Nevco News
May 2009
Volume 2, Issue 5
The Link Between Obesity and Genetics
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Researchers have uncovered new evidence suggesting factors other
than genes could cause obesity, finding that genetically
identical cells store widely differing amounts of fat depending
on subtle variations in how cells process insulin. Learning the precise mechanism responsible for fat storage in cells could lead to methods for controlling obesity. "Insights from our study also will be important for understanding the precise roles of insulin in obesity or Type II diabetes," said Ji-Xin Cheng, an assistant professor at Purdue. Findings indicate that the faster a cell processes insulin, the more fat it stores. Other researchers have suggested that certain "fat genes" might be associated with excessive fat storage in cells. However, the Purdue researchers confirmed that these fat genes were expressed, or activated, in all of the cells, yet those cells varied drastically - from nearly zero in some cases to pervasive in others - in how much fat they stored. "This work supports an emerging viewpoint that not all |
biological information in cells is encoded in the genetic
blueprint," said Thuc T. Le, a postdoctoral fellow at Purdue. The researchers determined that these differences in fat storage depend not on fat-gene expression but on variations in a cascade of events within an "insulin-signaling pathway." The pathway enables cells to take up glucose from the blood. "Only one small variation at the beginning of the cascade can lead to a drastic variation in fat storage at the end of the cascade," Cheng said. The researchers conducted "single cell profiling." Single cell profiling allows researchers to precisely compare the inner workings of individual cells, whereas the conventional analytical approach in biochemistry measures entire populations of cells and then provides data representing an average. "In this case, we don't want an average. We need to find out what causes fat storage at the single-cell level so that we can compare one cell to another," Le said. "By profiling multiple events in single cells, we found that variability |
in fat storage is due to varied rates of insulin processing
among cells." "This particular type of cell culture has been used to study the molecular control of obesity for the past 35 years," Cheng said. "Researchers have observed tremendous variability in how much fat is stored in cells with identical genes, but no one really knows why. Our findings have shed some light on this phenomenon." Insulin attaches to binding sites on cell membranes, signaling the cells to take up glucose from the blood. Cells that are said to be resistant to insulin fail to take up glucose, the primary cause of Type II diabetes, a medical condition affecting nearly 24 million Americans. About two-thirds of U.S. adults are overweight, and nearly one-third obese. The research, which has been funded by the National Institutes of Health, is ongoing. Future work may seek to pinpoint specific events in the insulin-signaling cascade that are responsible for fat storage. Purdue University (2009, April 15). Factors Other Than Genes Could Cause Obesity, Insulin Study Shows. ScienceDaily. Retrieved April 15, 2009 |
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