The human fly? It might not be as farfetched as one might think—at least in terms of vertebrate heart development that includes humans. University of New Mexico Professor Richard Cripps recently received a $1.375 million grant from the National Institutes of Health to study the connection between the heart of fruit flies, or Drosophila, and how certain genetic heart ailments in humans form.
Photo: Embryo heart of a fruit fly (magnified ~ 600x) stained in brown to outline the muscle cells. The heart is the tubular structure running from right to left across the middle.
“There are similar genes in different animals essentially performing the same function,” said Cripps. “Researchers believe the same biological methods that are used to form the fly heart also form the human heart. Scientists have identified genes performing functions in Drosophila, such as the formation of the heart wall; and we're almost certain the same genes are working to make mammalian hearts.”
The goal of the research, which will run for five years, is to understand how the fly heart is put together and identify genes working in the process. The fly heart is comprised of 104 cells arranged in pairs along the length of the body. It is a simple beating tube with three sections termed the anterior aorta, posterior aorta and the heart chamber.
In the fly circulation, blood enters the heart chamber and is pumped forwards through the aorta to the brain. Different regions of the heart express different genes in a very similar manner to a vertebrate heart at its early stages of development. Cripps' team will identify genes that control the blood flow into the heart chamber and will also study how genes construct the heart wall.
“Tinman is a gene expressed in many heart cells,” said Cripps. “It's required for flies to survive, since if you knock out Tinman or if it's not expressed, there is no heart formed. Tinman is a very important gene since it functions to switch on a large number of other cardiac genes, however we currently know of only a few of its gene targets.”
A gene very similar to Tinman is also found in the human heart and performs a similar role in its development.
“It's important because many human heart defects arise from gene mutations involved in making the heart,” said Cripps. “Mutations in the gene called NKX 2.5 or the mammalian Tinman, are known to cause congenital heart defects in humans. One of the goals of our studies is to identify which genes are switched on by Tinman so we can understand the details of the human disease.”
Cripps is one of a number of scientists worldwide who use their Drosophila research to unravel the processes of human development. Such research has helped pinpoint genetic problems in vertebrates and can lead scientists to a better understanding of how a large number of hereditary diseases develop in humans.
This article was originally published in "UNM Today: Campus News and Information" (http://www.unm.edu/~market/cgi-bin/) on March 9, 2005 by Steve Carr (505/277-1821).