Cell cycle - Start of DNA replication in early S phase

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DNA replication and S phase progression

DNA replication is a key event of cell proliferation.

Replication begins with the ordered assembly of a multiprotein complex called the prereplicative complex (pre-RC). Pre-RC formation occurs during late M and early G1 phases of the cell cycle and licenses the DNA for replication during S phase. Transcription of many eukaryotic DNA replication machinery genes is activated by E2F transcriptional factors (e.g. E2F1/DP1 dimer).

Pre-RC consists of the origin recognition complex (ORC complex), the cell division cycle 6 homolog (CDC18L), Cdt1 and the minichromosome maintenance protein complex (MCM complex). Pre-RC components are recruited to the origins in a stepwise manner beginning with the ORC. Subunit 1 of ORC complex (ORC1L) may be recruited to origins by chromobox protein homolog 5 (HP1) [1]. Subunits ORC2L, ORC3L, ORC4L and ORC5L form core complex, its stability is regulated by ORC1L [2], [3].

ORC complex recruits CDC18L and Cdt1, which are both required for the subsequent loading of the MCM complex [4]. CDC18L is capable of inducing the binding between Cdt1 and MCM complex [5]. The MCM complex is a heterohexamer which plays a role of the replicative helicase in eukaryotic cells. Each of the six subunits is required for replication [6]. It is shown that MCM2 and MCM3/5 are regulatory subunits. MCM2 and MCM3/5 inhibit the helicase activity of the MCM4/6/7 [7] by converting its double trimer structure into a heterotetramer or heteropentamer, respectively [8].

Then cell division cycle 7-related protein kinase 2 (CDK2) and/or cell division cycle 7-related protein kinase (CDC7) and minichromosome maintenance deficient 10 protein (Mcm10) stimulate recruiting of CDC45-related protein (CDC45L) to the Pre-RC. Recruiting CDC45L and some other proteins promote maturation Pre-RC in pre-initiation complex (pre-IC). CDC45L recruits CDK2 to the replication foci, resulting in histon H1 phosphorylation, chromatin decondensation, and facilitation of fork progression [9].

In addition, replication proteins (RPA) are bound with the origin. There are three forms of RPA (RPA1, RPA2 and RPA3). Trimeric complex of these proteins is required for an association with DNA [10].

Serine/threonine protein phosphatase 2A (PP2A) activates by dephosphorylation DNA polymerase alpha/primase in late G1 phase. DNA polymerase alpha/primase is the only enzyme capable of initiating DNA synthesis de novo by first synthesizing an RNA primer and then extending the primer by polymerization to produce a short 30-nucleotide DNA extension. DNA polymerase alpha/primase forms complex with MCM2 in early S-phase. Then formation of new MCM2/ DNA polymerase alpha/primase complexes might be prevented by CDK2/CyclinA phosphorylation of DNA polymerase alpha/primase in late-S-phase [11].

CDK2/Cyclins also inhibit by phoshorylation some eukaryotic DNA replication machinery elements in late S-phase. There are MCM4/6/7 helicase [12], CDC18L [13] and Cdt1. ORC1L, CDC18L, Cyclin A are inhibited by ubiqitination with help of APC/hCdh complex. Cdt1 is regulated by Geminin and ubiqitination with help SCF complex.

References:

