Genetics of human brain

[Hans de Vries]

How many genes are involved, solely or mostly, in the functioning of human brain?

[John Cuthber]

All of them; at least indirectly.

[Xalatan]

That's an interesting question. Wikipedia says there are an estimated 20,000-25,000 protein-coding genes in the human genome. What percentage of this regulates brain function?

 

Another way to think about it may be to exclude functions that the brain doesn't perform. Eg. Secrete insulin, exocrine digestive enzymes, turn over urea, secrete surfactant, produce renin, ACE, aldosterone, cortisol, androgens. Structurally there may be less collagen and muscle fibres in the brain matrix since glia fulfils the role but meninges would be composed of connective tissue.

[CharonY]

It is not that easy. There are insulin receptors in brain tissue, as well as insulin itself (although it could be of peripheral origin). Point is that many proteins, especially those involved in signaling can play varied roles in many tissues.

[Xalatan]

Quoting the National Institute of Neurological Disorders and Stroke, "At least a third of the approximately 20,000 different genes that make up the human genome are active (expressed) primarily in the brain. This is the highest proportion of genes expressed in any part of the body. These genes influence the development and function of the brain, and ultimately control how we move, think, feel, and behave".

 

http://www.ninds.nih.gov/disorders/brain_basics/genes_at_work.htm

The human protein Atlas quotes 67% http://www.proteinatlas.org/humanproteome/brain

 

Hmm what's the best way to exclude proteins not present in the brain? The common origin of Neuroectoderm and possibly neural crest makes it difficult... perhaps proteins of endodermal, yolk sac, or extraembryonic mesoderm origin?

For example, alpha Fetoprotein is produced by the developing world yolk sac and liver.

[CharonY]

Pretty much it can only be done empirically. However, since more are involved in brain functions (and even more if we include development) what would be the benefit of this exercise?

[Xalatan]

The empirical experiment has already been done, these authors may answer your question best.

 

http://science.sciencemag.org/content/347/6220/1260419

The editors at Science seemed to think the exercise was worthwhile enough to publish in their journal.

[CharonY]

No, I meant the exercise you were proposing, trying to find proteins that are not expressed in the brain a priori. The study was used to get a general overview of expression patterns in different tissue, rather than finding tissue specific proteins. The qualitative mapping is something that was done in the last two decades and only had limited use with regard to tissues. More importantly than just presence or absence is the dynamics of expression and how they work together. Note that this is very close to my own research interests and I can go to quite some depth in this area, if necessary.

[Xalatan]

The proteins related to the brain has already been mapped a posteriori. For the sake of forum discussion it's interesting to read the results and reason which proteins are not related, but I wouldn't misinterpret it as "Proposing an exercise to try to find proteins that are not expressed in the brain a priori". If the subject is close to your research interest you can propose your own exercises.

[CharonY]

You misunderstand the research question. It is not about finding what is and what is not in brain tissue (which, BTW is not entirely mapped anyway), as that is simply not very informative. The expression is where the interest is. One of the few other areas where qualitative information could be interesting if a high resolution comparison of different brain tissue.

Of course qualitative studies have been done, but we have not learned much from it. The a posteriori comment was aimed at your earlier post, where you specifically speculated about excluding proteins.

 

Or to put it differently you are free to look at lists of proteins that have not been detected in tissue so far (which n is not the same as not being synthesized), but at this point there is little to learn from it.

[Genecks]

If it's there, it's involved. Simple. EZ. Analogy: Load on electrical circuit.

 

Structure-function is different.http://www.jstor.org/stable/1413176?seq=1#page_scan_tab_contents

Edited March 15, 2016 by Genecks

[Jessica_1995]

Among some geneticists have an idea that what you need already in early childhood to examine the genotype of the child and find out what it is more, and what less capable. And then specifically prepare your child for the appropriate profession.
How do you think this idea should be implemented in life?

[CharonY]

I think you are thinking about a "Brave New World", which luckily is fiction. However, the part that people are seriously thinking about is to look for potential diseases and risk factors and ways to mitigate them.

[Claire]

How did the scientists identify those genes present in the human brain? What are the equipments used?

[CharonY]

All genes are present in (almost) all cells. Many genes are required for basic cellular processes and are expressed in varying degrees in all tissues. An usually somewhat limited set of genes are expressed exclusively or mostly in certain tissues. Monitoring of genes is obviously not useful, but standard mRNA analysis (q-PCR, microarrays, RNA-Seq etc.) are used to monitor transcription, while protein (e.g. Western, ElLISA) or proteome analyses are used to monitor translation.