Expert: Dana Krempels, Ph.D. - 8/14/2007

Question
Hello Dana,

I'm trying to understand the conclusion in the following report :-


http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSear...

Is it saying laughter can help with diabetes via some effect on our genes?  I'm a layman, you might have a better shot at understanding this.  Sorry if this is out of your ambit.  Thanks!
Regards,
Usuff

Answer
Dear Usuff,

Wow, that's a very interesting study!

The results don't mean that laughter is actually changing the DNA sequence, however.  It means only that in the patients in the treatment group, that expression of the genes that affect the activity of a particular protein receptor (located in the plasma membrane of certain cells) changes in response to laughter.

To make sense of this, let me explain about gene expression itself.

When we first come into being as zygotes (fertilized eggs), the nucleus of that zygote contains two copies of our genome:  one from mom, one from dad.  Each gene in that genome encodes the instructions for manufacturing a certain type of protein, often an enzyme.  Enzymes are working proteins that do things such as building other structures in the cell, activating other genes so that they will start making proteins, turning *off* certain genes so that they will stop making protein, etc.  Each enzyme has a very specific job.

As the zygote develops, the enzymes it has made with the instructions in its various genes continue to turn ON some genes (i.e., causing them to be "expressed"), and turning OFF others, sometimes permanently.  In this way, each newly generated cell grown from the original zygote attains its own identity (e.g, as a liver cell, a retinal cell, a kidney cell), with certain genes being expressed, and others being turned off.  If our different cells did not have different genes turned on and off, then they all would be the same as each other, and we'd be great blobs of liver-like tissue blorping along the substrate.  :)

Once the organism is fully developed, genes continue to be turned ON and OFF by enzymes, but now instead of being charged with building the organism, they *run* the organism by controlling metabolism, responding to environmental stimuli, etc.  

For example, after you eat a large meal, certain genes are turned ON to change the amount of a neurotransmitter called serotonin in your bloodstream, and others turn on to change the receptivity of serotonin receptors.  Once attached to the receptor, serotonin sets up a cascade of other reactions that ends up making us feel sleepy.

Pretty much everything we do and feel is, at some level, a result of the activity or inactivity of the genes with which we were born and which allow us to function.

So now, getting back to the diabetes study:  It appears that the environmental stimulus of laughter somehow changes the gene expression controlling a specific cellular receptor to which a protein called prorenin attaches.  Prorenin, as its name implies, is somehow involved in the maintenance of the kidneys (I don't know its specific mode of action).  

If the study's results are correct, then this could mean that laughter may have the overall effect of keeping high levels of prorenin in the system working to protect the kidneys, and hence preventing the kidney damage often seen in diabetes patients.

*whew!*  Sorry for the long explanation, but I hope it made it a little more clear if you haven't yet had a lot of background in genetics.

Please let me know if this wasn't clear, and if I need to explain things a little better.

Hope that helps!

Dana