The WRN protein accumulates at tRNA and G-rich regions during S phase in HEK293 cells.. Homo sapiens

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. Overall design: ChIP-seq analysis of WRN genome binding