title: 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.
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, 1400 Barbara Jordan Boulevard, Austin, TX 78723, USA.
authors.forename: Anirban
authors.initials: A
authors.lastname: Mukherjee
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, 1400 Barbara Jordan Boulevard, Austin, TX 78723, USA karen.vasquez@austin.utexas.edu.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Vasquez
mesh_terms: D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004587:Electrophoresis, Agar Gel; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D034622:RNA Interference; D051760:Xeroderma Pigmentosum Group A Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D024243:HMGB1 Protein; C585491:HMGB1 protein, human; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; D004247:DNA