  1. Lidonnici MR, Rossi R, Paix?o S, Mendoza-Maldonado R, Paolinelli R, Arcangeli C, Giacca M, Biamonti G, Montecucco A
    Subnuclear distribution of the largest subunit of the human origin recognition complex during the cell cycle. Journal of cell science 2004 Oct 15;117(Pt 22):5221-31
  2. Dhar SK, Delmolino L, Dutta A
    Architecture of the human origin recognition complex. The Journal of biological chemistry 2001 Aug 3;276(31):29067-71
  3. Vashee S, Simancek P, Challberg MD, Kelly TJ
    Assembly of the human origin recognition complex. The Journal of biological chemistry 2001 Jul 13;276(28):26666-73
  4. Takeda DY, Dutta A
    DNA replication and progression through S phase. Oncogene 2005 Apr 18;24(17):2827-43
  5. Cook JG, Chasse DA, Nevins JR
    The regulated association of Cdt1 with minichromosome maintenance proteins and Cdc6 in mammalian cells. The Journal of biological chemistry 2004 Mar 5;279(10):9625-33
  6. Davey MJ, Indiani C, O'Donnell M
    Reconstitution of the Mcm2-7p heterohexamer, subunit arrangement, and ATP site architecture. The Journal of biological chemistry 2003 Feb 14;278(7):4491-9
  7. Sato M, Gotow T, You Z, Komamura-Kohno Y, Uchiyama Y, Yabuta N, Nojima H, Ishimi Y
    Electron microscopic observation and single-stranded DNA binding activity of the Mcm4,6,7 complex. Journal of molecular biology 2000 Jul 14;300(3):421-31
  8. Basauri L, Selman JM
    Intracranial arachnoidal cysts. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery 1992 Mar;8(2):101-4
  9. Alexandrow MG, Hamlin JL
    Chromatin decondensation in S-phase involves recruitment of Cdk2 by Cdc45 and histone H1 phosphorylation. The Journal of cell biology 2005 Mar 14;168(6):875-86
  10. Bochkareva E, Korolev S, Bochkarev A
    The role for zinc in replication protein A. The Journal of biological chemistry 2000 Sep 1;275(35):27332-8
  11. Dehde S, Rohaly G, Schub O, Nasheuer HP, Bohn W, Chemnitz J, Deppert W, Dornreiter I
    Two immunologically distinct human DNA polymerase alpha-primase subpopulations are involved in cellular DNA replication. Molecular and cellular biology 2001 Apr;21(7):2581-93
  12. Fujita M, Yamada C, Tsurumi T, Hanaoka F, Matsuzawa K, Inagaki M
    Cell cycle- and chromatin binding state-dependent phosphorylation of human MCM heterohexameric complexes. A role for cdc2 kinase. The Journal of biological chemistry 1998 Jul 3;273(27):17095-101
  13. Yim H, Jin YH, Park BD, Choi HJ, Lee SK
    Caspase-3-mediated cleavage of Cdc6 induces nuclear localization of p49-truncated Cdc6 and apoptosis. Molecular biology of the cell 2003 Oct;14(10):4250-9

  1. Lidonnici MR, Rossi R, Paix?o S, Mendoza-Maldonado R, Paolinelli R, Arcangeli C, Giacca M, Biamonti G, Montecucco A
    Subnuclear distribution of the largest subunit of the human origin recognition complex during the cell cycle. Journal of cell science 2004 Oct 15;117(Pt 22):5221-31
  2. Dhar SK, Delmolino L, Dutta A
    Architecture of the human origin recognition complex. The Journal of biological chemistry 2001 Aug 3;276(31):29067-71
  3. Vashee S, Simancek P, Challberg MD, Kelly TJ
    Assembly of the human origin recognition complex. The Journal of biological chemistry 2001 Jul 13;276(28):26666-73
  4. Takeda DY, Dutta A
    DNA replication and progression through S phase. Oncogene 2005 Apr 18;24(17):2827-43
  5. Cook JG, Chasse DA, Nevins JR
    The regulated association of Cdt1 with minichromosome maintenance proteins and Cdc6 in mammalian cells. The Journal of biological chemistry 2004 Mar 5;279(10):9625-33
  6. Davey MJ, Indiani C, O'Donnell M
    Reconstitution of the Mcm2-7p heterohexamer, subunit arrangement, and ATP site architecture. The Journal of biological chemistry 2003 Feb 14;278(7):4491-9
  7. Sato M, Gotow T, You Z, Komamura-Kohno Y, Uchiyama Y, Yabuta N, Nojima H, Ishimi Y
    Electron microscopic observation and single-stranded DNA binding activity of the Mcm4,6,7 complex. Journal of molecular biology 2000 Jul 14;300(3):421-31
  8. Basauri L, Selman JM
    Intracranial arachnoidal cysts. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery 1992 Mar;8(2):101-4
  9. Alexandrow MG, Hamlin JL
    Chromatin decondensation in S-phase involves recruitment of Cdk2 by Cdc45 and histone H1 phosphorylation. The Journal of cell biology 2005 Mar 14;168(6):875-86
  10. Bochkareva E, Korolev S, Bochkarev A
    The role for zinc in replication protein A. The Journal of biological chemistry 2000 Sep 1;275(35):27332-8
  11. Dehde S, Rohaly G, Schub O, Nasheuer HP, Bohn W, Chemnitz J, Deppert W, Dornreiter I
    Two immunologically distinct human DNA polymerase alpha-primase subpopulations are involved in cellular DNA replication. Molecular and cellular biology 2001 Apr;21(7):2581-93
  12. Fujita M, Yamada C, Tsurumi T, Hanaoka F, Matsuzawa K, Inagaki M
    Cell cycle- and chromatin binding state-dependent phosphorylation of human MCM heterohexameric complexes. A role for cdc2 kinase. The Journal of biological chemistry 1998 Jul 3;273(27):17095-101
  13. Yim H, Jin YH, Park BD, Choi HJ, Lee SK
    Caspase-3-mediated cleavage of Cdc6 induces nuclear localization of p49-truncated Cdc6 and apoptosis. Molecular biology of the cell 2003 Oct;14(10):4250-9

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