Kolesnichenko, M. | bioRxiv Science

bioRxiv2021

TSG101 Associates with PARP1 and is Essential for PARylation and DNA Damage-induced NF-κB Activation

In a genome-wide screening for components of the dsDNA-break-induced IKK-NF-{kappa}B pathway we identified scores of regulators, including tumor susceptibility protein TSG101. TSG101 is essential for DNA damage-induced formation of cellular poly(ADP-ribose) (PAR). TSG101 directly 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-IKK{gamma} signalosome, which triggers IKK activation, is impaired. According to its requirement for PARP1 and NF-{kappa}B 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 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.

molecular biology↗

bioRxiv2019

A novel IKK- and proteasome-independent mechanism of RelA activation triggers senescence associated secretome via transcriptional repression of NFKBIA

The I{kappa}B kinase (IKK) - NF-{kappa}B pathway is activated as part of the DNA damage response and controls both resistance to apoptosis and inflammation. How these different functions are achieved remained unknown. We demonstrate here that DNA double strand breaks elicit two subsequent phases of NF-{kappa}B activation in vivo and in vitro, which are mechanistically and functionally distinct. RNA-sequencing reveals that the first phase controls anti-apoptotic gene expression, while the second drives expression of senescence-associated secretory phenotype (SASP) genes. The first, rapidly activated phase is driven by the ATM-PARP1-TRAF6-IKK cascade, which triggers proteasomal destruction of I{kappa}B and is terminated through I{kappa}B (NFKBIA) re-expression. The second phase is activated days later in senescent cells but is independent of IKK and the proteasome. An altered phosphorylation status of p65, in part driven by GSK3{beta}, results in transcriptional silencing of NFKBIA and IKK-independent, constitutive activation of NF-{kappa}B in senescence. Collectively, our study reveals a novel physiological mechanism of NF-{kappa}B activation with important implications for genotoxic cancer treatment.

cell biology↗