Research Reveals How Cells Store Fat

By Ed Edelson
HealthDay Reporter
Tuesday, December 18, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

MONDAY, Dec. 17 (HealthDay News) -- Researchers say they've spotted the genes that cells use to store fats, a discovery that might someday lead to new weight-loss therapies.

The genes produce proteins that are key to fat storage, the U.S. researchers report in this week's issue of the Proceedings of the National Academy of Sciences.

"We know from our studies that if you reduce the level of these proteins in cells, the cells lose the ability to store fat," said senior researcher David Silver, an assistant professor of biochemistry at Albert Einstein College of Medicine in New York City.

As Silver explained, the genes "store fat in the form of droplets as an energy reserve for later use. These make proteins involved in fundamental processes, and they are conserved throughout evolution."

Searching databases, Silver and his colleagues have established that the two genes they identified -- dubbed FIT1 and FIT2 -- are present in the most primitive members of the advanced cell type called eukaryotes, which make up the human body. "One ancient gene goes all the way back to yeast," Silver said.

Other scientists had already identified genes responsible for synthesizing fat within cells, he noted. The new discovery describes the genes that package that fat into liquid droplets within a layer of molecules called phospholipids and proteins.

Both genes produce proteins that consist of more than 200 subunits called amino acids, and the two genes are 50 percent similar to one another. The amino acid chains of the FIT genes do not resemble those of any other protein found in any species, the researchers said.

Meanwhile, several series of experiments have confirmed the role of the FIT genes in fat storage, Silver said.

In one experiment, extra copies of the genes were inserted in human cells. The rate of fat synthesis was unchanged in those cells, but the number of fat droplets produced in those cells increased four- to sixfold.

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.