Synemin is expressed in reactive astrocytes and Rosenthal fibers in Alexander disease.

[alexander disease]

Alexander disease (AxD ) is a neurodegenerative disorder with prominent white matter degeneration and the presence of Rosenthal fibers containing aggregates of glial fibrillary acidic protein (GFAP ), and small stress proteins HSP 27 and Î±B-crystallin , and widespread reactive gliosis . AxD is caused by mutations in GFAP , the main astrocyte intermediate filament protein . We previously showed that intermediate filament protein synemin is upregulated in reactive astrocytes after neurotrauma . Here , we examined immunohistochemically the presence of synemin in reactive astrocytes and Rosenthal fibers in two patients with AxD . There was an abundance of GFAP -positive Rosenthal fibers and widespread reactive gliosis in the white matter and subpial regions . Many of the GFAP -positive reactive astrocytes were positive for synemin , and synemin was also present in Rosenthal fibers . We show that synemin is expressed in reactive astrocytes in AxD , and is also present in Rosenthal fibers . The potential role of synemin in AxD pathogenesis remains to be investigated .