Wednesday, September 10, 2008

Parkinson’s Disease and Sonic Hedgehog

You read the title of this post correctly! Now you’re asking what the heck do Parkinson’s Disease and Sonic the Hodgehog have in common? Well, the disease and the video game have nothing in common, but a brain protein named after the video game is being linked to the disease. That’s right there is a protein in your brain named Sonic Hedgehog (shh) that is implicated in Parkinson’s Disease. I thought I was reading something wrong when I first read an article about Sonic Hedgehog, but I was not wrong and this was no joke.

There are a group of brain proteins called hedgehogs of which Sonic Hedgehog is one. The role of shh is seen during embryogenesis (embryo growth) and spurs development of dopaminergic neurons in the basal ganglia section of the brain which is affected in PD. The protein is now known to exist in the adult brain too.

The name alone inspired me to learn more about this protein so I began searching the Internet for different articles about this uniquely named molecule. What I found was an entire body of knowledge and study about this “hedgehog” protein. It turns out that there are three separate avenues of study of shh in Parkinson’s.

First, researchers are looking at whether this protein could cause adult stem cells in the brain to differentiate into (become) dopamine producing neurons. Obviously being able to grow more dopaminergic neurons in the affected areas in patients with PD would help tremendously. Researchers are still working on this avenue of study in animals. Time will tell if this has efficacy in humans.

The second avenue of research explores applying shh directly into the basal ganglia. It appears that shh can work as an actual neurotransmitter in the brain and when applied to the basal ganglia in animal studies the amount of electrical activity in the subthalamic nucleus decreased. Since the subthalamic nucleus is hyperactive in PD, a compound that decreases this activity would be a possible treatment. Again, this line of research is being pursued, but human results are not known at this time.

Lastly, several researchers explored the neuroprotective properties of Sonic Hedgehog and also another protein, Gli-1. They delivered both of these compounds to the brain via a genetically engineered virus. What they found was that both of these proteins appear to protect neurons and prevent neuronal loss as compared to other controls. Sonic saves the day!

I started reading about Sonic Hedgehog because I found the name amusing and thought it was great that neuroscientists have a wonderful sense of humor. What I found was 3 different paths of research about this one compound. I am still amazed that researchers can take one particular protein and then can find 3 completely different potential ways that this protein can help in a disease like Parkinson’s. None of these avenues have led to clinical applications yet, but that does not mean that one or all won’t in the future.

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