Rinsho Shinkeigaku (Clinical Neurology)

The 42nd Annual Meeting of the Japanese Society of Neurology

Symposium II-1: Apoptosis of neurodegenerative disorders
Molecular mechanisms of neurodegeneration in@Dentatorubral-pallidoluysian atrophy (DRPLA)

Shoji Tsuji, M. D.

Department of Neurology, Brain Research Institute, Niigata University

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder characterized by various combinations of cerebellar ataxia, choreoathetosis, myoclonus, epilepsy, dementia and psychiatric symptoms. With the discovery of the gene for DRPLA in 1994, molecular mechisms of neurodegeneration has been intensively investigated. Expression of trunctaed DRPLA proteins in cultured cell has been shown to result in aggregate body formation and apoptosis. We have developled transgenic mice for DRPLA (Q129 mice). The Q129 mice showed a severe neurological phenotype characterized by ataxia, myoclonus and seizures. Although numerous neuronal intranuclear inclusions (NIIs) were observed in the brain, obvious neuronal loss was not observed. NIIs, however, appeared much later than the phenotypic presentations, and intranuclear accumulation (diffuse nuclear staining) of mutant proteins was the earliest phenomenon. These results suggest that "neuronal dysfunction", but not "neuronal cell death", is responsible for the phenotypes. Hypothesizing that nuclear proteins interacting with expanded polyglutamine stretches are involved in the pathogenesis, we found that that expanded polyglutamine stretches preferentially bind to TAF130, a cofactor involved in CREB-dependent transcriptional activation, and strongly suppressed CREB-dependent transcriptional activation. Taken together, these findings suggest that the interference of CREB-dependent transcription by expanded polyglutamine stretches is involved in the neuronal dysfunction in polyglutamine diseases.

(CLINICA NEUROL, 41: 1064|1066, 2001)
key words: Dentatorubral-pallidoluysian atrophy, polyglutamine disease, apoptosis, neurodegeneration, spinocerebellar degeneration

(Received: 12-May-01)