How enzyme lowers weight gain

Obesity can be prevented with healthy diet and regular exercise. People tend to gain weight as they age, particularly around the stomach.

The researchers were led by Dr. Jay H. Chung, Ph.D., head of the Laboratory of Obesity and Aging Research at the National Heart, Lung, and Blood Institute, which is a part of the NIH.

Specific enzyme inhibitor lowers weight gain by 40 percent
Chung and team investigated the biochemical transformations that take place in animals in their middle age.

Looking at animals that were the equivalent of 45 human years old, Chung and team found that an enzyme - called DNA-dependent protein kinase (DNA-PK) - becomes more active with age.

Furthermore, the researchers found that DNA-PK turns nutrients into fat and lowers the number of mitochondria.

The younger we are, the more mitochondria we have in our bodies. From midlife onward, however, the number of mitochondria starts to decrease.

 It is known that a lower number of mitochondria can lead to obesity, and mitochondrial dysfunction has been associated with a decrease in one's ability to exercise.

To further understand the role of the DNA-PK enzyme, Chung and team tested its effect on two groups of mice. Both groups were fed a high-fat diet, but one group received an inhibitor that blocked the DNA-PK enzyme, while the other group did not.

The group that received the DNA-PK-inhibiting drug gained 40 percent less weight than those that did not receive the drug. Additionally, the drug increased aerobic fitness and decreased the rate of obesity and type 2 diabetes in obese, middle-aged mice.
Finally, the inhibitor also increased the number of mitochondria in the mice's skeletal muscle.