Whether a gene is switched on or off is dependent on a variety of mechanisms in the nucleus of a cell. One such mechanism is DNA methylation – this is how many small molecules, methyl groups, are attached to the DNA. When there is a high level of methylation other molecules, such as enzymes, can't get to the DNA to carry out transcription. DNA methylation therefore switches the gene off.
Professor Juleen Zierath and her colleagues at the Karolinska Institute in Sweden examined how exercise affected the level of DNA methylation on certain genes. The researchers took small pieces of muscle, called biopsies, from the legs of men before and after they did an hour of exercise. "We provided evidence that acute exercise leads to transient changes in DNA methylation in adult skeletal muscle", explained Professor Zierath. The group observed that specific genes were turned on by a decrease in the number of methyl groups attached to them.
The effects were not permanent; the number of methyl groups returned to normal within 48 hours. It is believed that the loss of methyl groups from these genes plays a role in allowing the muscle to adapt to exercise.
About the scientist: Professor Juleen Zierath
What motivated you to become a scientist?
I was an athlete and interested in improving my own performance during competitions. I became fascinated with exercise physiology – how the body adapts to different types of exercise training. I entered into a research group that was focused addressing questions related to what defines the limit of exercise performance. So my early motivation was very personal and directly related to my desire to be a better athlete.
What is the best thing about the research you do?
I have a lot of freedom to decide what questions I wish to address in my work. Through this, I have an opportunity to meet many talented and highly motivated people from all ends of the Earth who wish to make a difference and find new ways to improve the quality of life for people with Type 2 diabetes. For example, this particular study was performed by a team of scientists from France, China, Denmark, Ireland and Sweden. So science is very international and this has been enriching. Plus, every day is different, so it is never a boring life!
