Renal dysplasia is a disease characterized by developmental abnormalities of the kidney that affect 1 in 250 live births. Depending on the severity of the renal abnormalities, this disorder can lead to childhood kidney failure, adult onset chronic kidney disease, and hypertension. Currently, the best treatment options for patients with renal dysplasia are renal dialysis and kidney transplant. Our limited understanding of the pathogenesis of renal dysplasia has prevented the development of better treatment strategies for those patients. A hallmark of renal dysplasia is an expansion of loosely packed fibroblast cells, termed renal stroma. Markedly elevated levels of β-catenin have been reported in the expanded stromal population in patients with dysplastic kidneys. Yet, the contribution of stromal β-catenin to the pathogenesis of renal dysplasia is not known. Additionally, the role of stromal β-catenin in the developing kidney is not clear. The overall hypothesis of this PhD thesis is that β-catenin in stromal cells controls key signalling molecules that regulate proper kidney development. Furthermore, we hypothesize that elevated levels of β-catenin contribute to the pathogenesis of renal dysplasia. To mimic the human condition, we generated a mouse model that overexpresses β-catenin specifically in the stroma (termed β-catGOF-S). In addition, to gain a better understanding of its role in kidney development, we generated a second mouse model deficient for β-catenin exclusively in stromal cells (termed β-catS-/-). The goal of this study is to utilize these models to understand the role of stromal β-catenin in kidney formation and investigate its contribution to renal dysplasia. The first objective defines the contribution of stromal β-catenin to the genesis of renal dysplasia. We provide evidence for a mechanism whereby the overexpression of stromal β-catenin disrupts proper differentiation of stromal progenitors and leads to an expansion of stroma-like fibroblast cells and vascular morphogenesis defects. In the second objective, we establish a mechanism where stromal β-catenin modulates Wnt9b signaling in epithelial cells to control proliferation of the nephron progenitors. In the third objective, we define a role for stromal β-catenin in proper formation and survival of the medullary stroma. Finally, in a technical report, we outline a protocol to isolate stromal cells in the developing kidney and provide potential downstream applications to further our understanding of stromal β-catenin in the developing kidney.
Taken together, our findings establish a crucial role for stromal β-catenin in the genesis of renal dysplasia and demonstrate, using two mouse models, that stromal β- catenin must be tightly regulated for proper formation of the stroma lineages and development of the kidney. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20409 |
| Date | January 2016 |
| Creators | Boivin-Laframboise, Felix |
| Contributors | Bridgewater, Darren, Medical Sciences (Growth and Development) |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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