Phenotypic screen identifies JAK2 as a major regulator of FAT10 expression.

Abstract

FAT10 is a ubiquitin-like protein suggested to target proteins for proteasomal degradation. It is highly upregulated upon pro-inflammatory cytokines namely TNFα, IFNγ and IL6, and was found to be highly expressed in various epithelial cancers. Evidence suggests that FAT10 is involved in cancer development and may have a pro- tumorigenic role. However, its biological role is still unclear as is its biochemical and cellular regulation. To identify pathways underlying FAT10 expression in the context of pro-inflammatory stimulation, which characterizes the cancerous environment, we implemented a phenotypic transcriptional reporter screen with a library of annotated compounds. We identified AZ960, a potent JAK2 inhibitor, which significantly downregulates FAT10 under pro-inflammatory cytokines, in an NFκB-independent manner. We validated JAK2 as a major regulator of FAT10 expression via knockdown, and suggest that the transcriptional effects are mediated through pSTAT1/3/5. Overall, we elucidated a pathway regulating FAT10 transcription and discovered a tool compound to chemically downregulate FAT10 expression, and further study its biology.