title: Nuclear accumulation of the papillomavirus E1 helicase blocks S-phase progression and triggers an ATM-dependent DNA damage response.
abstract: Replication of the papillomavirus genome is initiated by the assembly of a complex between the viral E1 and E2 proteins at the origin. The E1 helicase is comprised of a C-terminal ATPase/helicase domain, a central domain that binds to the origin, and an N-terminal regulatory region that contains nuclear import and export signals mediating its nucleocytoplasmic shuttling. We previously reported that nuclear accumulation of E1 has a deleterious effect on cellular proliferation which can be prevented by its nuclear export. Here we have shown that nuclear accumulation of E1 from different papillomavirus types blocks cell cycle progression in early S phase and triggers the activation of a DNA damage response (DDR) and of the ATM pathway in a manner that requires both the origin-binding and ATPase activities of E1. Complex formation with E2 reduces the ability of E1 to induce a DDR but does not prevent cell cycle arrest. Transient viral DNA replication still occurs in S-phase-arrested cells but surprisingly is neither affected by nor dependent on induction of a DDR and of the ATM kinase. Finally, we provide evidence that a DDR is also induced in human papillomavirus type 31 (HPV31)-immortalized keratinocytes expressing a mutant E1 protein defective for nuclear export. We propose that nuclear export of E1 prevents cell cycle arrest and the induction of a DDR during the episomal maintenance phase of the viral life cycle and that complex formation with E2 further safeguards undifferentiated cells from undergoing a DDR when E1 is in the nucleus.
authors: Laboratory of Molecular Virology, Institut de Recherches Cliniques de Montréal, 110 Pine Avenue West, Montreal, Quebec, Canada H2W 1R7.
authors: Amélie
authors: A
authors: Fradet-Turcotte
authors: Fanny
authors: F
authors: Bergeron-Labrecque
authors: Cary A
authors: CA
authors: Moody
authors: Michaël
authors: M
authors: Lehoux
authors: Laimonis A
authors: LA
authors: Laimins
authors: Jacques
authors: J
authors: Archambault
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006801:Humans; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D027383:Papillomaviridae / Q000254:growth & development / Q000472:pathogenicity*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009856:Oncogene Proteins, Viral; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases