Cardiac development is a complex multi-step process involving a diverse network of genes. Defects in cardiac genes can lead to congenital heart defects (CHDs), and understanding the processes involved in normal cardiogenesis is crucial in elucidating the pathogenesis of disease. Mutations in a number of cardiac transcription factors have been associated with CHDs, including TBX5 and GATA-4. These transcription factors are high in the regulatory hierarchy and form a complex that is thought to direct and synergistically regulate common cardiac pathways. However, little is currently known about their joint targets. This study aimed to identify and analyse genes important in cardiogenesis, with focus on the combined targets of TBX5 and GAT A-4. Microarray expression analysis of TBX5/ GATA-4 double overexpression P19 cell lines led to the identification of a large number of genes, of which seven were selected for study; PA2.26, PETA-3, FUCA 1, FN, TPM1, DES, and RBMS1. Expression of these was confirmed in the embryonic chick heart at Hamburger and Hamilton (HH) stages 12 - 26. The cell cycle regulator and transcription factor RBMS1 was selected for investigation of its role in cardiac development. Morpholino knockdown of RBMS1 expression in the developing chick resulted in defects in cardiac looping and atrial septation. Whilst further work is required to strengthen this data, this is a novel finding and opens up possibilities for future research into cardiac transcriptional networks. Microarray expression analysis using an in ovo model of TBX5 and GATA-4 double knockdown led to the identification of a number of interesting putative targets, including TFAP2B, GPC3, and CRABP1, which have known roles in cardiac development. TFAP2B is of particular interest as mutations in this gene are associated with the heart-hand disorder Char syndrome. LOC420770, a novel gene of unknown function, was also identified and displayed expression indicative of a heart-limb profile. Further studies to attempt elucidation of the function of this gene may provide a novel candidate gene for CHD. Investigation of these genes will form the basis of future research, contributing to our current knowledge of the vast network of genes involved in development of the heart.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:555426 |
| Date | January 2011 |
| Creators | Patel, Bhakti R. |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/28066/ |
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