Why are these homeobox genes important for fat? "We believe these genes actually program those fat cells to respond differently to different hormones and other signals," Smith says.
Stem cells show fat is preprogrammed for its location
In the course of their work, Smith and his team also isolated stem cells from belly and thigh fat and grew them in laboratory dishes. This was a nice control because fat cells in a dish aren't influenced by nerves, hormones, or other outside signals.
Yet the researchers still saw the same location-specific differences in gene activity in the fat that developed from these stem cells. That result told them that the cells are preprogrammed. In other words, belly fat and thigh fat are genetically destined for their final location during development. It's not a difference that's acquired over time, as a result of diet or environmental exposure.
A new way of thinking about fat
Medically speaking, says Smith, it's important to understand these differences and how they arise. "Even though many women hate having large hips and thighs, that pear shape actually reduces their risk of heart disease and diabetes. In fact, women who have heart attacks tend to have more belly fat than thigh fat."
This research marks a new way of thinking. "Most people want to stop belly fat. But the problem is not just the fatit's the location. Belly fat is just a marker of the problem. The real issue is in inability to store that fat on the hips and thighs," he continues.
Smith hopes that future studies aimed at understanding the fundamental differences in these fat depots could lead to specific treatments aimed at the regions that contribute most to the complications of obesity.
|Contact: Heather Buschman|
Sanford-Burnham Medical Research Institute