Roles of Lissencephaly Gene, LIS1, in Regulating Cytoplasmic Dynein Functions: a Dissertation

Spontaneous mutations in the human LIS 1 gene are responsible for Type I lissencephaly (" smooth brain ). The distribution of neurons within the cerebral cortex of lissencephalic children appears randomized, probably owing to a defect in neuronal migration during early development. LIS 1 has been implicated in the dynein pathway by genetic analyses in fungi. We previously reported that the vertebrate LIS 1 co-localized with dynein at prometaphase kinetochores , and interference with LIS 1 function at kinetochore caused misalignment of chromosomes onto the metaphase plate. This leads to a hypothesis that LIS 1 might regulate kinetochore protein targeting. In order to test this hypothesis , I created dominant inhibitory constrcts of LIS 1. . After removal of the endogenous LIS 1 from the kinetochore by overexpression of the N-termnal self-association domain of LIS 1, dynein and dynactin remained at the kinetochores. This result indicated that LIS 1 is not required for dynein to localize at the kinetochore. Next, CLIP-170 was displaced from the kinetochores in the LIS 1 full-length and the C-termnal WD-repeat overexpressers suggesting a role for LIS 1 in targeting CLIP170 onto kinetochores. LIS 1 was co-immunoprecipitated with dynein and dynactin. Its association with kinetochores was mediated by dynein and dynactin , suggesting LIS 1 might interact directly with subunits of dynein and/or dynactin complexes. I found that LIS 1 interacted