TSG101 associates with PARP1 and is essential for PARylation and DNA damage‐induced NF‐κB activation

Abstract

In a genome‐wide screening for components of the dsDNA‐break‐induced IKK‐NF‐κB pathway, we identified scores of regulators, including tumor susceptibility gene TSG101. TSG101 is essential for DNA damage‐induced formation of cellular poly(ADP‐ribose) (PAR). TSG101 binds to PARP1 and is required for PARP1 activation. This function of TSG101 is independent of its role in the ESCRT‐I endosomal sorting complex. In the absence of TSG101, the PAR‐dependent formation of a nuclear PARP1‐IKKγ signalosome, which triggers IKK activation, is impaired. According to its requirement for PARP1 and NF‐κB activation, TSG101‐deficient cells are defective in DNA repair and apoptosis protection. Loss of TSG101 results in PARP1 trapping at damage sites and mimics the effect of pharmacological PARP inhibition. We also show that the loss of TSG101 in connection with inactivated tumor suppressors BRCA1/2 in breast cancer cells is lethal. Our results imply TSG101 as a therapeutic target to achieve synthetic lethality in cancer treatment. image A genome‐wide siRNA screen revealed scores of hits that selectively regulate NF‐κB activation by DNA double‐strand breaks, including tumor suppressor TSG101. TSG101 is here found to be essential for cellular poly(ADP ribosylation) and DNA damage‐induced IKK‐NF‐κB activation. TSG101 binds to PARP1 via its coiled‐coil domain and is required for poly(ADP ribosylation). TSG101 activates PARP1 and IKK signaling independently of its role in the ESCRT pathway. Depletion of TSG101 or pharmacological PARP1 inhibition equivalently causes PARP1 trapping at DNA damage foci. TSG101 protects genotoxic stress‐exposed cells from the accumulation of DNA lesions and from apoptosis. BRCA1/2‐deficient breast cancer cells are hypersensitive to the loss of TSG101, indicating synthetic lethality.