The process of inducing GFAP aggregates in astrocytoma-derived cells is different between R239C and R416W mutant GFAP. A time-lapse recording study

Alexander disease (ALX) is a rare neurodegenerative disease caused by the gene mutations encoding glial fibrillary acidic protein (GFAP). The formation of aggregates in the cytoplasm of astrocytes, which mainly consists of GFAP, is characteristic of ALX. To examine the dynamic process of aggregates between the different domains of GFAP, we performed time-lapse recording on two different mutant GFAP. R239C and R416W GFAP mutations located in the rod domain and tail domain, respectively, were transfected into astrocytoma-derived cells, and their real-time dynamics were observed using time-lapse recording. Our time-lapse recording study indicated that the process of inducing aggregates would be different between R239C and R416W. In GFP-R239C cells, 32.4% first appeared as aggregates, and clusters of aggregates in the cytoplasm tended to move inward and form amorphous aggregates. On the other hand, 82.0% of GFP-R416W cells first showed disrupted GFAP, with a bubble-like or ring-like structure; however, most cells maintained their structure and were capable of cell division. Our result indicates that the mechanism of GFAP aggregation depends on the domain in which the point mutation is located. A different approach to ALX therapy should be considered according to the domain of GFAP.