Another experiment reduced the expression of one FIT gene in mouse fat cells. A drastic reduction in fat droplet production was found in those cells.
Then, the researchers injected genetic material designed to block activity of the genes into an experimental animal, the zebrafish. The fish were fed a high-fat diet for six hours, but examination of their livers and intestines found almost no fat droplets.
Mouse models that lack the genes are being developed to see what happens to an animal that cannot package its fats, Silver said. The question is, "Where will it go if the body can't store it?" he said.
There are two possibilities -- One is that "the body responds in a positive way and burns it," Silver said. "The other outcome is some kind of toxicity, with the fat deposited elsewhere. At the moment, we don't know the answer to that question."
Now that the genes have been identified, it should be possible to develop drugs that modify their activity -- drugs that could be useful not only against obesity but also against conditions such as diabetes and heart disease.
"We could engineer the very fundamental process by which all life stores fat," Silver said. "That is a very basic discovery."
It is a "seminal discovery," said Dawn L. Brasaemle, an associate professor of nutritional sciences at Rutgers University, who has been working on lipid droplets since they were first described in the early 1990s. The field is so new that the first scientific meeting on them was just held this past summer, she said.
The first challenge facing Silver is to learn how these genes work with others involved in lipid packaging, Brasaemle said. "Then we have to know what is their importance for health," she added. "Is there a way to manipulate them with ph
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