Asymmetric localization of prospero and numb specifies cell fates in the Drosophila CNS

A central question in developmental biology is how can two genetically equivalent cells become different? Nowhere is this question more compelling than in the case of sibling cells, where each is derived from the single division of a parental cell. This thesis identifies two proteins involved in generating differences in sibling cells. The numb protein is asymmetrically localized to the cortex of dividing precursor cells in the Drosophila central and peripheral nervous systems. numb is then segregated into only one of the progeny cells where it is necessary and sufficient to autonomously specify that cell's fate. numb functions to specify cell fate by repressing extrinsic cell signalling factors. The prospero protein is also asymmetrically localized to the cortex of dividing precursor cells in the Drosophila central and peripheral nervous system and gut. The prospero protein is then localized to the nucleus of the progeny cell where it regulates gene expression. By regulating gene expression in only one progeny cell, prospero makes the sibling cells different. Correct localization of prospero in the precursor cell requires entry into mitosis and the asymmetric localization of prospero and numb are independent of each other. Thus, numb and prospero are determinants that are asymmetrically localized during cell division to generate differences in sibling cells by unique mechanisms. A gene required for correct prospero expression within a specific glial lineage and the role of prospero in eye development are also examined.U of I OnlyETDs are only available to UIUC Users without author permissio