NACP/alpha-synuclein and tau constitute two distinctive subsets of filaments in the same neuronal inclusions in brains from a family of parkinsonism and dementia with Lewy bodies: double-immunolabeling fluorescence and electron microscopic studies

The co-localization of NACP/alpha-synuclein and tau epitopes was examined i n the brain stem and hippocampal formation in two patients from a family of autosomal dominant parkinsonism and dementia with Lewy bodies (LBs) withou t two reported missense mutations in the NACP gene. Double-labeling immunof luorescence study revealed that some brain stem LBs, cortical LBs, pale bod ies, Lewy-related neurites, and neurofibrillary tangles expressed both NACP epitopes and the PHF tan AT8 epitope. Double-immunolabeling electron micro scopy demonstrated that the NACP antibody selectively labeled 9- to 13-nm-t hick straight filaments (LB filaments), whereas AT8 recognized twisted tubu les with 80-to 100-nm-interval constrictions in the same neuronal inclusion s. We show that NACP and tau aggregate into different filamentous component s even if both proteins are incorporated into the same inclusions.