Role of the T-box transcription factors, Tbx5 and Tbx20, in cardiac development and congenital heart disease

Funded Activity Summary

Structural defects in the heart are present in approximately 1 in 100 live births, and 1 in 10 still births in developed countries. Some 8% of deaths in the first year of life are caused by such abnormalities. While some defects can be repaired in childhood many go undetected and compound in later years leading to sudden death or compromised quality of life. Virtually all inherited heart defects for which the underlying genetic alteration is known are caused by mutations in genes controlling development of the heart in the embryo. Examples are Tbx5, a member of the T-box family of transcription factor genes mutated in Holt Oram syndrome, and Nkx2-5, a homeodomain transcription factor gene mutated in families with hole in the heart and cardiac electrical defects. We propose to investigate the involvement of a new member of the T-box gene family, Tbx20, in cardiac development and disease, and to compare and contrast its function with that of Tbx5. The Tbx5 and Tbx20 proteins interact directly with Nkx2-5 to stimulate transcription of cardiac genes, making Tbx20 a good candidate for involvement in inherited disease. We will use gene targeting technology to delete the Tbx20 gene in mice, and will analyse heart anatomy, gene expression and function to determine the effect of its loss. We will also investigate how Tbx20 interacts with other cardiac regulatory pathways, by crossing Tbx20 mutant mice with mice deficient for Nkx2-5 and Tbx5, strains that show heart abnormalities similar to those found in human patients. Microarray technology, which examines gene expression on a whole genome scale, will also be used to identify genes that are regulated by these transcription factors. Finally, we will search for mutations in the Tbx20 gene in human patients that have inherited heart abnormalities. In doing so we may improve our understanding of disease causation and predisposition thereby identifying patients at risk and providing improved genetic counselling and diagnosis.

Funded Activity Details

Start Date: 01-01-2003

End Date: 01-01-2004

Funding Scheme: NHMRC Project Grants

Funding Amount: $345,000.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Genetic Development (Incl. Sex Determination)

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

cardiac malformation | congenital heart disease | developmental genes | embryology | embryonic development | heart | knockout mice | organogenesis

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