Rotation Projects

General Goals
The programmatic goal of our research is to understand mechanisms that cause genome instability. In humans, genome instability contributes to the incidence of birth defects and spontaneous abortion and is a key factor in the etiology of cancer. In more specific terms, we work on cell cycle checkpoint controls, sister chromatid cohesion, chromosome dynamics and ubiquitin-dependent proteolysis. Each of these related areas are critical for the maintenance of a stable genome. We use yeast as a model system to rapidly discover new concepts that can then be translated to the human system.
 
Yeast Genetic Screens
Interested in performing genetic screens? We are using various screening techniques to isolate novel mutants and to identify new links between cell cycle components. Several approaches are geared at identifying S-phase checkpoint genes. Another approach combines genetics with fluorescence microscopy of living cells to find new proteins required for chromosome dynamics and structure.
 
Cell Cycle Experiments
A classic approach to understanding cell cycle controls involves performing experiments with cultures of synchronized cells. For example, to understand S-phase checkpoint control, we synchronize cells in G1 then follow cycle progression in the presence of DNA replication inhibitors. Such experiments typically involve fluorescence microscopy and FACS analysis to measure cell cycle position. (More Details!)
 
Mammalian Cell Studies
Although mammalian cells are less amenable to genetic studies, they are idea for studying the cell cycle by microscopy. We are using fluorescently tagged proteins and conventional or video microscopy to watch the cell cycle in vivo. Our proteins of interest are depleted from the cells using RNAi technology. (More Details!)
 
Proteins of Interest
Mec1: The yeast homolog of human ATR/ATM. ATM is mutated in ataxia telangiectasia patients that have neurological defects and are cancer-prone  
Rad53: Yeast homolog of human CHK2, a cell cycle checkpoint kinase  
Cdc20: In yeast and humans, Cdc20 is an APC (anaphase promoting complex) specificity factor that directs ubiquitin-dependent degradation of cell cycle proteins  
Pds1: The yeast homolog of human securin, a class of proteins that inhibit anaphase in response to checkpoint controls signals. Securin prevents loss of cohesion between sister DNA duplexes  
Esp1: Yeast version of human separase, the enzyme that cleaves the cohesion molecules that hold sister DNA duplexes together before anaphase of mitosis  
Rad23: In yeast and humans, Rad23 is involved in nucleotide excision repair of, for example, UV-induced DNA damage. Humans with Rad23 mutations are skin cancer-prone  
Top2: Yeast homolog of human DNA topoisomerase II. This enzyme resolves catenations between sister DNA duplexes and is therefore essential for chromosome segregation. It is also a key structural element of chromosomes and is important for chromosome condensation in mitosis  

 

 


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