Tim Stearns
Academic Appointments
- Professor, Biology (School of Humanities and Sciences)
- Professor, Genetics
- Member, Bio-X
Contact Information
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Academic Offices
Personal Information Email Tel (650) 725-6934Administrative Contact Tammy Learned Administrative Assistant Email Tel Work (650) 725-4845
Professional Snapshot
Postdoctoral Advisees
Graduate & Fellowship Program Affiliations
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Scientific Focus
Research Interests
We study the organization and regulation of the microtubule cytoskeleton, and the relationship between the cell cycle and the cytoskeleton. Microtubules are polymers assembled from alpha-tubulin and beta-tubulin subunits, and are an essential element of the cytoskeleton. Microtubules are polar polymers, acting as directional tracks for the many motor proteins that move along them. Microtubules and motors move vesicles and organelles, and make up the spindle, which segregates chromosomes in mitosis and meiosis. One of the keys to microtubule organization is the centrosome, a unique organelle that nucleates microtubule polymerization from free subunits. Remarkably, the centrosome also appears to be a site for integration of cellular signals, and is required for cell cycle progression.
There are four main projects in the lab:
1) Regulation and mechanism of centrosome duplication. We have shown that duplication of the centrosome, the microtubule organizing center of animal cells, is dependent on the cell cycle kinase Cdk2, and on cell cycle-specific proteolysis. We are now working to determine the molecular mechanisms of centrosome duplication and to understand how centrosome duplication is controlled so that it happens once and only once per cell cycle. Cancer cells often have aberrant centrosome numbers, and we are investigating the relationship between aberrant centrosome number and the generation of cells with abnormal, or aneuploid, numbers of chromosomes.
2) Cell cycle control. The cell cycle of all eukaryotes is controlled by cyclin-dependent kinases, or cdks. Animal cells typically have several cdks involved in the complicated choreography of cell cycle control, but yeast cells have only a single cdk, Cdc28p, that drives all cell cycle events, including centrosome duplication. With the goal of identifying the downstream effectors of this important kinase, we are working to find all genes in the yeast genome that when deleted result in...
Publications
- Polo kinase and separase regulate the mitotic licensing of centriole duplication in human cells. Dev Cell. 2009; (3): 344-54
- Centriole age underlies asynchronous primary cilium growth in Mammalian cells. Curr Biol. 2009; (17): 1498-502
- Stem cells: A fateful age gap. Nature. 2009; (7266): 891-2
- Plk1-dependent recruitment of gamma-tubulin complexes to mitotic centrosomes involves multiple PCM components. PLoS One. 2009; (6): e5976
- Primary cilia: cellular sensors for the skeleton. Anat Rec (Hoboken). 2008; (9): 1074-8
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