| Research Abstract |
In this study, we tried to clarify the function of RecQ family helicases to understand the genomic instability resulting in predisposition to cancer and premature aging due to the defect in RecQ family helicases, and obtained following results by using budding yeasts and chicken DT40 cells, which are easily applicable to genetic analysis, as well as cultured human cells.
1. It has been indicated by generating and analyzing BLM-/- and BLM-/-/RAD54-/- DT40 cells that the majority of increased SCEs in BLM disrupted cells are formed via homologous recombination and BLM functions to decrease the formation of DNA double strand breaks during DNA replication.
2. Werner syndrome gene product, WRN, interacted with Ubc9 and SUMO-1 and was actually conjugated with SUMO-1.
3. A novel Werner helicase interacting protein, WHIP, which we found, was co-localized with WRN in the nuclei, and the interaction of these proteins required ATP, indicating a dynamic interaction of these proteins.
4. The genetic analyzes using yeast mutants that overexpression of WHIP in mutants of DNA polymerase δ, RFC, or PCNA resulted in the lethality of the cells indicated the existence of functional relationship between WHIP and DNA polymerase δ, RFC, and PCNA. In addition, physical interaction between WHIP and DNA polymerase δ was indicated by the yeast-two hybrid system.
5. Analyzes using yeasts also indicated the genetical interaction of the yeast BLM/WRN homologue, Sgs1 with Mre11, Sld3, and Sld5 which are involved in the initiation of DNA replication.
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