[Editor’s note: Thomas Jessell, the study’s co-author, co-directs Columbia University’s Zuckerman Institute as a professor of biochemistry and molecular biophysics.]
A study published [February 2017] looks at the genes that are switched on and off in an embryo to wire up fingers and toes to the central nervous system. The molecular-scale view provided in this latest study suggests how the wiring process may have evolved.
What does this tell us about how fine-motor control evolved?
All motor neurons work in the same way. But how do they choose to project to the extremities, where you find the digit muscles? Our findings tell us that two things have to happen: One is that Hox genes must be altered by evolution to get this strange variant code. The other is that you have to avoid retinoic acid if you want to have a chance of being a motor neuron that innervates digit muscles.
Do your findings have any therapeutic potential?
They’re relevant in the context of treating diseases like ALS, a motor neuron degenerative disease that starts with weakness in the extremities and eventually leads to complete loss of all motor function. Until now researchers trying to develop treatments wouldn’t have known how to generate the motor neurons that innervate the limb digit muscles, but our findings give them an opportunity to do so.
[The study can be found here.]
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