A team of IRCM researchers, led by Dr. Fr-d-ric Charron, recently uncovered a nerve cell's internal clock, used during embryonic development. The discovery was made in collaboration with Dr. Alyson Fournier's laboratory at the Montreal Neurological Institute. Published today in the prestigious scientific journal Neuron, this breakthrough could lead to the development of new tools to repair and regenerate nerve cells following injuries to the central nervous system.
Researchers in Dr. Charron's laboratory study neurons, which are the nerve cells that make up the central nervous system (brain and spinal cord). They want to better understand how neurons navigate through the developing embryo to arrive at their correct destination.
"To properly form neural circuits, developing axons (long extensions of neurons that form nerves) follow external signals to reach the right targets," says Dr. Fr-d-ric Charron, Director of the Molecular Biology of Neural Development research unit at the IRCM. "We discovered that nerve cells also have an internal clock, which changes their response to external signals as they develop over time."
For this research project, IRCM scientists focused on the Sonic Hedgehog (Shh) protein, which gives cells important information for the embryo to develop properly and plays a critical role in the development of the central nervous system.
"It is known that axons follow the Shh signal during their development," explains Dr. Patricia Yam, research associate in Dr. Charron's laboratory and first author of the study. "However, axons change their behaviour once they reach this protein, and this has been a mystery for the scientific community. We found that a nerve cell's internal clock switches its response to external signals when it reaches the Shh protein, at which time it becomes repelled by the Shh signal rather than following it."