Beta human papillomavirus 8 E6 allows colocalization of non-homologous end joining and homologous recombination repair factors

• Published in: PLoS pathogens Vol. 18; no. 2; p. e1010275
• Main Authors: Hu, Changkun, Bugbee, Taylor, Dacus, Dalton, Palinski, Rachel, Wallace, Nicholas
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.02.2022; Public Library of Science (PLoS)
• Subjects: Alphapapillomavirus - genetics; Alphapapillomavirus - metabolism; Analysis; Biology and life sciences; Carcinogens; Cell Cycle; Cell Line; Deoxyribonucleic acid; Destabilization; DNA; DNA biosynthesis; DNA Breaks, Double-Stranded; DNA Damage; DNA End-Joining Repair; DNA repair; DNA Replication; DNA viruses; DNA-Activated Protein Kinase - metabolism; DNA-Binding Proteins - metabolism; DNA-dependent protein kinase; Flow cytometry; Gene expression; Growth; Homologous recombination; Homologous recombination repair; Homology; Host Microbial Interactions; Human papillomavirus; Humans; Immunofluorescence; Infections; Influence; Kinases; Lesions; Microscopy; Mimicry; Mutation; Next-generation sequencing; Non-homologous end joining; Oncogene Proteins, Viral - metabolism; Papillomavirus Infections - metabolism; Papillomavirus Infections - virology; Papillomaviruses; Physiological aspects; Protein kinase C; Rad51 Recombinase - metabolism; Recombinational DNA Repair; Repair; Research and Analysis Methods; Sequences; Tumorigenesis; Viral infections; Viruses; United States
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1010275

Beta human papillomavirus (β-HPV) are hypothesized to make DNA damage more mutagenic and potentially more carcinogenic. Double strand breaks (DSBs) are the most deleterious DNA lesion. They are typically repaired by homologous recombination (HR) or non-homologous end joining (NHEJ). HR occurs after DNA replication while NHEJ can occur at any point in the cell cycle. HR and NHEJ are not thought to occur in the same cell at the same time. HR is restricted to cells in phases of the cell cycle where homologous templates are available, while NHEJ occurs primarily during G1. β-HPV type 8 protein E6 (8E6) attenuates both repair pathways. We use a series of immunofluorescence microscopy and flow cytometry experiments to better define the impact of this attenuation. We found that 8E6 causes colocalization of HR factors (RPA70 and RAD51) with an NHEJ factor (activated DNA-PKcs or pDNA-PKcs) at persistent DSBs. 8E6 also causes RAD51 foci to form during G1. The initiation of NHEJ and HR at the same lesion could lead to antagonistic DNA end processing. Further, HR cannot be readily completed in an error-free manner during G1. Both aberrant repair events would cause deletions. To determine if these mutations were occurring, we used next generation sequencing of the 200kb surrounding a CAS9-induced DSB. 8E6 caused a 21-fold increase in deletions. Chemical and genetic inhibition of p300 as well as an 8E6 mutant that is incapable of destabilizing p300 demonstrates that 8E6 is acting via p300 destabilization. More specific chemical inhibitors of DNA repair provided mechanistic insight by mimicking 8E6-induced dysregulation of DNA repair in a virus-free system. Specifically, inhibition of NHEJ causes RAD51 foci to form in G1 and colocalization of RAD51 with pDNA-PKcs.