Intermediate filament protein partnership in astrocytes

Intermediate filaments are general constituents of the cytoskeleton. The fu nction of these structures and the requirement for different types of inter mediate filament proteins by individual cells are only partly understood. H ere we have addressed the role of specific intermediate filament protein pa rtnerships in the formation of intermediate filaments in astrocytes. Astroc ytes may express three types of intermediate filament proteins: glial fibri llary acidic protein (GFAP), vimentin, and nestin. me used mice with target ed mutations in the GFAP or vimentin genes, or both, to study the impact of loss of either or both of these proteins on intermediate filament formatio n in cultured astrocytes and in normal or reactive astrocytes in vivo. We r eport that nestin cannot form intermediate filaments on its own, that vimen tin may form intermediate filaments with either nestin or GFAP as obligator y partners, and that GFAP is the only intermediate filament protein of the three that may form filaments on its own. However, such filaments show abno rmal organization. Aberrant intermediate filament formation is linked to di seases affecting epithelial, neuronal, and muscle cells. Here we present mo dels by which the normal and pathogenic functions of intermediate filaments may be elucidated in astrocytes.