TDP2/TTRAP Is the Major 5′-Tyrosyl DNA Phosphodiesterase Activity in Vertebrate Cells and Is Critical for Cellular Resistance to Topoisomerase II-induced DNA Damage

Abstract

Topoisomerase II (Top2) activity involves an intermediate in which the topoisomerase is covalently bound to a DNA double-strand break via a 5′-phosphotyrosyl bond. Although these intermediates are normally transient, they can be stabilized by antitumor agents that act as Top2 “poisons,” resulting in the induction of cytotoxic double-strand breaks, and they are implicated in the formation of site-specific translocations that are commonly associated with cancer. Recently, we revealed that TRAF and TNF receptor-associated protein (TTRAP) is a 5′-tyrosyl DNA phosphodiesterase (5′-TDP) that can cleave 5′-phosphotyrosyl bonds, and we denoted this protein tyrosyl DNA phosphodiesterase-2 (TDP2). Here, we have generated TDP2-deleted DT40 cells, and we show that TDP2 is the major if not the only 5′-TDP activity present in vertebrate cells. We also show that TDP2-deleted DT40 cells are highly sensitive to the anticancer Top2 poison, etoposide, but are not hypersensitive to the Top1 poison camptothecin or the DNA-alkyating agent methyl methanesulfonate. These data identify an important mechanism for resistance to Top2-induced chromosome breakage and raise the possibility that TDP2 is a significant factor in cancer development and treatment.

Involvement of the host DNA-repair enzyme TDP2 in formation of the covalently closed circular DNA persistence reservoir of hepatitis B viruses

“…The preference of TDP2 for 5′ phosphotyrosyl bonds is consistent with recent X-ray data (27)(28)(29), but TDP2 also is active on 3′-substrates (20,26,30). Although TDP2 likely is the only enzyme of its kind (30), complete knockout of TDP2 in chicken DT40 cells and in mice was not lethal (20), possibly reflecting the power of redundancy in DNA repair. Notably, TDP2 recently also has been found to represent the "unlinkase" activity that can remove the covalently linked VPg from poliovirus RNA (31).…”

An RNA virus hijacks an incognito function of a DNA repair enzyme

“…From the changes in the subcellular localization of TDP2 that occur at later times postinfection, we propose that picornaviruses exclude TDP2 from RNA replication complexes to protect VPg-linked progeny RNAs required for encapsidation. Although TDP2 is the only known 5′-tyrosyl-DNA phosphodiesterase found in vertebrate cells (13), it was initially disregarded as a putative VPg unlinkase candidate for several reasons. First, it has been reported that VPg unlinkase cannot cleave the tyrosylnucleic acid linkage of a synthetic 5′-tyrosyl-DNA substrate (14).…”

Mutant p53 cooperates with ETS2 to promote etoposide resistance

“…We demonstrated that mtp53 regulates the expression of the TDP2 gene, which encodes a protein that has 59-tyrosyl DNA phosphodiesterase activity that is required for the repair of etoposide-induced DNA double-strand breaks (Cortes Ledesma et al 2009;Adhikari et al 2011;Zeng et al 2011). The identification of TDP2 as a mtp53 target is important because it reveals an enzymatic activity that can be targeted to sensitize cells that express mtp53.…”

“…We manually curated this set of 17 genes and found TDP2, a gene that has a unique and apparently nonredundant role in the repair of etoposide-induced DNA damage (Supplemental Table S5). TDP2 was initially identified as a protein that associates with the TNF receptor and has recently been shown to have 59-tyrosyl DNA phosphodiesterase activity that is required for the repair of etoposide-induced DNA double-strand breaks (Pype et al 2000;Cortes Ledesma et al 2009;Li et al 2011b;Zeng et al 2011). Given that mtp53 can promote etoposide resistance, we speculated that TDP2 may represent a transcriptional target of mtp53 that contributes to chemotherapy resistance.…”