Lissencephaly gene product. Localization in the central nervous system and loss of immunoreactivity in Miller-Dieker syndrome.

The Miller-Dieker syndrome, a disorder of neuronal migration, is caused by deletions of chromosome 17p13.3. Recently, a gene on 17p13.3, named LIS-1, was identified as the causative gene for this cerebral anomaly. Here we immunochemically and immunohistochemically localized the gene product, LIS-1 protein, among control normal subjects and patients with Miller-Dieker syndrome, using specific antibodies raised against synthetic peptide fragments of LIS-1 protein. Western blot analyses identified LIS-1 protein as a 45-kd, heparin-binding protein abundant in the cytosolic fraction. The protein was restricted to the central nervous system and detectable in brains of controls of all ages, from the early fetal to adult period. Immunostaining demonstrated the widespread distribution of LIS-1 protein in the brain and spinal cord of controls and a loss of immunoreactivity in individuals with Miller-Dieker syndrome. These results are consistent with the notion that a deficiency of LIS-1 protein is the direct cause of the brain malformation and that the protein plays a critical role in neuronal migration.