Stress hormones trigger numerous reactions in the organism
Scientists at the Max Planck Institute for Molecular Genetics (MPIMG) in Berlin are studying the reactions in the body that are triggered when stress hormones are released. Typical stress reactions include increased heart rate, accelerated breath and rising blood pressure. The researchers report how stress hormones are released into the bloodstream and transported to the various tissue and cell types in the body. Ultimately, the entire body is exposed to these hormones.
Although the entire organism is confronted with the same stress hormones, cells react with different physiological measures. For example, fat cells mobilize energy reserves and cells of the immune system slow down their activity. Why the cells react so differently to stress has so far been largely unclear. Sebastiaan Meijsing and his team have discovered in their research a so-called enhancer that has a regulatory function and can influence the activity of genes.
How do the cells react to stress signals?
The MPIMG research team examined in particular the so-called enhancers. These are certain regions in the genome that have a regulatory function and can influence the activity of genes. The scientists discovered that a single enhancer in different cell types can regulate different stress responses.
The same enhancers can cause different reactions
To investigate the function of the enhancers in more detail, the research team removed the enhancers from the genome of lung cells. They then checked how the behavior of the cells changes when they are exposed to stress hormones. Based on these studies, several enhancers were identified who are responsible for the stress-related changes. The scientists then checked the activity of the same enhancers in bone cells and surprisingly found that the same enhancers trigger different reactions. For example, a DNA section (transcript) was activated in the lung cells, which is a long distance from the enhancer. In contrast, the same enhancers activated a transcript in the immediate vicinity in bone cells.
Toaster or kettle?
In a press release from the Max Planck Institute in Berlin, Sebastiaan Meijsing tries to make the research results understandable even for laypeople: "Imagine that you only have a socket with which you can operate either your toaster or your kettle," says Meijsing. Both would work, but you have to choose a device. The situation is similar in these two cell types. The investigated enhancer could activate either the adjacent or the more distant DNA section.
How does the enhancer decide which section to activate?
"For the region we examined, there is evidence that the folding of the genome in the bone cells enables the enhancer to interact with the neighboring DNA region," explains Meijsing. In contrast, the genome in the lung cells is folded in such a way that the enhancer can only interact with the more distant section of the DNA. Such a “reuse” of existing enhancers for different genes enables the organism to generate different products in response to stress.
The three-dimensional folding of the genome
Different three-dimensional folds of the genome occur when different cell types are formed. These differences enable different interaction processes between enhancers and the genes or the transcripts. According to Meijsing, this different use of the same enhancers in different cell types can contribute to the diverse physiological stress reactions in the human body.
Coping with stress
Many forms of stress can have a negative impact on health. Especially people who are exposed to frequent and persistent stress at work or at home should learn how to deal with it. Various exercises and measures for reducing stress are available for this. Proven relaxation procedures include:
- Autogenic training,
- Progressive muscle relaxation,
- and meditation.