Segregation of replicative DNA polymerases during S phase: DNA polymerase ε, but not DNA polymerases α/δ, are associated with lamins throughout S phase in human cells

J Biol Chem. 2012 Sep 28;287(40):33327-38. doi: 10.1074/jbc.M112.357996. Epub 2012 Aug 10.


DNA polymerases (Pol) α, δ, and ε replicate the bulk of chromosomal DNA in eukaryotic cells, Pol ε being the main leading strand and Pol δ the lagging strand DNA polymerase. By applying chromatin immunoprecipitation (ChIP) and quantitative PCR we found that at G(1)/S arrest, all three DNA polymerases were enriched with DNA containing the early firing lamin B2 origin of replication and, 2 h after release from the block, with DNA containing the origin at the upstream promoter region of the MCM4 gene. Pol α, δ, and ε were released from these origins upon firing. All three DNA polymerases, Mcm3 and Cdc45, but not Orc2, still formed complexes in late S phase. Reciprocal ChIP of the three DNA polymerases revealed that at G(1)/S arrest and early in S phase, Pol α, δ, and ε were associated with the same nucleoprotein complexes, whereas in late S phase Pol ε and Pol α/δ were largely associated with distinct complexes. At G(1)/S arrest, the replicative DNA polymerases were associated with lamins, but in late S phase only Pol ε, not Pol α/δ, remained associated with lamins. Consistently, Pol ε, but not Pol δ, was found in nuclear matrix fraction throughout the cell cycle. Therefore, Pol ε and Pol α/δ seem to pursue their functions at least in part independently in late S phase, either by physical uncoupling of lagging strand maturation from the fork progression, or by recruitment of Pol δ, but not Pol ε, to post-replicative processes such as translesion synthesis or post-replicative repair.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Cell Cycle
  • Chromatin Immunoprecipitation
  • DNA Polymerase I / chemistry*
  • DNA Polymerase II / chemistry*
  • DNA Polymerase III / chemistry*
  • DNA Replication
  • Gene Expression Regulation
  • HeLa Cells
  • Humans
  • Lamins / metabolism*
  • Nucleoproteins / chemistry
  • Polymerase Chain Reaction / methods
  • S Phase
  • Subcellular Fractions / metabolism


  • Lamins
  • Nucleoproteins
  • DNA Polymerase I
  • DNA Polymerase II
  • DNA Polymerase III