Nucleotide Excision Repair of Aflatoxin-Induced DNA Damage within the 3D Human Genome Organization

Aflatoxin B1 (AFB1), a potent carcinogenic mycotoxin, is known to contribute to liver cancer development. Within the cell, bioactivated AFB1 intercalates into the DNA double helix, forming bulky DNA adducts that lead to mutagenesis if left unrepaired. Here, we adapted the tXR-seq method to map the nucleotide excision repair of AFB1-induced DNA lesions at genome-wide level. Our research uncovered that transcription-coupled repair plays a major role in repairing the AFB1-induced DNA lesions. We identified a distinctive length distribution pattern for the excision products released during repair, suggesting a unique dual incision mechanism for AFB1-induced DNA lesions. Notably, we revealed that repair activity is more pronounced on chromosomes closer to the nuclear center and A compartments undergo faster repair compared with B compartments. Additionally, we observed higher repair activity within regions encompassing TAD boundaries and loop anchors. This study provides insights into the interplay between repair, transcription, and 3D genome organization, shedding light on the mechanisms behind AFB1-associated liver cancer development. Overall design: To investigate the impact of 3D genome organization on nucleotide excision repair, we adapted the tXR-seq method to map the genome-wide repair of AFB1-induced DNA lesions and determined the repair signals at multiple levels of genomic organizations.