HMGB1 interacts with XPA to facilitate the processing of DNA interstrand crosslinks in human cells

Abstract

Many effective agents used in cancer chemotherapy cause DNA interstrand crosslinks (ICLs), which covalently link both strands of the double helix together resulting in cytotoxicity. ICLs are thought to be processed by proteins from a variety of DNA repair pathways; however, a clear understanding of ICL recognition and repair processing in human cells is lacking. Previously, we found that the high mobility group box 1 (HMGB1) protein bound to triplex-directed psoralen ICLs (TFO-ICLs) in vitro, cooperatively with NER damage recognition proteins, promoted removal of UVC-induced lesions and facilitated error-free repair of TFO-ICLs in mouse fibroblasts. Here, we demonstrate that HMGB1 recognizes TFO-ICLs in human cells, and its depletion increases ICL-induced mutagenesis in human cells without altering the mutation spectra. In contrast, HMGB1 depletion in XPA-deficient human cells significantly altered the ICL-induced mutation spectrum from predominantly T→A to T→G transversions. Moreover, the recruitment of XPA and HMGB1 to the ICLs is co-dependent. Finally, we show that HMGB1 specifically introduces negative supercoils in ICL-containing plasmids in HeLa cell extracts. Taken together, our data suggest that in human cells, HMGB1 functions in association with XPA on ICLs and facilitates the formation of a favorable architectural environment for ICL repair processing.

Involvement of translesion synthesis DNA polymerases in DNA interstrand crosslink repair

“…The recruitment of NER proteins to ICLs has been directly demonstrated in G1 cells, lending support to the studies conducted with reporter plasmids [32]. In addition to NER factors, mismatch repair (MMR) and HMG proteins have been shown to interact with NER proteins at ICLs and may therefore also contribute to replication-independent repair of ICLs [33, 34]. …”

Targeting the High-Mobility Group Box 3 Protein Sensitizes Chemoresistant Ovarian Cancer Cells to Cisplatin

“…Cell culture and determination of cisplatin LD 50 values Cells were purchased from ATCC where they perform short tandem repeat profiling for cell line authentication. Cells were cultured as described previously (11). Cells were grown to 80%-90% confluency and were passaged at least three times after thawing before any experiments were performed and were cultured for a period of 6 months to perform all the experiments and repetitions.…”

“…We have previously demonstrated that the high-mobility group box 1 (HMGB1) protein binds with high affinity to ICLs and acts as an NER cofactor in human cells (10,11). Other members of the HMGB family, HMGB2 and HMGB3, share sequence and structural similarities with HMGB1 and possess two box domains, boxes A and B; where box A binds DNA and box B bends DNA, and acidic C-terminal tails.…”

Yeast HMO1: Linker Histone Reinvented

“…The functional consequences of HMGB1 binding to damaged DNA have been alternately suggested to be a shielding of the lesion from the repair machinery or enhanced recognition of the damaged site (99,101,102). For example, HMGB1 has been reported to sensitize cells to cisplatin by impeding repair, perhaps influenced by the cellular redox state (103,104); conversely, human HMGB1 has been reported to facilitate nucleotide excision repair (NER) by recruiting the NER protein XPA to interstrand cross-links (105). Interestingly, the recruitment of XPA to nondamaged sites was increased in HMGB1-depleted cells, suggesting that HMGB1 not only promotes NER but also facilitates the specificity of XPA-mediated damage recognition.…”