Increases in fragmented glial fibrillary acidic protein levels in the spinal cords of patients with amyotrophic lateral sclerosis

Using one-dimensional polyacrylamide gel electrophoresis, we analyzed protein fractions extracted from the spinal cords of patients with amyotrophic lateral sclerosis (ALS). Several protein bands with molecular weights of 35-55 kDa were stained with Coomassie brilliant blue much more intensely in the ALS than in the non-ALS spinal cord. Glial fibrillary acidic protein (GFAP) immunoreactivity showed a significant decrease of 50 and 45 kDa band and increase in fragmented 36 and 37 kDa bands, which represented GFAP fragments devoid of 59 and 40 residues from the N-terminal, respectively, as determined by protein sequence analysis. Immunohistochemical examination of ALS spinal cord transections demonstrated increased GFAP-stained astrocytes in the shrunken ventral horn with massive degeneration of motoneurons. These results will provide new insight into the possible role of astrocytes in the pathophysiology and/or pathogenesis of ALS.