How do epigenetic modifications influence gene expression, and what are the implications of these changes in health and disease?"

Question

Epigenetic modifications, such as DNA methylation and histone changes, regulate gene expression by altering the structure of DNA and chromatin, without changing the genetic code. These modifications can turn genes on or off. In health and disease, epigenetic changes are involved in development, cancer, neurological disorders, and can be influenced by environmental factors like diet and stress, potentially leading to inherited health conditions.

Answer 1

Epigenetic modifications change how often, if ever, a gene is expressed. Epigenetic modifications operate in 2 ways: Methylation and Histone Changes. To understand Methylation and Histones, we first have to understand how DNA exists in a cell. Within the nucleus, DNA can be found either wrapped up tight around histones, effectively 'in storage', or unwound and prepared for transcription. Genes can only be expressed if their section of DNA is available for transcription. If the DNA is wrapped up around histones, it cannot be transcribed, and therefore cannot be expressed. Changes in histone shape or availability may make it easier or more difficult for DNA to wrap around it, making the affected genes less or more available for transcription and therefore expression.

Methylation, however, works a little differently. When a gene is methylated, a methyl group is added to a DNA molecule, effectively changing the structure of the DNA without changing the code of the DNA itself. When the structure changes, it is more difficult for transcription (and therefore gene expression!) to occur because transcription factors and proteins either no longer recognize or cannot connect with the gene to begin transcription. In this way, Methylation can effectively turn a gene 'off' without deleting or changing the gene itself.

Histone changes and Methylation can occur due to a variety of factors, including environmental factors like diet and stress, as you've stated. Changes in a gene expression can affect a large variety of diseases, but I will provide a couple of examples to help you understand the larger picture. In cancer research, a gene that increases risk of cancer is called an oncogene, while a gene that helps prevent cancer May be called a tumor suppressor gene. If oncogenes are under-methylated (hypo-methylated), it may lead to more frequent expression of these cancer causing genes, and more cancer. If tumor suppressor genes are over-methylated (hyper-methylated), it may lead to less frequent expression of cancer mitigating genes, and more cancer.

An interesting fact about these epigenetic changes is that although they are not DNA or RNA, they can be passed down to future generations. A great example of this is The Dutch Hunger Winter Study. In this study, it was found that people who experienced famine and extreme hunger experiences epigenetic changes that slowed metabolism, helping to store any calories they were able to and minimize energy waste. These epigenetic changes were passed onto their children and grandchildren, who in times of abundance were more likely to experience overweight and obesity. In this diet example, the epigenetic changes that helped the first generation survive their environment may have lead to disease in the second and third generation because their environment provided more access to higher calorie foods.

Another example is the effect of extreme and chronic stress. Epigenetic changes may occur in people under extreme duress, and passed onto further generations. This is one factor that might explain intergenerational stress. Children, grandchildren, and many following generations may inherit epigenetic changes that increase anxiety, depression, and susceptibility to PTSD.

I hope this explanation helped to expand more on your definition of epigenetic changes, how they happen, and how they affect us. It's amazing that such tiny changes in microscopic molecules can have such a profound effect on our lives!

Answer 2

Epigenetic modifications are like little switches or markers that sit on top of your DNA and tell your cells which genes to turn on or off. These changes don’t alter the actual DNA sequence but can control how much or how little a gene is expressed.

One way this happens is through **DNA methylation**, where small molecules called methyl groups are added to the DNA. This can block certain genes from being read, effectively turning them "off." Another way is through **histone modification**—histones are proteins that DNA wraps around, and adjusting them can make genes more or less accessible for the cell to use.

These modifications are influenced by your environment, lifestyle, and even things like stress or diet. For example, if you’re exposed to a lot of stress, it might change how certain genes are expressed, potentially impacting your mental health.

In terms of health and disease, these changes can have big effects. If genes that protect against cancer are turned off through epigenetic modifications, it can increase the risk of developing the disease. On the other hand, certain epigenetic therapies are being developed to "reset" these switches and treat conditions like cancer or even autoimmune diseases.

Think of it like a light dimmer: epigenetic modifications control the brightness (or activity) of genes, and when the dimmer is off or too bright in the wrong places, it can lead to health problems.

Answer 3

First and foremost, epigenetic modifications are changes to the DNA that occur on top of, epi, the nucleic acids. So these modifications are things like other biochemicals added to the DNA to influence how things like transcription and translation, aka gene expression, will occur.

You already have the answer in your paragraph above.

You mention that these epigenetic modifications regulate expression by changing the DNA/chromatin structure, while leaving the genetic code intact. As you say, these modifications can turn genes on or off. You have also mentioned that this influences health and disease because environmental factors "are involved" in development, etc, all the way up to environmental factors.

To make your answer better, I would ask:

1. how, or when are these epigenetic changes made?
2. hint: remember that epigenetic modifications can turn genes 'on' or 'off.' Think of them as a switch, or dial for the genes.
3. how does making a certain epigenetic change influence the following?
4. cancer -- did something go right, or did something go wrong? what might it be?
5. development -- why could you want to turn genes on or off during this process?
6. Environmental factors -- what might be the body's response to an environmental factor on a cellular, and more specifically, epigenetic level?