Drosophila as a Model to Understand Second Heart Field Development

Abstract

The genetic model system Drosophila has contributed fundamentally to our understanding of mammalian heart specification, development, and congenital heart disease. The relatively simple Drosophila heart is a linear muscular tube that is specified and develops in the embryo and persists throughout the life of the animal. It functions at all stages to circulate hemolymph within the open circulatory system of the body. During Drosophila metamorphosis, the cardiac tube is remodeled, and a new layer of muscle fibers spreads over the ventral surface of the heart to form the ventral longitudinal muscles. The formation of these fibers depends critically upon genes known to be necessary for mammalian second heart field (SHF) formation. Here, we review the prior contributions of the Drosophila system to the understanding of heart development and disease, discuss the importance of the SHF to mammalian heart development and disease, and then discuss how the ventral longitudinal adult cardiac muscles can serve as a novel model for understanding SHF development and disease.

Keywords: DiGeorge syndrome; Drosophila; development; heart; second heart field.

Figure 1

Organization of the Drosophila heart during development. Left: Diagrams of heart structure; right: images of the heart from different stages of development. Anterior is to the left. (A): The wild-type (WT) embryonic and larval structure comprises a posterior heart and an anterior aorta supported by alary muscles. (B): At the adult stage, the larval aorta has been remodeled into a robust heart tube perforated by ostia. Heart of a knockdown lacking ventral longitudinal muscles is shown to visualize the heart tube. (C): Wild-type adult heart showing ventral longitudinal muscles. Adult photomicrographs show the heart only and not the aorta.