In embryonic development, countless cells migrate to the place where they will fulfill their function in later life. How exactly they get to a particular place is only partially understood. Scientists from the University of Bonn have already identified a possible mechanism for brain development.
What conclusions have scientists come to?
In a scientific paper, researchers led by Sandra Bless focused on neural progenitor cells in a mouse model.
Cells develop approximately 10 days after fertilization, mature into nerve cells, and then move to specific areas.
According to the researchers, in the early development of the brain, the same complex cell migration is observed in humans.
A protein called GLI3 is known to be related to early brain organization. In the study, scientists completely turned off GLI3 production in mice. They saw that nerve cell migration was severely impaired in the embryos.
Now, the researchers repeated their experiment only in developing nerve cells. They were surprised: the cells reached their destination without a special protein. Cells do not need GLI3 directly to take their position.
In their further search for protein functions and cell migration mechanisms in a growing brain, researchers came across the neural pathways of peripheral nervous system cells. Although these peripheral nerve cells are located outside the brain, they also form processes that penetrate the brain. They do this not individually, but in the form of whole bundles that are very similar to computer wires.
Scientists from Bonn were now able to show that part of the neurons find their place with the help of special "protein" paths. This only worked on mouse embryos that produced GLI3. However, if they lacked GLI3, neural pathways were much less durable.
Neuroscientists suspect that a decrease in the strength of the nerve pathways leads to a loss of their function. However, what function and mechanisms GLI3 has should be clarified in further studies.
How are vascular and nerve cell growth associated with neurodegenerative disorders?
The blood vessels of the brain not only supply organs with oxygen and nutrients. They also perform contribute to the development of neural networks. For several years, specialists knew that the vascular and nervous systems develop in a similar way.
Researchers have come to the surprising conclusion: "blood vessels and nerve cells participate in brain development together."
The group initially used the development of blood vessels in mice as a validated model to study the effects of various substances. Ultimately, scientists were interested in the connection between blood vessels and neuronal cells.
In studies, they found that the Reelin molecule, which affects the migration of neurons, is also capable of affecting vascular growth. This protein is also activated in the cells of the inner vessels.
Scientists decided to exclude the Reelin signaling cascade from endothelial cells, and then see how this affects the organization of neurons and glial cells in the cerebral cortex. Studies have shown that endothelial cells direct neurons to their correct position in the cerebral cortex.
As a mechanism of action, scientists suggested that vascular cells secrete laminin, which accumulates around the vessels of the brain. They help to properly fix the fibers of glial cells necessary for the proper development of the cerebral cortex.
Scientists have also shown that impaired brain development is caused by abnormal migration of nerve cells.
They simply do not find their place, so they work incorrectly. Some neuropsychiatric and neurodegenerative disorders are associated with abnormal vascular intercourse.
It is important to understand the ways and mechanisms of signaling in this post in order to find new approaches to treating dementia and mental illness. New methods of treating diseases of the central nervous system will be aimed at "correction" of the location of nerve cells.
