Genetic and Molecular Dissection of Laterality in the Developing Heart

Funded Activity Summary

Vertebrate animals display an external bilateral symmetry. However, most internal organs are located asymmetrically and show profound left-right structural asymmetries during development. For each species, these laterality characteristics are constant. Inherited laterality disorders occur in humans and, although rare, are associated with high mortality rates due to discordant cardiovascular development. Moreover, subtle anomalies of laterality may underlie a host of congenital heart abnormalities. In early embryogenesis, the newly-formed heart tube loops to the right, an event which establishes the correct alignment of the future cardiac chambers. The direction of heart looping is determined by genetic pathways that establish laterality in the early embryo. A component of this pathway is a TGFbeta-family signalling molecule, nodal, which is activated on the left side of the forming heart and other organs. Nodal then activates the transcription factor gene Pitx2. The aim of this project is to examine the consequences of genetic inactivation of the mouse nodal and Pitx2 genes in the heart, and to discover cardiac genes downstream of these genes. We will specifically test the hypothesis that laterality contributes to heart chamber formation in addition to setting the direction of looping. Ablation of these genes in the whole embryo leads to complex defects that preclude analysis of their functions in the heart. To achieve heart-specific deletion, we will use a conditional gene ablation technology that exploits the bacteriophage recombinase, Cre. Genes downstream of Pitx2 and Nodal will be discovered using microarray technology, which allows us to screen exhaustively for changes in gene expression between different tissues. This project will help us solve the complex genetic basis of congenital cardiac abnormalities in humans, and will contribute to our understanding of how heart chambers form, potentially useful in stem cell-based therapies for the failing heart.

Funded Activity Details

Start Date: 01-01-2002

End Date: 01-01-2004

Funding Scheme: NHMRC Project Grants

Funding Amount: $379,370.00

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

Congenital heart disease | Heart | Heterotaxia | Isomerism | Kartagener's syndrome | Laterality | Morphogenesis | Mouse genetics | Patterning | Rieger's syndrome

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