Milestone in the regeneration of brain cells
The majority of cells in the human brain are not nerve cells but star-shaped glia
cells, the so called "astroglia". "Glia means "glue", explains
Götz. "As befits their name, until now these cells have been regarded merely
as a kind of "putty" keeping the nerve cells together.
A couple of years ago, the research group had been already able to prove that these
glia cells function as stem cells during development. This means that they are able
to differentiate into functional nerve cells. However, this ability gets lost in
later phases of development, so that even after an injury to the adult brain glial
cells are unable to generate any more nerve cells.
In order to be able to reverse this development, the team studied what molecular
switches are essential for the creation of nerve cells from glial cells during development.
These regulator proteins are introduced into glial cells from the postnatal brain,
which indeed respond by switching on the expression of neuronal proteins.
In his current work, Dr. Benedikt Berninger, was now able to show that single regulator
proteins are quite sufficient to generate new functional nerve cells from glia cells.
The transition from glia-to-neuron could be followed live at a time-lapse microscope.
It was shown that glia cells need some days for the reprogramming until they take
the normal shape of a nerve cell. "These new nerve cells then have also the
typical electrical properties of normal nerve cells", emphasises Berninger.
"We could show this by means of electrical recordings".
"Our results are very encouraging, because the generation of correctly functional
nerve cells from postnatal glia cells is an important step on the way to be able
to replace functional nerve cells also after injuries in the brain," underlines
Magdalena Götz.
Source: National Research Center for Environment and Health
http://www.physorg.com/news106834352.html
Researchers identify key mechanism that regulates the development of stem
cells into neurons
Researchers at the University of Southern California (USC) have identified a novel
mechanism in the regulation and differentiation of neural stem cells.
Researchers found that the protein receptor Ryk has a key role in the differentiation
of neural stem cells, and demonstrated a signaling mechanism that regulates neuronal
differentiation as stem cells begin to grow into neurons. The study will be published
in the Nov. 11 issue of the journal Developmental Cell, and is now available online.
The findings could have important implications for regenerative medicine and cancer
therapies, says Wange Lu, Ph.D., assistant professor of biochemistry and molecular
biology at the Keck School of Medicine of USC, and the principal investigator on
the study.
"Neural stem cells can potentially be used for cell-replacement therapy for
neurodegenerative diseases such as Alzheimer's and Parkinson's Disease,
as well as spinal cord injury," Lu says. "Knowledge gained from this study
will potentially help to generate neurons for such therapy. This knowledge
can also be used to inhibit the growth of brain cancer stem cells."
During brain development, neural stem cells respond to the surrounding environment
by either proliferation or differentiation, but the molecular mechanisms underlying
the development of neural stem cells and neurons are unclear, Lu notes.
Ryk functions as a receptor of Wnt proteins required for cell-fate determination,
axon guidance and neurite outgrowth in organisms. Researchers at the Eli and Edythe
Broad Center for Regenerative Medicine and Stem Cell Research at USC analyzed sections
of the forebrain in animal model embryos to investigate Ryk's function in vivo.
They found that during neurogenesis, when neural stem cells start to grow into neurons,
Ryk protein is cleaved and translocates to the cell nucleus to regulate neuronal
differentiation.
This finding is extremely important for understanding the regulation of self-renewal
and differentiation of neural stem cells, Lu says. Previous research has shown that
Ryk functions as a receptor of Wnt proteins. However, the role of Ryk in neural
stem cells and the molecular mechanism of Ryk signaling have not previously been
known.
"This study will help in our efforts to produce nerve cells from embryonic
stem cells, and may lead to the development of new strategies for the repair of
the nervous system, using protein or small molecule therapeutic agents," says
Martin Pera, Ph.D., director of the Eli and Edythe Broad Center for Regenerative
Medicine and Stem Cell Research at USC.
Further research is needed to explore how Ryk regulates neuronal gene expression,
Lu says. Researchers are now expanding their research to studies of differentiation
of human embryonic stem cells into neural stem cells and neurons. These studies
are very important for regenerative medicine and drug discovery for therapy of
neurodegenerative diseases.
Source: University of Southern California
http://www.physorg.com/news145539812.html