Human PUS7 in tRNA pseudouridylation

Pseudouridine is the first discovered and the most frequent modification in RNA. However, its biological functions in physiology and human diseases are largely unknown. Here, we show that pseudouridine synthase PUS7 is differentially expressed in glioblastoma patient tissues verse non-tumor brain tissues, and highly expressed in patient brain-derived cancer stem cells, compared to normal brain-derived neural stem cells. Upregulated expression of PUS7 predicts worse survival in glioblastoma patients in multiple databases. Indeed, we show that PUS7 plays an important role in regulating the self-renewal and tumorigenesis of glioblastoma stem cells. Overexpression of the wild type but not the catalytically inactive PUS7 increases the growth and self-renewal of GSCs. In contrast, knockdown of PUS7 dramatically suppresses GSC growth, self-renewal and tumorigenesis. Mechanistically, knockdown of PUS7 activates interferon pathway through translational control of TYK2 via PUS7-regulated tRNAs. Moreover, we have identified chemical inhibitors for PUS7 in this study. These chemical compounds target pseudouridine modification and suppress GSC growth and tumorigenesis, providing a potential therapeutic tool for GBM treatment. mRNA, rRNA, and small RNA Ψ-seq to detect PUS7 dependent pesudouridne sites in PBT003 cells, NSC006 and G13 treatment cells