AsianScientist (Sep. 6, 2018) – Researchers at Nagoya University, Japan, have identified molecules that allow roundworms to regenerate damaged nerves. They published their findings in Nature Communications.
In humans, damage to the branches of nerves—called axons—can be relatively well repaired should they occur in peripheral regions of the body. However, this repair is less effective in the brain and the spinal cord.
To better understand the fundamental mechanisms of axonal repair, a team of scientists led by Professor Kunihiro Matsumoto at Nagoya University has used the roundworm Caenorhabditis elegans as a model organism. The team used a laser to cut roundworm axons and analyzed the subsequent series of molecular reactions that occurred. They found that this laser-induced damage resulted in the movement of a lipid called phosphatidylserine (PS) from the inside of cells to their outside. The movement of PS was mediated by a protein called an ABC transporter.
PS is better known as an ‘eat me’ signal that triggers neighboring cells to engulf a dying cell. In this case, however, the researchers found that externalized PS triggered a series of reactions that eventually led to the repair of the axon. They noted that the PS labeling appeared only at the severed sites and existed for only a short time (~one hour), which is in contrast to PS labeling in dying cells that remains for a long time until the cells are eliminated.
“We were able to dissect the complex range of molecules involved in axon repair by using fluorescent labels in and around the severed axon, and by knocking down individual components [of specific molecular pathways],” said Matsumoto.
“Although many of these molecules are also active in promoting phagocytosis of apoptotic cells, in axon repair that creates a ‘save me’ signal rather than an ‘eat me’ one, which enables the axons to regenerate.”
Now that the researchers understand how this system works in the relatively simple roundworm, they may be able to decipher how axonal repair takes place in humans. They added that their findings could lead to the discovery of a range of targets for pharmaceutical interventions to treat conditions like brain and spinal cord injuries.
The article can be found at: Hisamoto et al. (2018) Phosphatidylserine Exposure Mediated by Abc Transporter Activates the Integrin Signaling Pathway Promoting Axon Regeneration.
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Source: Nagoya University; Photo: Shutterstock.
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