Researchers recruited slightly overweight men in their 30s
and 40s who led an inactive lifestyle. After six months of weekly spin classes
and group aerobics, they all showed improved fitness and weight loss due to the
exercise regime, despite not making changes to their normal daily tasks or diets.
This may be an expected result, but interestingly, biopsies of fat tissue showed
differences in the regulation of 7,663 genes, suggesting that exercise was
driving epigenetic changes.
'Our study shows the positive effects of exercise, because
the epigenetic pattern of genes that affect fat storage in the body changes',
says Dr Charlotte Ling, from Lund University in Sweden, who led the research.
Epigenetics is the study of how changes in our environment
influence the regulation of our genes. This can affect how cells function and there
is evidence to suggest these changes can be linked to lifestyle-related diseases.
One epigenetic mechanism is DNA methylation, where methyl groups on DNA prevent
gene transcription, silencing gene expression. Levels of DNA methylation in the
fat tissue of the 23 volunteers were analysed and changes in mRNA expression
monitored. The team found that 7,663 genes were differently methylated in fat
tissue as a direct effect of exercise.
Dr Ling's group focused on three genes which showed
increased levels of DNA methylation after exercise and have been previously
linked to type 2 diabetes, metabolic syndrome and obesity. In vitro assays were
used to confirm the gene-silencing effect of DNA methylation.
'We found changes in those genes too, which suggests
that altered DNA methylation as a result of physical activity could be one of
the mechanisms of how these genes affect the risk of disease', says Tina
RÃ¶nn, who conducted the study.
It is important to note that this study was performed in a
relatively small trial cohort. The absolute changes in DNA methylation in
response to exercise were modest, but Dr Ling argues that the large number of
sites of methylation found on different genes could contribute to an overall
More than one billion people worldwide are now categorised as obese
and there is a clear link between obesity and type 2 diabetes. Understanding
the underlying genetic profiles of these disorders, and how epigenetic factors
such as exercise can alter gene expression may one day suggest new strategies
for targeted therapies.