Scientists have found that a mutation in a single gene can entirely shut down the process by which axons – the parts of the nerve cell that are responsible for sending signals to other cells – regrow themselves after being cut or damaged. “Axons, which form long bundles extending out from nerve cells, ideally survive throughout an animal’s lifetime. To be able to survive, nerve cells need to be resilient and, in the event of injury or simple wear and tear, some can repair damage by growing new axons,” Prof Rolls explained. “The fact that the spastin protein plays a critical role in regeneration is particularly intriguing because, in humans, it is encoded by a disease gene called SPG4,” Prof Rolls said. “When one copy of this gene is disrupted, affected individuals develop hereditary spastic paraplegia (HSP), which is characterized by progressive lower-limb weakness and spasticity as the long-motor axons in the spinal cord degenerate. Thus, identifying a new neuronal function for spastin may help us to understand this disease.”
The team members bred three genetically distinct groups of fruit flies in the laboratory to observe how various spastin gene combinations might affect the behavior of nerve cells after injury. The first group of flies had two normal copies of the gene; the second had one normal copy and one mutant copy; while the third had two mutant copies. Then, in all three groups, the scientists cut the axons of the flies’ nerve cells and observed the regeneration process. The scientists also found that an impaired spastin gene affected only how the axons regrew after being severed. That is, the gene did not seem to play a role in the developmental stage when axons were being assembled for the first time. In addition, the researchers found that, while the gene affected the flies’ axons, their dendrites – the parts of the neuron that receive information from other cells and from the outside world – continued to function and repair themselves normally.
What types of injuries does this gene focus on? Internal or external injuries? In your opinion, do you think that this gene could replace damaged nerve cells in the human brain?
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