MRC National Institute for Medical Research, London
Science for Health
This project is now closed
Manipulating kinetochore function with synthetic physical interactions
Project supervisor: Peter Thorpe (Stem Cell Biology and Developmental Genetics)
During cell division newly duplicated chromosomes must be segregated correctly to daughter cells to ensure that each cell receives the correct complement of genetic material. Any defects in this process results in aneuploidy, cells inheriting an incorrect number of chromosomes, which is a hallmark of cancer cells and the underlying cause of specific birth defects. A carefully choreographed series of molecular events works to achieve accurate chromosome segregation; involving specific proteins being in the right place at the right time. We focus primarily upon proteins of the kinetochore, a large multi-protein complex that attaches chromosomes to the mitotic spindle.
We have developed a novel system to artificially direct proteins to different locations within the cell. This approach is easily assayed on a genome wide scale, allowing us to recruit all proteins to a given cellular location. The system employs an antibody that binds to GFP together with a genome-wide collection of yeast GFP-tagged genes.
Strains in which the forced interaction produces a growth defect are defined as having a “synthetic physical interaction” or SPI. We use SPIs as a way to identify protein interactions that disrupt normal chromosome segregation and can potentially lead to aneuploidy. Many of these SPIs identify regulators – proteins that normally help to control accurate cell division. In this way we are using SPIs to identify novel molecular pathways that regulate and disrupt chromosome segregation.
Additionally, the SPI system offers the chance to artificially move proteins to new locations within the cell. Asymmetric division of the proteins that regulate chromosome segregation is a key feature of adult stem cell homeostasis. We can use SPIs to create conditional protein asymmetry within cells, thus we can determine the effects of asymmetrically distributing kinetochore and other spindle proteins.
The two aims of this project are to:
- Define the SPI partners of kinetochore proteins. Thus we will identify proteins that are capable of regulating accurate chromosome segregation and cell division.
- Use SPI’s to create and disrupt asymmetric mitotic spindles. The effects of a ‘stem cell like’ asymmetric spindle upon chromosome segregation and daughter fate will then be assessed.
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