Role of the Visual System Homeobox gene 1 (VSX1) in keratoconus and mouse development

Sheppard, Jack 2008. Role of the Visual System Homeobox gene 1 (VSX1) in keratoconus and mouse development. PhD Thesis, Cardiff University.

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Abstract

The main aims of this thesis were to examine the role of the Visual System Homeobox gene 1 (VSX1) in keratoconus and development using molecular biology techniques and biophysics. The opportunity existed to examine a Vsxl knockout mouse using X-ray diffraction to see whether the structure of the cornea was altered due to the removal of this gene. Upon examination with X-ray diffraction further experiments were devised in order to clarify possible interactions of other genes that may play a part in keratoconus pathogenesis. The interfibrillar and intermolecular collagen spacings and the average collagen fibril diameters between Vsxl knockout mice and background matched littermate controls were compared. There were no statistical differences found in all cases. This is a similar finding to human keratoconic corneas when compared with normal controls. It was found that the Vsxl knockout mouse had significant alterations to the preferential alignment of collagen fibrils and altered corneal collagen mass distribution. This also is similar to human keratoconic corneas, strengthening the proposition that the Vsxl knockout mouse is a model system for keratoconus. Additionally, significantly altered expression levels of the genes HSF1, Hsp47 and Aqp5 were found along with no expression of Col8a2. It was believed that the initial fault that allows keratoconus to develop occurs during development, so to explore this normal mouse development was explored using X-ray diffraction to map the collagen fibrils of the cornea as it develops in postnatal stages. This would provide a good baseline for future experiments. In addition to this, initial investigation of the expression of the Vsxl gene was undertaken to see whether it may play a role in development. It was found that the annulus of collagen fibrils that plays an important role in maintaining the structure of the cornea starts to develop at postnatal day 10 in the mouse and continues until maturity. It was also found that there is a significant alteration in expression of Vsxl which occurs in development between postnatal day 5 and day 12. Lastly a population of keratoconus patients in South Wales were screened for mutations in the Vsxl gene. Mutations in Vsxl have been observed in other studies and this investigation was undertaken in order to clarify the ongoing debate into mutations in Vsxl and their link to keratoconus. In the study presented here a number of previously identified polymorphisms were discovered in out cohort of patients but no polymorphism was deemed to be a disease causing mutation.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Optometry and Vision Sciences
Subjects:	R Medicine > RE Ophthalmology
ISBN:	9781303214097
Funders:	MRC
Date of First Compliant Deposit:	30 March 2016
Last Modified:	12 Feb 2016 23:13
URI:	https://orca.cardiff.ac.uk/id/eprint/54796

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