Abstract
Alexander disease (AxD) is a primary genetic disorder of astrocytes caused by heterozygous mutations in GFAP, which encodes the major astrocyte intermediate filament protein, glial fibrillary acidic protein (GFAP). The mechanism of GFAP mutation causing the AxD remains unclear. The aim of this study is to investigate the effect of the novel AxD-causing mutation on GFAP filament formation and stability by using filament assembly in vitro and transient transfection in cultured cells. The results showed that all the GFAP mutations perturbed the filament assembly in vitro and in transiently transfected cells. The E312X GFAP caused the most dramatic effects on filament assembly both in vitro and in transiently transfected cells. This truncated mutant caused extensive filament aggregation coinciding with the activation of caspases, cleavage of GFAP, and a significant decrease in cell viability. These data provide a direct link of GFAP mutation on filament aggregation and loss of cell viability through the activation of caspases and cleavage of GFAP, suggesting that these could be contributing factors in the development of Alexander disease.