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Researchers find a cause of ALS, raising hopes for new treatments
A Japanese research team has discovered a cause of amyotrophic lateral sclerosis (ALS), a progressive, terminal disease that gradually weakens muscles throughout the body.
The researchers found that when a gene that maintains protein quality stops functioning, motor neurons become damaged, leading to familial ALS—a form of the disease that runs in families.
The discovery by the joint team, led by associate professor Toru Yamashita and professor Hiroyuki Ishiura from the Medical School at Okayama University, raises hopes for the development of new treatments.
The results of their study were published on July 1 in the international scientific journal Acta Neuropathologica.
ALS is a rare disease in which the motor neurons responsible for controlling muscle movement degenerate and decrease. As signals from the brain telling the body to move fail to reach the muscles, muscles begin to atrophy, eventually impairing even breathing.
In Japan, it is estimated that there are more than 10,000 ALS patients.
About 10 percent of these patients also have a family history of the disease, classified as familial ALS.
The research team analyzed the genes of three patients with familial ALS.
All three were found to have mutations in a gene known as DNAJC7. The functions of this gene are to repair damaged proteins and to prevent abnormal proteins from accumulating.
Previous studies have confirmed that many ALS cases involve abnormal accumulation of a protein called TDP-43 in the cytoplasm of neurons in the cerebral cortex. The patients in this study were also found to have TDP-43 accumulations.
Further experiments using cultured cells confirmed that when DNAJC7 does not function properly, abnormal aggregation of TDP-43 increases—while enhancing the function of DNAJC7 reduced the accumulation of TDP-43.
'We have now discovered that when the DNAJC7 gene does not function correctly, the abnormal aggregation of TDP-43 increases, leading to familial ALS,' Yamashita said. 'Because boosting the functions of DNAJC7 reduced the aggregation, our findings could lead to future treatments.'
