Project description:Cancers with microsatellite instability (MSI) depend on the WRN helicase enzyme to manage issues during DNA replication caused by long stretches of (TA) repeats in the DNA. Targeting WRN is a promising strategy for treating MSI cancers, and drugs that inhibit WRN are being developed. Through a process called fragment-based screening, we developed powerful and specific drugs that block WRN's action. These drugs effectively slowed down the growth of MSI cancer models in lab and animal studies by acting like WRN is absent, leading to DNA breaks at the long TA repeats and causing DNA damage. The development of these potent and specific drugs targeting WRN in MSI cancers proves that this approach can work and also helps us understand more about WRN's role in biology.
Project description:Werner Syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The mutated gene responsible for WS encodes a DNA helicase/exonuclease protein believed to affect different aspects of transcription, replication, and DNA repair. In this study, we performed chromatin immunoprecipitation followed by sequencing (ChIP-seq) to identify regions of the genome bound by the WRN protein in Human Embryonic Kidney (HEK) 293 cells. We found 409 such genomic sites, one third of which corresponded to tRNA genes and another third of which were within RNA polymerase II transcribed genes that tended to contain guanine-rich sequences. We confirmed the specificity of several sites using WRN-depleted HEK293 cells by ChIP followed by quantitative PCR. Expression profiling of the HEK293 cells and RT-PCR analyses indicated that the transcription of the genes (including tRNAs) bound by WRN were not changed. Instead, we found a greater accumulation of WRN protein at these sites during S phase. These results suggest that the WRN protein accumulates at specific genomic sites during S phase of the cell cycle in HEK293 cells.
