Cell cycle‐regulated ubiquitination of tankyrase 1 by RNF8 and ABRO1/BRCC36 controls the timing of sister telomere resolution

Abstract

Timely resolution of sister chromatid cohesion in G2/M is essential for genome integrity. Resolution at telomeres requires the poly (ADP-ribose) polymerase tankyrase 1, but the mechanism that times its action is unknown. Here, we show that tankyrase 1 activity at telomeres is controlled by a ubiquitination/deubiquitination cycle depending on opposing ubiquitin ligase and deubiquitinase activities. In late S/G2 phase, the DNA damage-responsive E3 ligase RNF8 conjugates K63-linked ubiquitin chains to tankyrase 1, while in G1 phase such ubiquitin chains are removed by BRISC, an ABRO1/BRCC36-containing deubiquitinase complex. We show that K63-linked ubiquitin chains accumulate on tankyrase 1 in late S/G2 to promote its stabilization, association with telomeres, and resolution of cohesion. Timing of this posttranslational modification coincides with the ATM-mediated DNA damage response that occurs on functional telomeres following replication in G2. Removal of ubiquitin chains is controlled by ABRO1/BRCC36 and occurs as cells exit mitosis and enter G1, ensuring that telomere cohesion is not resolved prematurely in S phase. Our studies suggest that a cell cycle-regulated posttranslational mechanism couples resolution of telomere cohesion with completion of telomere replication to ensure genome integrity.

Whole proteome analysis of human tankyrase knockout cells reveals targets of tankyrase-mediated degradation

“…TNKS lentiviral plasmids contain full-length Flag-epitope tagged TNKS1 or TNKS2 cloned into lentiviral vector pLKO.1ps 64 , 65 . The TRF1 plasmid contains full-length myc-epitope tagged TRF1 cloned into retroviral vector pLPC 66 .…”

How to Inactivate Human Ubiquitin E3 Ligases by Mutation

“…Despite less frequently, in a number of investigations, the Cys involved in zinc coordination have also been efficiently mutated into serine. Indeed, this type of point mutation that results on E3 ligase inactivation has served to uncover, among others, the role of MDM2, RNF8, and SIAH1 RING E3s in cell cycle regulation, DNA damage response and Wnt signalling, respectively (Ji et al, 2017;Tian et al, 2017;Tripathi and Smith, 2017). Additionally, although there are fewer examples, it has been demonstrated that mutating the His into Glu, Tyr or Arg is sufficient to inactivate the ligase activity of MKRN1, RNF2, and RNF43 E3s, respectively (Xia et al, 2014;Loregger et al, 2015;Lee et al, 2018b; Figure 3).…”

ABRO1 promotes NLRP3 inflammasome activation through regulation of NLRP3 deubiquitination

“…Therefore, ABRO1 does not interact with BRCA1 but serves as a scaffold protein and recruits the rest of the components, including NBA1, BRE, and BRCC3, to form the BRISC (Feng et al, 2010). So far, only a few substrates of BRISC have been identified, including the type 1 interferon (IFN) receptor chain 1 (IFNAR1) (Zheng et al, 2013), the essential spindle assembly factor nuclear mitotic apparatus (NuMA) (Yan et al, 2015a), the poly (ADP-ribose) polymerase tankyrase 1 (Tripathi & Smith, 2017), and the HIV-1 Tat protein (Xu et al, 2018).…”