36 overexpression resulted in diminished retinoic …

Gata6 Induces Wnt6 Expression During Primitive Endoderm Differentiation, Jason T.K. Hwang

Digitized Theses

Mouse F9 teratocarcinoma cells in culture differentiate into primitive endoderm when treated with retinoic acid and into parietal endoderm with subsequent treatment with dibutyryl cAMP. This in vitro model has been studied extensively as these chemically induced events mimic one of the earliest epithelial-to-mesenchymal transitions in mouse embryogenesis. During differentiation to primitive endoderm Wnt6 expression is up- regulated by RA, and the result is the activation ofthe canonical Wnt/p-catenin signaling pathway. Thefactor(s)responsiblefortheactivationoftheWnt6geneisnotknown,but in silico analysis reveals that its promoter region contains a putative binding site for the transcription factor GATA6. In this study, the expression of Gata6 following retinoic acid …

Involvement Of Fzd7 Signaling In Extraembryonic Endoderm Differentiation, Ben H. Cadesky

Digitized Theses

The mouse F9 teratocarcinoma cell line is used to mimic primitive endoderm differentiation and the subsequent parietal endoderm differentiation seen in vivo during early mouse development. This is achieved by treating undifferentiated F9 cells with the morphogen retinoic acid (RA) to form primitive endoderm and with RA and dibutyryl cyclic AMP to form parietal endoderm. The in vitro F9 model has been studied extensively because the differentiation from primitive to parietal endoderm is one of the earliest epithelial-to-mesenchymal transitions seen in mouse development. RA has been shown to upregulate Wnt6 in F9 cells, which signals through the canonical (3-catenin pathway. …

Implications Of Pannexin 1 And Pannexin 3 In Keratinocyte Differentiation, Steven J. Celetti

Digitized Theses

Pannexin (Panx) 1 and Panx3 are integral membrane proteins with sequence homology to the invertebrate gap junctions, innexins, and are expressed in mammalian skin. Panxs form functional single-membrane channels but their importance in regulating cellular function is poorly understood. In this study, the expression of Panx 1 and Panx3 was assessed in mouse skin and the role of these Panxs in kératinocyte differentiation was

investigated using differentiation-competent rat epidermal kératinocytes (REKs) engineered to over-express Panxl, Panxl-GFP or Panx3. Endogenous levels of a unique 70 kDa species of Panx3 increased in organotypic epidermis, while Panxl remained

unchanged compared to monolayer REKs. …

Gata6 Induces Wnt6 Expression During Primitive Endoderm Differentiation, Jason T.K. Hwang

Digitized Theses

Mouse F9 teratocarcinoma cells in culture differentiate into primitive endoderm when treated with retinoic acid and into parietal endoderm with subsequent treatment with dibutyryl cAMP. This in vitro model has been studied extensively as these chemically induced events mimic one o f the earliest epithelial-to-mesenchymal transitions in mouse embryogenesis. During differentiation to primitive endoderm Wnt6 expression is up- regulated by RA, and the result is the activation o f the canonical W nt/p-catenin signaling pathway. The factor(s) responsible for the activation o f the Wnt6 gene is not known, but in silico analysis reveals that its promoter region contains a …

Differential Effects Of Igf-I And Igf-Ii On The Fate Of Mouse Trophoblast Stem Cells, Robert Stanley Porteous

Digitized Theses

The main objective of this thesis was to identify the role(s) of IGF-I and IGF-II on the fate of mouse trophoblast stem cells (TS cells) and their role in contributing to the stem cell fate, when grown in the absence of additional growth factors. By analyzing the expression of self-renewal and trophoblast-specific transcription factors, the addition of IGF-I and IGF-II restored nuclear OCT4 and CDX2 expression, with IGF- II inducing a longer effect, while the expression of SOX2 was not restored. IGF-I was found to induce the differentiation of TS cells based on expression and quantitative analysis of PL-1 expression. …