Transgenic (Tg) mice overexpressing human wild-type alpha-synuclein in oligodendrocytes under the control of the 2,' 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter are shown here to recapitulate features of multiple system atrophy (MSA), including the accumulation of filamentous human alpha-synuclein aggregates in oligodendrocytes linked to their degeneration and autophagocytosis of myelin. Significantly, endogenous mouse alpha-synuclein also accumulated in normal and degenerating axons and axon terminals in association with oligodendroglia and neuron loss and slowly progressive motor impairments. Our studies demonstrate that overexpression of alpha-synuclein in oligodendrocytes of mice results in MSA-like degeneration in the CNS and that alpha-synuclein inclusions in oligodendrocytes participate in the degeneration of neurons in MSA.

Heat shock proteins (Hsps) facilitate refolding of denatured polypeptides, but there is limited understanding about their roles in neurodegenerative diseases characterized by misfolded proteins. Because Parkinson's disease (PD), dementia with Lewy bodies, and multiple system atrophy are ␣-synucleinopathies characterized by filamentous ␣-synuclein (␣-syn) inclusions, we assessed which Hsps might be implicated in these disorders by examining human brain samples, transgenic mouse models, and cell culture systems. Light and electron microscopic multiple-label immunohistochemistry showed Hsp90 was the predominant Hsp examined that co-localized with ␣-syn in Lewy bodies, Lewy neurites, and glial cell inclusions and that Hsp90 co-localized with ␣-syn filaments of Lewy bodies in PD. Hsp90 levels were most predominantly increased in PD brains, which correlated with increased levels of insoluble ␣-syn. These alterations in Hsp90 were recapitulated in a transgenic mouse model of PD-like ␣-syn pathologies. Cell culture studies also revealed that ␣-syn co-immunoprecipitated preferentially with Hsp90 and Hsc70 relative to other Hsps, and exposure of cells to proteasome inhibitors resulted in increased levels of Hsp90. These data implicate predominantly Hsp90 in the formation of ␣-syn inclusions in PD and related

Dentatorubral-pallidoluysian atrophy (DRPLA) is associated with the expansion of an unstable CAG repeat. Using antibodies against a synthetic peptide corresponding to the sequence of the DRPLA gene product C terminus, we have identified the DRPLA gene product in normal human brains as a approximately 190 kD protein. We also find a larger approximately 205 kD protein specifically in DRPLA brains. Immunohistochemically, the DRPLA gene product is observed mainly in the neuronal cytoplasm. Our results demonstrate the existence of the expanded CAG repeat gene product and support the possibility that the expanded CAG-encoded polyglutamine stretch may participate in the pathological process of the similar trinucleotide repeat diseases.

The brains of 10 Japanese patients with adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) encompassing hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD) and eight Japanese patients with Nasu-Hakola disease (N-HD) and five age-matched Japanese controls were examined neuropathologically with special reference to lesion staging and dynamic changes of microglial subsets. In both diseases, the pathognomonic neuropathological features included spherically swollen axons (spheroids and globules), axon loss and changes of microglia in the white matter. In ALSP, four lesion stages based on the degree of axon loss were discernible: Stage I, patchy axon loss in the cerebral white matter without atrophy; Stage II, large patchy areas of axon loss with slight atrophy of the cerebral white matter and slight dilatation of the lateral ventricles; Stage III, extensive axon loss in the cerebral white matter and dilatation of the lateral and third ventricles without remarkable axon loss in the brainstem and cerebellum; Stage IV, devastated cerebral white matter with marked dilatation of the ventricles and axon loss in the brainstem and/or cerebellum. Internal capsule and pontine base were relatively well preserved in the N-HD, even at Stage IV, and the swollen axons were larger with a higher density in the ALSP. Microglial cells immunopositive for CD68, CD163 or CD204 were far more obvious in ALSP, than in N-HD, and the shape and density of the cells changed in each stage. With progression of the stage, clinical symptoms became worse to apathetic state, and epilepsy was frequently observed in patients at Stages III and IV in both diseases. From these findings, it is concluded that (i) shape, density and subsets of microglia change dynamically along the passage of stages and (ii) increase of IBA-1-, CD68-, CD163- and CD204-immunopositive cells precedes loss of axons in ALSP.