VESICLES INFLUENCE FUNCTION OF NERVE CELLS
Tiny vesicles
containing protective substances which they transmit to nerve cells apparently
play an important role in the functioning of neurons. As cell biologists at
Johannes Gutenberg University Mainz (JGU) have discovered, nerve cells can
enlist the aid of mini-vesicles of neighboring glial cells to defend themselves
against stress and other potentially detrimental factors. These vesicles,
called exosomes, appear to stimulate the neurons on various levels: they
influence electrical stimulus conduction, biochemical signal transfer, and gene
regulation. Exosomes are thus multifunctional signal emitters that can have a
significant effect in the brain.
The researchers in Mainz already
observed in a previous study that oligodendrocytes release exosomes on exposure
to neuronal stimuli. These exosomes are absorbed by the neurons and improve
neuronal stress tolerance. Oligodendrocytes are a type of glial cell and they
form an insulating myelin sheath around the axons of neurons. The exosomes
transport protective proteins such as heat shock proteins, glycolytic enzymes,
and enzymes that reduce oxidative stress from one cell type to another, but
also transmit genetic information in the form of ribonucleic acids.
"As we have now discovered in
cell cultures, exosomes seem to have a whole range of functions,"
explained Dr. Eva-Maria Krämer-Albers. By means of their transmission activity,
the small bubbles that are the vesicles not only promote electrical activity in
the nerve cells, but also influence them on the biochemical and gene regulatory
level. "The extent of activities of the exosomes is impressive,"
added Krämer-Albers. The researchers hope that the understanding of these
processes will contribute to the development of new strategies for the
treatment of neuronal diseases. Their next aim is to uncover how vesicles
actually function in the brains of living organisms.
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