Health and Medical News and Resources

General interest items edited by Janice Flahiff

Charting the Chemical Choreography of Brain Development

Diagram of the various parts of the brain of a...

Diagram of the various parts of the brain of a six-week old embryo (Photo credit: Wikipedia)

 

 

 

 

 

From the 27 August 2013 Director’s blog item (National Institutes of Health)

 

Once in a while a research publication reveals an entirely new perspective on a fundamental issue in biology or medicine. Today’s blog is about such a paper. The story, though complex, is very significant.

The choreography of human brain development is amazing, but quite mysterious. Today’s post highlights a study [1] that reveals the locations of some of the chemical choreographers that collaborate with DNA to orchestrate these fancy moves in the brain.

This complex developmental dance starts in the womb as our brain cells arise, migrate to their proper locations, and mature. By the time we’re born, each of us has close to 100 billion of these cells, called neurons. But that’s not all. The brain also contains lots of other cell types—especially glia. Glial cells were previously thought to act primarily as servants to the neurons, but they’re actually more like partners. Our birth inventory is just the first act. Over the course of our lives, our experiences and environment continue to shape and re-shape the brain’s connections, albeit in varying paces and patterns.

The millions of chemical tags that modify or mark the genome tell it what to do, and when and where to do it. Taken together, we call this diverse collection of chemical cues the “epigenome.”

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Just as genetic mutations can lead to disease, glitches in DNA methylation may also trigger or increase the severity of brain disorders. Several studies have already linked abnormal methylation with disorders like schizophrenia, and conditions like Traumatic Brain Injury. This research is particularly exciting because these DNA methylation tags are not permanent. So, if we discover patterns of methylation that cause particular brain diseases, we can develop strategies to restore the healthy epigenetic profile—in effect, to bring those errant brain cells back in step with the dance of normal brain development.

Sketched image of a brain, neuron, glia, DNA, methylation sites, and a graph of methylation decreasing over time

Caption: Researchers mapped methylation sites in genomes of neurons and glia in the frontal cortex. mCH methyl tags, or non-CG methylation (purple stars), were absent at birth, but were added rapidly during the first few years of life and then more slowly until about age 30. After age 50, the number of mCH tags declined.
Credit: Eran Mukamel, Salk Institute

This study is a powerful example of how recent technological advances are revealing the secrets and complexities of the human brain—a process we hope to accelerate with the start of the BRAIN initiative!

References:

[1] Global epigenomic reconfiguration during mammalian brain development. Lister R, Mukamel EA, Nery JR, Urich M, Puddifoot CA, Johnson ND, Lucero J, Huang Y, Dwork AJ, Schultz MD, Yu M, Tonti-Filippini J, Heyn H, Hu S, Wu JC, Rao A, Esteller M, He C, Haghighi FG, Sejnowski TJ, Behrens MM, Ecker JR. Science. 2013 Aug 9;341(6146):1237905.

[2] Sequence data can be downloaded from National Center for Biotechnology Information GEO (GSE47966). The analyzed data is also available for browsing.

 

 Read the entire article here

 

 

 

 

August 28, 2013 Posted by | Biomedical Research Resources, Medical and Health Research News, Psychiatry | , , , , , , | Leave a comment

Childhood Poverty, Stress, May Shape Genes And Immune System

From the 22 October 2012 article at Medical News Today

A University of British Columbia and Centre for Molecular Medicine and Therapeutics (CMMT) study has revealed that childhood poverty, stress as an adult, and demographics such as age, sex and ethnicity, all leave an imprint on a person’s genes. And, that this imprint could play a role in our immune response. …

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Known as epigenetics, or the study of changes in gene expression, this research examined a process called DNA methylation where a chemical molecule is added to DNA and acts like a dimmer on a light bulb switch, turning genes on or off or setting them somewhere in between. Research has shown that a person’s life experiences play a role in shaping DNA methylation patterns. ..

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“We found biological residue of early life poverty,” said Michael Kobor, an associate professor of medical genetics at UBC, whose CMMT lab at the Child & Family Research Institute (CFRI) led the research. “This was based on clear evidence that environmental influences correlate with epigenetic patterns.” ..

[youtube=[youtube=http://www.youtube.com/watch?v=JaNH56Vpg-A]]

http://www.youtube.com/watch?v=S6tSndex0CM&feature%5D

 

October 29, 2012 Posted by | environmental health, Uncategorized | , , , , , | 1 Comment

Environment And Diet Leave Their Prints On The Heart

From the 30 November 2011 Medical News Today article 

A University of Cambridge study, which set out to investigate DNA methylation in the human heart and the ‘missing link’ between our lifestyle and our health, has now mapped the link in detail across the entire human genome.

The new data collected greatly benefits a field that is still in its scientific infancy and is a significant leap ahead of where the researchers were, even 18 months ago.

Researcher Roger Foo explains: “By going wider and scanning the genome in greater detail this time – we now have a clear picture of the ‘fingerprint’ of the missing link, where and how epigenetics in heart failuremay be changed and the parts of the genome where diet or environment or other external factors may affect outcomes.” …

DNA methylation leaves indicators, or “marks”, on the genome and there is evidence that these “marks” are strongly influenced by external factors such as the environment and diet. The researchers have found that this process is different in diseased and normal hearts. Linking all these things together suggest this may be the “missing link” between environmental factors and heart failure.

The findings deepen our understanding of the genetic changes that can lead to heart diseaseand how these can be influenced by our diet and our environment. The findings can potentially open new ways of identifying, managing and treating heart disease.

The DNA that makes up our genes is made up of four “bases” or nucleotides – cytosine, guanine, adenine and thymie, often abbreviated to C, G, A and T. DNA methylation is the addition of a methyl group (CH3) to cytosine.

When added to cytosine, the methyl group looks different and is recognised differently by proteins, altering how the gene is expressed i.e. turned on or off.

DNA methylation is a crucial part of normal development, allowing different cells to become different tissues despite having the same genes. As well as happening during development, DNA methylation continues throughout our lives in a response to environmental and dietary changes which can lead to disease.

As a result of the study, Foo likens DNA methylation to a fifth nucleotide: “We often think of DNA as being composed of four nucleotides. Now, we are beginning to think there is a fifth – the methylated C.”

Foo also alludes to what the future holds for the study: “…and more recent basic studies now show us that our genome has even got 6th, 7th and 8th nucleotides… in the form of further modifications of cytosines. These are hydroxy-methyl-Cytosine, formylCytosine and carboxylCytosine = hmC, fC and caC! These make up an amazing shift in the paradigm…”

As in most studies, as one question is resolved, another series of mysteries form in its place. The study shows that we are still on the frontier of Epigenetics and only just beginning to understand the link between the life we lead and the body we have. 

DNA Methylation in E. coli

DNA methylation in E.coli

November 30, 2011 Posted by | Consumer Health, Medical and Health Research News, Nutrition, Public Health | , , , , , , | Leave a comment

   

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