On Genetics Terminology – DON’T PANIC!
This is more of a research article than most. However, if you have never studied genetics, microbiology, or perhaps even taken biology as a matric subject then you are in the majority! Many people scan through bits of text, see a couple of scientific terms and literally switch off or move swiftly on.
As an aside, I recall some of the people in my school having a similar knee jerk response just to the word ‘mathematics’. When I do a bit of neuro-psychological testing – basically IQ testing – with clients today, I find they do much better in the mathematics subtest if I don’t label it as maths when we begin the section!
Anyhow, feel free to first read my short article on Genetics 101, which provides a brief, easily understandable, layman to layman overview of (at least a minuscule subsection) of genetics. It will cover everything you might need to know to get the maximum out of this article.
Gene Expression
Would you believe that if you are healthy but haven’t been exercising then just one brief yet intense spell of exercise actually changes your DNA! It appears that DNA methylation (or DNA de-methylation) is activated and plays a role in exercise based gene expression. Some of the genes activated lead to processes that break down calories and fat or help stabilise blood glucose.
Now, this is actually fascinating stuff. It had been thought for a long period of time that once a cell became an adult cell gene methylation stabilised and then gene expression like genetic structure was fixed.
Put differently it was thought that we inherit a set of genes and then are stuck with them!
However, it turns out that although your genetic make-up is fixed, the presence (or absence) of certain methyl groups at certain DNA positions can actually affect gene expression.
Three Studies Demonstrating That Exercise Alters Genetic Expression
Study 1
The research showed that in certain genes used in energy metabolism, like PGC-1α, PPAR-δ and PDK4, the exercise resulted in DNA demethylation in certain genetic areas, and this facilitated the transcription of particular genes. The degree of methylation also correlated with the intensity of the exercise.
Now generally when methyl groups are present (methylation) in most circumstances this serves to limit genetic expression. The demethylation allowed genetic expression of the metabolic (fat burning) genes PGC-1α, PPAR-δ and PDK4.
Study 2
This study examined the ramifications of exercise on genetic expression. It examined weight loss in 35 year old healthy but slightly overweight men over 6 months of exercise. In fact, the research discovered epigenetic changes in around 7000 genes (we apparently have between 20 000 and 25 000). Epigenetic changes are environmental changes that lead to changes in the way that certain genes are ‘read’, and therefore alter genetic expression. Some of these areas contained sites with obesity candidate genes.
Consequently, demethylation allowed for greater calorie and fat burning!
Study 3
This study examined the ramifications of exercise on genetic expression in more detail. It utilised normal weight subjects who led a sedentary lifestyle, as well as a second group consisting of individuals with or without diabetes type 2. The subjects were placed on a 6 month exercise program and then examined on both weight loss and diabetes measures.
Global DNA methylation changed, and 17,975 individual CpG sites in 7,663 unique genes showed altered levels of DNA methylation. Equally, altered mRNA expression occurred at 1/3 of gene regions with altered DNA methylation, including RALBP1, HDAC4 and NCOR2. 18 obesity and 21 type 2 diabetes candidate genes had CpG sites with differences in DNA methylation in response to exercise, including TCF7L2 and KCNQ1. There was a simultaneous alteration in mRNA expression for 6 of those genes.
The researchers concluded ‘exercise induces genome-wide changes in DNA methylation in human adipose tissue, potentially affecting adipocyte metabolism.’
Simply put, despite genetic structure being unalterable, exercise induced genetic expression can help both genetically obese and individuals with more normal metabolism to break down calories and fat deposits.
Exercise Helps With Diabetes Type 2
Very similar to the research on obesity, the same study mentioned above also demonstrated that exercise without weight loss improves insulin sensitivity in both lean and obese sedentary individuals!
References
- Radom-Aizik S1, Zaldivar F Jr, Leu SY, Cooper DM. 2009. “Brief bout of exercise alters gene expression in peripheral blood mononuclear cells of early- and late-pubertal males”. Pediatr Res.
- Ronn TS, et al 2013. “Genes associated with obesity or type 2 diabetes display altered levels of DNA methylation in human adipose tissue in response to exercise” EASD 2013 Conference.
- Rönn T, Volkov P, Davegårdh C, Dayeh T, Hall E, Olsson AH, Nilsson E, Tornberg A, Dekker Nitert M, Eriksson KF, Jones HA, Groop L, Ling C. 2013. “A six months exercise intervention influences the genome-wide DNA methylation pattern in human adipose tissue”. Plos Genetics
- Schwenk RW, Vogel H, Schürmann A. 2013. “Genetic and epigenetic control of metabolic health”. Molecular Metabolism.
The Endocrine Society. “Exercise Alone Shown To Improve Insulin Sensitivity In Obese Sedentary Adolescents.” ScienceDaily. ,11 September 2009.
www.sciencedaily.com/releases/2009/09/090901082406.htm
