Researchers have discovered a previously unknown form of cellular communication in the brain in which proteins are directly transferred between neurons. According to them, if we take control of it, we could potentially develop new treatments for dementia and other neurological diseases.
In general, neural communication occurs through the mediation of neurotransmitters scattered across synapses (thus they transmit signals from one cell to another). However, scientists have noticed that certain proteins in the brain move in a different way. This led them to suggest that neurons may also be involved in the exchange of these mixtures.
For example, proteins including tau and synuclein move between brain cells and accumulate in plaques, which contributes to the development of Alzheimer’s disease and other neurodegenerative diseases. Until now, however, researchers were unsure whether this trans-neuronal transfer of proteins represented a purely pathological mode of communication or whether the same mechanism was observed in healthy brain activity.
To answer this question, the study authors used a marker molecule called biotin to label neuronal proteins in the eyes of rats. 11 days later, they found that biotin could be detected in neurons in the animals’ visual cortex. This means that some of the labeled proteins were actually transported to distant cells in the brain.
“This is a completely new way in which cells in the brain can communicate with each other that has never before been integrated into the way we think about health and disease,” said Dr. Hollins Klin, one of the study’s authors.
Using a technique called mass spectroscopy, the researchers identified approximately 200 tagged proteins that reached the visual cortex. Tau and synuclein are among them. This means that the neural transfer of these two mixtures is not limited solely to pathological conditions.
“This confirms that in healthy brains with tau and synuclein, everything is fine and their movement around the brain is normal,” says Klein. “But in people with Alzheimer’s, a toxic form of the protein is transported between neurons.”
A deeper analysis revealed that the proteins are transported from one neuron to another within membrane-bound packages called exosomes, which mediate cellular communication by transporting an array of mediator compounds between cells. The researchers also found that the proteins were normally transferred to excitatory but not inhibitory neurons.
The authors summarize that their findings “demonstrate the non-pathological transport of various endogenous proteins [between neurons]”. According to them, it is quite possible to establish control over this communication and manipulate brain activity. Of course, a lot more research will have to be done before that. However, the results of the present study open up an entirely new avenue for the study and treatment of neurological disorders.
The study is published in Cell Reports.
Source: IFLScience
Photo: nobeastsofierce / Shutterstock
