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Title: Role of the Visual System Homeobox gene 1 (VSX1) in keratoconus and mouse development
Author: Sheppard, Jack
ISNI:       0000 0004 2751 7413
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2008
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available