Fruit Flies Can Shed Light On High Cholesterol, Obesity In Humans
How do fruit flies get high cholesterol and become obese? The same way as people do – by eating a diet that’s too rich in fats.
More importantly, according to two new studies led by a University of Utah human geneticist, fruit flies use the same molecular mechanisms as humans to help maintain proper balances of cholesterol and a key form of stored fat that contributes to obesity. The findings mean that as researchers try to learn more about the genetic and biological processes through which people regulate cholesterol and fat metabolism, the humble fruit fly, also called Drosophila, can teach humans much about themselves.
“Not a lot is known about these regulatory mechanisms in people,” says Carl S. Thummel, Ph.D., professor of human genetics at the U of U School of Medicine and senior author on the two studies. “But we can learn a lot by studying metabolic control in fruit flies and apply what we learn to humans.”
High cholesterol and obesity, which affects an estimated 25 percent to 30 percent of the U.S. population, are linked to heart disease, diabetes, and other diseases that take huge tolls on health and add billions of dollars to the nation’s medical bills. Understanding the processes that regulate cholesterol and fat in humans could be critical for addressing those health risks in people, Thummel believes.
The two studies identify a nuclear receptor, DHR96, which plays a critical role in regulating the balance or homeostasis of cholesterol and another fat molecule called triacylglycerol (TAG). Nuclear receptors are proteins that sense the presence of chemical compounds within cells. DHR96 corresponds closely to a nuclear receptor in humans, called LXR, that is known to regulate cholesterol levels.
In a study published Dec. 2 in Genes & Development, Thummel and colleagues at the U of U and two Canadian universities show that DHR96 helps regulate cholesterol in fruit flies by binding with this compound. When this binding occurs, it allows DNA to be read, which switches genes on and off that help maintain proper levels of cholesterol, according to Thummel, who also holds an H.A. and Edna Benning Presidential Endowed Chair in Human Genetics. Read more
Chocolate Consumption Linked To Depression, Study
Women and men eat more chocolate as depressive symptoms increase, suggesting an association between mood and chocolate, say researchers at the University of California School of Medicine in San Diego.
Results of this paper, co-authored by Beatrice Golomb, MD, PhD, associate professor of medicine at UCSD School of Medicine, will appear in the April 26 issue of Archives of Internal Medicine.
“Our study confirms long-held suspicions that eating chocolate is something that people do when they are feeling down,” said Dr. Golomb. “Because it was a cross sectional study, meaning a slice in time, it did not tell us whether the chocolate decreased or intensified the depression.”
Golomb and her colleagues examined the relationship of chocolate consumption to mood in an adult study sample of about 1,000 subjects who were not on antidepressant medications and did not have any known cardiovascular disease or diabetes. Participants were asked questions regarding how many servings of chocolate they ate in a week, and were screened using the Center for Epidemiologic Studies Depression Scale (CES-D) to measure mood. Read more