Contribution of b-catenin controlled, intestinal stem cell-associated homeodomain transcription factors to cancer
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Biomedical Sciences
Abstract
This study aims to identify novel molecular mechanisms by which TCF4 and beta-catenin genes control intestinal stem cells and how changes in the properties of these genes may lead to the development of bowel cancer.
The intestine represents an easily accessible developmental system which provides an attractive route to model biologically important intestinal processes such as; embryogenesis, tumorigenesis and stem cell biology. It also provides a unique opportunity for the direct identification and analysis of factors that contribute to development of both normal and tumour tissue.
The transcription factor, TCF4, has been shown to be critical for intestinal stem cell phenotype but how plasticity and self-renewal is regulated by TCF4 is poorly understood. Therefore, in vivo models of mouse gut-tissue-specific depletion of TCF4 on the APCMin, a mouse model of colon cancer background will be studied.
An in-depth understanding of the mechanisms that control differentiation of distinct cell lineages during normal development and cancer intestinal epithelial stem cells by Wnt/beta-catenin signalling, may lead to identification of novel therapeutic targets.
Given that beta-catenin signalling is deregulated in several different types of cancer, this may also lead to greater understanding of these tumours and of carcinogenesis in general.
The intestine represents an easily accessible developmental system which provides an attractive route to model biologically important intestinal processes such as; embryogenesis, tumorigenesis and stem cell biology. It also provides a unique opportunity for the direct identification and analysis of factors that contribute to development of both normal and tumour tissue.
The transcription factor, TCF4, has been shown to be critical for intestinal stem cell phenotype but how plasticity and self-renewal is regulated by TCF4 is poorly understood. Therefore, in vivo models of mouse gut-tissue-specific depletion of TCF4 on the APCMin, a mouse model of colon cancer background will be studied.
An in-depth understanding of the mechanisms that control differentiation of distinct cell lineages during normal development and cancer intestinal epithelial stem cells by Wnt/beta-catenin signalling, may lead to identification of novel therapeutic targets.
Given that beta-catenin signalling is deregulated in several different types of cancer, this may also lead to greater understanding of these tumours and of carcinogenesis in general.
Technical Summary
While the biological roles of canonical Wnt/b-catenin signalling in development and malignant evolution are well documented, understanding the molecular logic underlying these functionally distinct nuclear transcriptional programs remains a major challenge. Many proteins are associated with cytoplasmic b-catenin for regulation of Wnt/-catenin pathway activities, but the Lef/TCF family of transcription factors remain the sole focus as unambiguous DNA binding partners. However, in addition to Tcf/Lefs, the interaction of b-catenin with several other transcriptional co-regulators may be required for gene expression distinct patterns engage in development versus a malignant evolution.
Hypothesis
Developmentally important homeodomain transcription factors linked to b-catenin, which contribute to intestinal epithelial stem cell maintenance in the context of normal b-catenin status, are de-regulated in the transition to intestinal cancer stem cells.
Goals
1) To define how the vast and constantly varying spectrum of b-catenin protein-modifications is interpreted to produce alterations in cellular-phenotype.
2) To examine the functionally distinct actions of the TCF4 in response to b-catenin during the generation of diverse cell types from pluripotent precursors during development and carcinogenesis.
3) Characterisation any additional transcriptional strategies independent to and/or competitor to the TCF4:b-catenin to achieve the pleiotropic effects of the Wnt/b-catenin-signalling pathway.
Objectives and research plans
1) The yeast Ras recruitment system, already established by the applicant (2) will be carried out to isolate new-cofactors that bind to phosphorylated and/or un-phosphorylated b-catenin (Fig 1A). We speculate that this information could be shared with normal proliferating crypt cells including the IES cells and shared and distinct cofactors will be identified.
2) Stem cells are a pluripotent, self-renewing cell type that give rise to differentiated cells. To the stem cell fate determination in vivo, we intend to develop a novel in vivo model of mouse transgenic line in which the expression of H2B-GFP is controlled by a specific mouse intestinal stem cell marker, Musashi-1 promoter [Pmsi] (5,6) and with the gut-conditional villin-Cre mediated-recombination (Fig 1B).
3) The transcription factor, TCF4, a key feature of IES cells but how pluripotency and self-renewal is co-regulated by both TCF4 and b-Catenin is poorly understood. Therefore, in vivo models of conditional knockout of TCF4 (loss of function) and APCMin a gain of constitutive activation of b-catenin are proposed (Fig 1C).
4) Whether additional transcriptional strategies are required of the Wnt/b-catenin signalling pathway, to both stem cell and cancer cell function, TCF4DG, and APCMin crossed to the; Pmsi-H2B-GFP reporter mouse will be analysed.
Hypothesis
Developmentally important homeodomain transcription factors linked to b-catenin, which contribute to intestinal epithelial stem cell maintenance in the context of normal b-catenin status, are de-regulated in the transition to intestinal cancer stem cells.
Goals
1) To define how the vast and constantly varying spectrum of b-catenin protein-modifications is interpreted to produce alterations in cellular-phenotype.
2) To examine the functionally distinct actions of the TCF4 in response to b-catenin during the generation of diverse cell types from pluripotent precursors during development and carcinogenesis.
3) Characterisation any additional transcriptional strategies independent to and/or competitor to the TCF4:b-catenin to achieve the pleiotropic effects of the Wnt/b-catenin-signalling pathway.
Objectives and research plans
1) The yeast Ras recruitment system, already established by the applicant (2) will be carried out to isolate new-cofactors that bind to phosphorylated and/or un-phosphorylated b-catenin (Fig 1A). We speculate that this information could be shared with normal proliferating crypt cells including the IES cells and shared and distinct cofactors will be identified.
2) Stem cells are a pluripotent, self-renewing cell type that give rise to differentiated cells. To the stem cell fate determination in vivo, we intend to develop a novel in vivo model of mouse transgenic line in which the expression of H2B-GFP is controlled by a specific mouse intestinal stem cell marker, Musashi-1 promoter [Pmsi] (5,6) and with the gut-conditional villin-Cre mediated-recombination (Fig 1B).
3) The transcription factor, TCF4, a key feature of IES cells but how pluripotency and self-renewal is co-regulated by both TCF4 and b-Catenin is poorly understood. Therefore, in vivo models of conditional knockout of TCF4 (loss of function) and APCMin a gain of constitutive activation of b-catenin are proposed (Fig 1C).
4) Whether additional transcriptional strategies are required of the Wnt/b-catenin signalling pathway, to both stem cell and cancer cell function, TCF4DG, and APCMin crossed to the; Pmsi-H2B-GFP reporter mouse will be analysed.
