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Title: Cellular functions of Msx1 and Msx2
Author: Oram, Cecilia Mercedes
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2001
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Previous work showed that ectopic expression of Msx2 in primary cultures of pigmented retinal epithelium (PRE) cells promotes a small proportion of transfected cells to develop a neural-like phenotype and to downregulate expression of key pigmentation transcription factor, MITF. In the experimental work described in this thesis I show that ectopic expression of Msx2 in dedifferentiated chick PRE cells promotes the formation of cells with a neural-like phenotype. Using dedifferentiated PRE cells substantially increasing the number of the small number of neural-like cells in the Msx2-transfected PRE cultures is independent of serum growth factors. However, the proportion of Msx2-transfected cells developing a neural-like phenotype is not markedly increased by neural-specific culture conditions. I have found no evidence of an increase in PRE cell proliferation as a result of ectopic Msx2 expression. Interestingly, ectopic expression of Msx1 in PRE cells also promotes the development of a neural-like phenotype in a small number cells and results in downregulation of MITF. This suggests that, at least in these cellular functions, Msx1 and Msx2 are functionally redundant. To test the in vivo relevance of the in vitro cellular assay, I analyzed transgenic mice designed to express Msx2 ectopically in the PRE with bGal and neomycin produced from an internal ribsome entry site (IRES). Mice in one transgenic line showed patches of bGal reporter gene in the PRE suggesting activity of the Msx2 transgene in some cells. However, no ectopic Msx2 expression could be detected by in situ hybridization. Transgenic mice were produced without the IRES bGeo cassette to investigate whether this was negatively affecting Msx2 transgene activity. Mice from stable transgenic lines and transient transgenic embryos did not show ectopic Msx2 expression when assayed by in situ hybridization. The in vitro system provides an assay for the cellular and development functions of the MSX proteins and points to a development context where could be investigated in vivo.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available