Chromosome replication, segregation and transmission are mechanisms used by organisms and cells to ensure the faithful inheritance of essential genetic traits. Errors in chromosome inheritance can result in genomic abnormalities (aneuploidy) that cause a variety of human disorders, including spontaneous abortions, birth defects (e.g. Down's Syndrome) and cancer. The centromere is an essential chromosomal element that is associated with the kinetochore, which serves as the key attachment site to the spindle during mitosis and meiosis. Proper centromere function also requires normal sister-chromatid cohesion and separation. Major gaps exist in our understanding of the composition and regulation of the centromeric DNA and associated proteins in multicellular organisms, despite its importance to cell function and viability. Analyzing the function of centromere proteins in metazoans would be facilitated by taking advantage of the powerful genetic, molecular and cell biological approaches available with Drosophila. The fruit fly provides a viable, tractable intermediate that combines many of the molecular-genetic approaches available in yeasts with the cytological resolution, multicellularity and chromosome structure of mammals. In addition, there is a well-defined, manipulable Drosophila minichromosome (Dp1187) that has been succesfully utilized in the study of higher eukaryotic centromeres. The long term objectives of these studies are to identify the types of proteins involved in centromere (kinetochore and sister chromatid cohesion) functions in metazoans, and to understand their regulation, properties and functions. We will accomplish these goals with the following specific aims: 1) Identify candidate Drosophila centromere protein genes with genetic screens that utilize partially unstable minichromosome derivatives, and molecular searches for Drosophila homologues of yeast and mammalian centromere proteins, and 2) Investigate the function of candidate centromere protein genes and determine their roles in the cell using cell biological, genetic and molecular methodologies. The results of these studies will provide new information about the trans-acting components responsible for inheritance in Drosophila, and will serve as a model system for further investigations in other eukaryotes. Elucidating basic information about centromere components in multicellular eukaryotes has intrinsic interest, but is also likely to have applications to the diagnosis and treatment of aneuploid in human populations.
