Mutant gene tied to brain diseases
NEW YORK, Aug 31, 1999 (Reuters Health) -- A gene defect that impairs
cell's ability to ``houseclean'' proteins can lead to degeneration of
brain cells, report Japanese researchers.
The findings are the first to confirm the theory that proteins that
cannot be broken down accumulate in brain cells, leading to
neurodegenerative disorders such as Alzheimer's, Huntington and
PARKINSON'S disease.
Normally, cells mark proteins that are destined to be broken down as
waste, with a protein called ubiquitin. Ubiquitin is subsequently
released from the degraded proteins and recycled for future use.
The team of researchers found that mice with neurodegenerative disorders
have a defective gene, which prevents an enzyme from producing and
recycling ubiquitin. As a result, there is a build-up of waste in nerve
cells, which leads to their degeneration.
``Our data suggest that altered function of the ubiquitin system
directly causes neurodegeneration,'' they write in the September issue
of Nature Genetics.
The team of researchers, led by Kazumasa Saigoh and Yu-Lai Wang of the
National Center of Neurology and Psychiatry in Tokyo, studied a strain
of genetically altered mice called ''gad'' mice whose brains show
changes similar to those of humans with inherited neurodegenerative
diseases. They compared the diseased mouse brains with those of normal
mice, homing in on the enzyme responsible for producing ubiquitin.
The authors write that their findings provide ``a useful model for
investigating human neurodegenerative disorders.''
In an accompanying editorial, Marcy Macdonald of Harvard Medical School
notes that it remains to be seen why the genetic defect affects neurons
specifically.
``This is not an easy challenge,'' she writes. ``Certainly, the
discovery bodes well for our understanding of this complex and essential
cellular pathway in the nervous system.''
SOURCE: Nature Genetics 1999;23:10-11, 47-51.
Copyright © 1996-1999 Reuters Limited.
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Judith Richards, London, Ontario, Canada
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