Investigating the role of Wnt/β-catenin pathway in pluripotency and somatic cell reprogramming
The adaptive response of cells to external stimuli is an intriguing mechanism at the basis of the existence of life itself. For this purpose, signalling pathways and gene regulatory networks elegantly evolved translating extracellular signals into finely tuned cellular responses. Among them, the Wnt...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/552942 |
| Acceso en línea: | http://hdl.handle.net/10803/552942 |
| Access Level: | acceso abierto |
| Palabra clave: | Wnt/ß-catenin Pluripotency Reprogramming ß-catenin TCF1 Pluripotencia Reprogramación 576 |
| Sumario: | The adaptive response of cells to external stimuli is an intriguing mechanism at the basis of the existence of life itself. For this purpose, signalling pathways and gene regulatory networks elegantly evolved translating extracellular signals into finely tuned cellular responses. Among them, the Wnt/ß-catenin signalling pathway converges on the regulation of ß-catenin protein, which, in turn regulates target gene expression. In particular the Wnt/ß-catenin pathway plays a pivotal role in sustaining pluripotency and somatic cell reprogramming. Here we identified a temporal of Wnt/ß-catenin activity during somatic cell reprogramming, controlling the expression levels of mesenchymal-to-epithelial transition and senescence-associated genes through TCF1. We demonstrated that the “Wnt-OFF” state is an early reprogramming marker and that dynamic modulation can be effectively used to increase the reprogramming efficiency. Furthermore the Wnt/ß-catenin pathway is a key regulator of pluripotency and self-renewal of mouse embryonic stem cells (mESCs) and a small-molecule activator of the Wnt pathway is widely used to maintain embryonic stem cells in a ground state of pluripotency. The role of ß-catenin in mESCs is however still controversial. We noticed available ß-catenin knock-out models are flawed by the production of N-terminally truncated proteins with unknown functions. We therefore generated a novel ß-catenin knock-out using CRISPR/Cas9 technology, hoping to have clearer insight of ß-catenin functions in mESCs. We have also found that ground state pluripotency promoted by sustained Wnt pathway activation cannot be maintained indefinitely, resulting in a “lapsed” ground state possibly due, among other factors, to regulatory negative feedback loops that impair Wnt/ß-catenin activity. |
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