title: Adenovirus E1A oncogene induces rereplication of cellular DNA and alters DNA replication dynamics.
abstract: The oncogenic property of the adenovirus (Ad) transforming E1A protein is linked to its capacity to induce cellular DNA synthesis which occurs as a result of its interaction with several host proteins, including pRb and p300/CBP. While the proteins that contribute to the forced induction of cellular DNA synthesis have been intensively studied, the nature of the cellular DNA replication that is induced by E1A in quiescent cells is not well understood. Here we show that E1A expression in quiescent cells leads to massive cellular DNA rereplication in late S phase. Using a single-molecule DNA fiber assay, we studied the cellular DNA replication dynamics in E1A-expressing cells. Our studies show that the DNA replication pattern is dramatically altered in E1A-expressing cells, with increased replicon length, fork velocity, and interorigin distance. The interorigin distance increased by about 3-fold, suggesting that fewer DNA replication origins are used in E1A-expressing cells. These aberrant replication events led to replication stress, as evidenced by the activation of the DNA damage response. In earlier studies, we showed that E1A induces c-Myc as a result of E1A binding to p300. Using an antisense c-Myc to block c-Myc expression, our results indicate that induction of c-Myc in E1A-expressing cells contributes to the induction of host DNA replication. Together, our results suggest that the E1A oncogene-induced cellular DNA replication stress is due to dramatically altered cellular replication events and that E1A-induced c-Myc may contribute to these events.
authors.affiliation: Microbiology and Immunology Department, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Ghata
authors.initials: G
authors.lastname: Singhal
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Leo
authors.forename: Saayi Krushna Gadham
authors.initials: SK
authors.lastname: Setty
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
authors.forename: Bayar
authors.initials: B
authors.lastname: Thimmapaya
mesh_terms: D000256:Adenoviridae / Q000472:pathogenicity*; D017500:Adenovirus E1A Proteins / Q000378:metabolism*; D002273:Carcinogens / Q000378:metabolism*; D002460:Cell Line; D004261:DNA Replication; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D046228:Microarray Analysis; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism
chemical_list: D017500:Adenovirus E1A Proteins; D002273:Carcinogens; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc