DNA Methylation and Gene Expression

Posted: March 12, 2013 in Uncategorized
Tags: , , , , ,

For those of you who have not read my article concerning epigenetics, I encourage you to read it here, https://geneticpotential.wordpress.com/2013/02/27/epigenetics-understanding-gene-expression/.

 

DNA methylation in a nutshell is the addition of a methyl group to DNA nucleotides.  The methylation process is a way that our body turns off certain genes.    Not all genes are turned on at the same time in the human body and DNA methylation may be a confounding factor in the gene expression seen in Huntington’s Disease (HD).

Researchers have been studyng how disease may be correlated to errors in methylation.  Specifically in trinucleotide repeat disorders DNA methylation may play a role in the stability of the trinucleotide.  Remember HD is a trinucleotinde repeat disorder and those diagnosed have expansions of the CAG portion of the DNA strand.  DNA methylation may also play a role in somatic and germinal cell stability. 

Germinal mutations are mutations of genes in a germ cell and a somatic mutation is a mutation of genes in all other cells.  Research has shown that the CAG repeat expansion in HD is due to somatic instability and potentially finding a way to alter the instability would lead to therapeutic advantages (Swami, 2009).  This study as well as others show that this somatic instability is also related to the age of onset of the symptoms of the disease.

The most promising treatment coming out of Western medicine seems to be the use of antisense oligonucleotides (ASO).  These are gene silencing drugs that act upon the defect in the Huntington gene.  Basically, they destroy the defective mRNA before it can ever be transcribed into DNA. 

In monkeys they injected the drugs into the spinal fluid and saw a reversal of symptoms as well as a decreased amount of the abnormal Huntington protein.  The only issue now is making sure that the drugs do not block the normal Huntington protein, as it is important for human development (http://www.genengnews.com/gen-news-highlights/antisense-oligos-reverse-huntington-disease-phenotype-in-mice/81246940/).

As this is promising, what if we can attack this issue from the start by increasing DNA methylation?  This can increase our natural gene silencing abilities.  If we can silence the production of the abnormal Huntington protein without affecting the normal Huntington protein we may be able to silence the symptoms of the disease.  If anything it can prolong the onset of symptoms, or work in conjunction with the new drugs to increase their efficacy.  There will be much more to come on this topic to come.

 

 

http://www.societyns.org/runn/2010/pdfs/Portela%20Nat%20Biotech%20review%202010%20epigenetic%20mod.pdf

http://www.nature.com/scitable/topicpage/the-role-of-methylation-in-gene-expression-1070

http://hmg.oxfordjournals.org/content/18/16/3039.full
http://bura.brunel.ac.uk/bitstream/2438/7217/2/Fulltext.pdf

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Comments
  1. Andy says:

    Great post, I eagerly await further posts on this topic. Gene expression and epigenetics are super interesting and complicated. I am currently doing a bit of research on my own regarding neuro-degenerative diseases (Frontotemporal Lobar Dementia, and AD) and how they can be prevented/delayed or reduce severity with lifestyle factors like diet, exercise, stress reduction etc. DNA Methylation plays a role as well.

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