ScienceDaily (Jun. 4, 2008) — A new
study at the Montreal Neurological Institute at McGill University
identifies a key mechanism for the normal development of
Motor nerve
cells (motor neurons) - cells that control muscles. This finding is
crucial to understanding and treating a range of conditions involving
nerve cell loss or damage, from spinal cord injury to neurodegenerative
diseases such as ALS, also known as Lou Gehrig’s disease.
Nerve cell Regeneration is a complex process. Not
only do nerve cells have to regenerate, but just as importantly, their
specific and individual connections need to be regenerated also. The
study, published recently in the Proceedings of the National Academy of
Sciences, provides invaluable insight into these vital processes by
understanding the mechanisms involved in normal development of selected
types of spinal cord motor nerve cells.
Motor neurons are highly specialized. They have distinct
characteristics and connect to specific muscle types in specific
regions of the body. “These highly targeted nerve cell-to-muscle
connections are determined in part by specific patterns of gene
expression during embryonic development. More specifically, certain
genes are expressed which tell the Neuron what its properties will be,
where to settle and which particular muscle to connect with,”
says Dr. Stefano Stifani, neuroscientist at the Montreal Neurological
Institute and lead investigator in the study.
When nerve cells develop they require characteristic patterns of
gene expression in order to become motor neurons or another type of
nerve cell called interneurons. Dr. Stifani and colleagues show that
during development, motor nerve cells have to express certain genes
that continually suppress interneuron developmental characteristics.
“We have identified a key factor, called Runx1, which controls
the correct development of motor neurons in the upper part of the
spinal cord. Runx1, a factor that controls gene expression, helps motor
neurons to maintain their status by regulating the expression of
specific genes. In doing so, it might also help motor neurons find
their target muscles.”
Understanding the normal development and the highly specialized
nature of nerve cells has important implications for understanding
diseased or damaged nerve cells. For example, in ALS, the motor nerve
cells that are involved in swallowing and controlling the tongue are
often the first to degenerate. Knowing the specific patterns of gene
expression of different motor nerve cells may help to explain why
certain motor neurons are more susceptible to degeneration and help
identify new targets for treatments.
It was funded by the Neuromuscular Research Partnership, an
initiative of ALS Canada, Muscular Dystrophy Canada, and the Canadian
Institutes of Health Research.
Journal reference:
- Stifani et al. Suppression of interneuron programs and maintenance of selected spinal motor neuron fates by the transcription factor AML1/Runx1. Proceedings of the National Academy of Sciences, 2008; 105 (17): 6451 [link]
