Existence of new neuron repair pathway discovered
Most of your neurons can’t be replaced.
Other parts of your body – such as skin and bone – can be replaced by the body growing new cells, but when you injure your neurons, you can’t just grow new ones; instead, the existing cells have to repair themselves.
In the case of axon injury, the neuron is able to repair or sometimes even fully regenerate its axon. But neurons have two sides – the axon (which sends signals to other cells) and the dendrite (which receives signals from other cells).
Melissa Rolls, an associate professor of biochemistry and molecular biology at Penn State and director of the Huck Institutes’ Center for Cellular Dynamics, has done extensive comparisons of axons and dendrites – culminating recently in a paper published in Cell Reports.
“We know that the axon side can repair itself,” says Rolls, “and we know a bunch of the molecular players. But we really didn’t know whether neurons have the same capacity to regenerate their dendrites, and so that’s what we set out to find in this study.”
“Our lab uses a Drosophila model system, where the dendrites are very accessible to manipulation,” she says, “so we decided that we would start by removing all the dendrites from the neurons to see if they could regenerate. We didn’t start with anything subtle, like taking off just a few dendrites. We said ‘Let’s just push the system to its maximum and see if this is even possible.’ And we were surprised because we found that not only is it possible, it’s actually much faster than axon regeneration: at least in the cells that we’re using, axon regeneration takes a day or two to initiate, while dendrite regeneration typically initiates within four to six hours and it works really well. All the cells where we removed the dendrites grew new dendrites – none of them died; so it’s clear that these cells have a way to both detect dendrite injury and initiate regrowth of the injured part.”
