Werner syndrome WRN helicase alters gene expression in a G-quadruplex DNA-dependent manner to antagonize a pro-senescence gene expression program

Werner syndrome (WS) is a human adult progeroid syndrome caused by loss-of-function mutations in the WRN RECQ helicase gene. We analyzed mRNA and miRNA expression in fibroblasts from WS patients and in fibroblasts depleted of WRN protein in order to determine the role of WRN in transcription regulation, and to identify genes and miRNAs that might drive WS disease pathogenesis. Genes altered in WS cells participate in cellular growth, proliferation and survival; in tRNA charging and in oncogenic signaling; and in connective tissue and developmental networks. Genes down-regulated in WS cells were highly enriched in Gquadruplex (G4) DNA motifs, indicating G4 motifs are physiologic substrates for WRN. In contrast, there was a remarkable, coordinate up-regulation of nearly all of the cytoplasmic tRNA synthetases and of genes associated with the senescence-associated secretory phenotype (SASP). These results identify canonical pathways that may drive the pathogenesis of Werner syndrome and associated disease risks. Primary fibroblasts from 6 patients and 8 matched normal controls, and in 9 primary diploid fibroblasts. The 9 primary diploid fibroblasts included 3 depleted of the WRN protein by WRN-specific shRNA, 3 controls, and 3 scrambled shRNA with no known target sequence in the human genome.