Fukutin expression in glial cells and neurons: implication in the brain lesions of Fukuyama congenital muscular dystrophy.

Expression and localization of fukutin, a gene responsible for Fukuyama congenital muscular dystrophy (FCMD), was studied in the central nervous system by in situ hybridization and immunohistochemistry. In control cases, glial cells expressed fukutin and the expression continued from fetuses to adults. Double immunostaining revealed that some of these cells were astrocytes. The glia limitans was stained by immunohistochemistry. In contrast, neuronal expression was decreased with neuronal maturation. The glia limitans formed by endfeet of astrocytes is abnormal in the brain of fetal to adult FCMD cases. These findings suggest an important role of astrocytes for the genesis of FCMD brain, although immature neurons expressed fukutin. In FCMD cases, expression of fukutin looked decreased. In the brain of fetal FCMD cases, decreased expression of fukutin is considered to provoke the disruption of glia limitans. In post-natal FCMD cases, prominent superficial gliosis is observed in the cerebral surface, where fukutin was weakly positive. Reactive increase of astrocytes may be required to maintain the glia limitans for compensating the decrease of fukutin expression in individual astrocytes. In the cerebellum, Bergmann glia, which did not express fukutin in control cases, elongated their cytoplasmic processes to the surface to form glia limitans even in the polymicrogyric area.