PARP1-MGMT complex underpins pathway crosstalk in O6-methylguanine repair

• Published in: Journal of hematology and oncology 2022-10, Vol.15 (1), p.1-6, Article 146
• Main Authors: Cropper, Jodie D, Alimbetov, Dauren S, Brown, Kevin T. G, Likhotvorik, Rostislav I, Robles, Andrew J, Guerra, James T, He, Boxue, Chen, Yidong, Kwon, Youngho, Kurmasheva, Raushan T
• Format: Article
• Language: English
• Subjects: Adducts; Alkylating agents; Base excision repair; Blood cancer; Cancer therapy; Catalysis; Chromatin; Computer simulation; Cooperativity; Correspondence; Cytotoxicity; Dealkylation; DNA damage; DNA damage and repair; DNA methyltransferase; DNA repair; Ewings sarcoma; Hematology; Methylguanine; MGMT; Mutation; O6-Methylguanine; O6-methylguanine-DNA methyltransferase; Oncology; PARP1; Pediatrics; Phosphorylation; Physiological aspects; Poly(ADP-ribose) polymerase; Post-translation; Protein interaction; Proteins; Ribose; Sarcoma; Temozolomide; Ubiquitination
• ISSN: 1756-8722; 1756-8722
• DOI: 10.1186/s13045-022-01367-4

DNA lesions induced by alkylating agents are repaired by two canonical mechanisms, base excision repair dependent on poly(ADP) ribose polymerase 1 (PARP1) and the other mediated by O.sup.6-methylguanine (O.sup.6meG)-DNA methyltransferase (MGMT) in a single-step catalysis of alkyl-group removal. O.sup.6meG is the most cytotoxic and mutagenic lesion among the methyl adducts induced by alkylating agents. Although it can accomplish the dealkylation reaction all by itself as a single protein without associating with other repair proteins, evidence is accumulating that MGMT can form complexes with repair proteins and is highly regulated by a variety of post-translational modifications, such as phosphorylation, ubiquitination, and others. Here, we show that PARP1 and MGMT proteins interact directly in a non-catalytic manner, that MGMT is subject to PARylation by PARP1 after DNA damage, and that the O.sup.6meG repair is enhanced upon MGMT PARylation. We provide the first evidence for the direct DNA-independent PARP1-MGMT interaction. Further, PARP1 and MGMT proteins also interact via PARylation of MGMT leading to formation of a novel DNA damage inducible PARP1-MGMT protein complex. This catalytic interaction activates O.sup.6meG repair underpinning the functional crosstalk between base excision and MGMT-mediated DNA repair mechanisms. Furthermore, clinically relevant 'chronic' temozolomide exposure induced PARylation of MGMT and increased binding of PARP1 and MGMT to chromatin in cells. Thus, we provide the first mechanistic description of physical interaction between PARP1 and MGMT and their functional cooperation through PARylation for activation of O.sup.6meG repair. Hence, the PARP1-MGMT protein complex could be targeted for the development of advanced and more effective cancer therapeutics, particularly for cancers sensitive to PARP1 and MGMT inhibition. Keywords: DNA damage and repair, Protein interaction, PARP1, MGMT, O.sup.6-Methylguanine, Cancer therapy, Ewing sarcoma