RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors

Seetha V. Srinivasan, Christopher N. Mayhew, Sandy Schwemberger, William Zagorski, Erik S. Knudsen

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The retinoblastoma tumor suppressor (RB) is functionally inactivated in many human cancers. Classically, RB functions to repress E2F-mediated transcription and inhibit cell cycle progression. Consequently, RB ablation leads to loss of cell cycle control and aberrant expression of E2F target genes. Emerging evidence indicates a role for RB in maintenance of genomic stability. Here, mouse adult fibroblasts were utilized to demonstrate that aberrant DNA content in RB-deficient cells occurs concomitantly with an increase in levels and chromatin association of DNA replication factors. Furthermore, following exposure to nocodazole, RB-proficient cells arrest with 4 N DNA content, whereas RB-deficient cells bypass the mitotic block, continue DNA synthesis, and accumulate cells with higher ploidy and micronuclei. Under this condition, RB-deficient cells also retain high levels of tethered replication factors, MCM7 and PCNA, indicating that DNA replication occurs in these cells under nonpermissive conditions. Exogenous expression of replication factors Cdc6 or Cdt1 in RB-proficient cells does not recapitulate the RB-deficient cell phenotype. However, ectopic E2F expression in RB-proficient cells elevated ploidy and bypassed the response to nocodazole-induced cessation of DNA replication in a manner analogous to RB loss. Collectively, these results demonstrate that deregulated S phase control is a key mechanism by which RB-deficient cells acquire elevated ploidy.

Original languageEnglish (US)
Pages (from-to)23867-23877
Number of pages11
JournalJournal of Biological Chemistry
Volume282
Issue number33
DOIs
StatePublished - Aug 17 2007

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Ploidies
DNA Replication
DNA
Nocodazole
Cells
Phase control
Proliferating Cell Nuclear Antigen
Transcription
Fibroblasts
Ablation
Chromatin
Tumors
Genes
Association reactions
Retinoblastoma
Genomic Instability
Cell Cycle Checkpoints
S Phase
Neoplasms
Cell Cycle

ASJC Scopus subject areas

  • Biochemistry

Cite this

Srinivasan, S. V., Mayhew, C. N., Schwemberger, S., Zagorski, W., & Knudsen, E. S. (2007). RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors. Journal of Biological Chemistry, 282(33), 23867-23877. https://doi.org/10.1074/jbc.M700542200

RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors. / Srinivasan, Seetha V.; Mayhew, Christopher N.; Schwemberger, Sandy; Zagorski, William; Knudsen, Erik S.

In: Journal of Biological Chemistry, Vol. 282, No. 33, 17.08.2007, p. 23867-23877.

Research output: Contribution to journalArticle

Srinivasan, SV, Mayhew, CN, Schwemberger, S, Zagorski, W & Knudsen, ES 2007, 'RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors', Journal of Biological Chemistry, vol. 282, no. 33, pp. 23867-23877. https://doi.org/10.1074/jbc.M700542200
Srinivasan, Seetha V. ; Mayhew, Christopher N. ; Schwemberger, Sandy ; Zagorski, William ; Knudsen, Erik S. / RB loss promotes aberrant ploidy by deregulating levels and activity of DNA replication factors. In: Journal of Biological Chemistry. 2007 ; Vol. 282, No. 33. pp. 23867-23877.
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