DNA replication factor CDT1 explained

CDT1 (Chromatin licensing and DNA replication factor 1) is a protein that in humans is encoded by the CDT1 gene.^{[1] [2] [3] [4]} It is a licensing factor that functions to limit DNA from replicating more than once per cell cycle.

Role in pre-replication complexes

The protein encoded by this gene is a key licensing factor in the assembly of pre-replication complexes (pre-RC), which occurs during the G1 phase of the cell cycle. In the assembly of pre-RCs, origin recognition complexes (ORC1-6) recognize and bind to DNA replication origins. CDT1, along with the protein CDC6, are then recruited to the forming pre-RC, followed by minichromosome maintenance complexes (MCM2-7).^[5]

The activity of CDT1 during the cell cycle is tightly regulated during the S phase by the protein geminin, which inhibits it, and by SCF^SKP2, which ubiquinates the protein to tag it for proteasomal degradation.^[6] This regulation is important in preventing relicensing, thus ensuring that DNA is only replicated once per cell cycle.

Orthologs

CDT1 belongs to a family of replication proteins conserved from yeast to humans. Examples of orthologs in other species include:

• S. pombe – CDT1 (CDC10-dependent transcript 1)^[7]
• Drosophila melanogaster – 'double parked' or Dup^[8]
• Xenopus laevis - CDT1^[9]

Interactions

DNA replication factor CDT1 has been shown to interact with SKP2.^[10] Cdt1 is recruited by the origin recognition complex in origin licensing. Null-mutations for CDT1 are lethal in yeast; the spores undergo mitosis without DNA replication. The overexpression of CDT1 causes rereplication in H. sapiens, which activates the Chk1 pathway, preventing entry into mitosis.^[11]

Further reading

• Xouri G, Dimaki M, Bastiaens PI, Lygerou Z . Cdt1 interactions in the licensing process: a model for dynamic spatiotemporal control of licensing. . Cell Cycle . 6 . 13 . 1549–52 . 2007 . 17598984 . 10.4161/cc.6.13.4455 . free .
• Andersson B, Wentland MA, Ricafrente JY . A "double adaptor" method for improved shotgun library construction. . Anal. Biochem. . 236 . 1 . 107–13 . 1996 . 8619474 . 10.1006/abio.1996.0138 . etal.
• Yu W, Andersson B, Worley KC . Large-scale concatenation cDNA sequencing. . Genome Res. . 7 . 4 . 353–8 . 1997 . 9110174 . 10.1101/gr.7.4.353. 139146 . etal.
• Nishitani H, Lygerou Z, Nishimoto T, Nurse P . The Cdt1 protein is required to license DNA for replication in fission yeast. . Nature . 404 . 6778 . 625–8 . 2000 . 10766248 . 10.1038/35007110 . 2000Natur.404..625N . 205005540 .
• Whittaker AJ, Royzman I, Orr-Weaver TL . Drosophila double parked: a conserved, essential replication protein that colocalizes with the origin recognition complex and links DNA replication with mitosis and the down-regulation of S phase transcripts. . Genes Dev. . 14 . 14 . 1765–76 . 2000 . 10.1101/gad.14.14.1765 . 10898791 . 316778 .
• Wohlschlegel JA, Dwyer BT, Dhar SK . Inhibition of eukaryotic DNA replication by geminin binding to Cdt1. . Science . 290 . 5500 . 2309–12 . 2001 . 11125146 . 10.1126/science.290.5500.2309 . 2000Sci...290.2309W . etal.
• Yanagi K, Mizuno T, You Z, Hanaoka F . Mouse geminin inhibits not only Cdt1-MCM6 interactions but also a novel intrinsic Cdt1 DNA binding activity. . J. Biol. Chem. . 277 . 43 . 40871–80 . 2002 . 12192004 . 10.1074/jbc.M206202200 . free .
• Bermejo R, Vilaboa N, Calés C . Regulation of CDC6, geminin, and CDT1 in human cells that undergo polyploidization. . Mol. Biol. Cell . 13 . 11 . 3989–4000 . 2003 . 12429841 . 10.1091/mbc.E02-04-0217 . 133609 .
• Strausberg RL, Feingold EA, Grouse LH . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 10.1073/pnas.242603899 . 139241 . 2002PNAS...9916899M . etal. free .
• Li X, Zhao Q, Liao R . The SCF(Skp2) ubiquitin ligase complex interacts with the human replication licensing factor Cdt1 and regulates Cdt1 degradation. . J. Biol. Chem. . 278 . 33 . 30854–8 . 2003 . 12840033 . 10.1074/jbc.C300251200 . etal. free .
• Cook JG, Chasse DA, Nevins JR . The regulated association of Cdt1 with minichromosome maintenance proteins and Cdc6 in mammalian cells. . J. Biol. Chem. . 279 . 10 . 9625–33 . 2004 . 14672932 . 10.1074/jbc.M311933200 . free .
• Sugimoto N, Tatsumi Y, Tsurumi T . Cdt1 phosphorylation by cyclin A-dependent kinases negatively regulates its function without affecting geminin binding. . J. Biol. Chem. . 279 . 19 . 19691–7 . 2004 . 14993212 . 10.1074/jbc.M313175200 . etal. free .
• Liu E, Li X, Yan F . Cyclin-dependent kinases phosphorylate human Cdt1 and induce its degradation. . J. Biol. Chem. . 279 . 17 . 17283–8 . 2004 . 15004027 . 10.1074/jbc.C300549200 . etal. free .
• Ramachandran N, Hainsworth E, Bhullar B . Self-assembling protein microarrays. . Science . 305 . 5680 . 86–90 . 2004 . 15232106 . 10.1126/science.1097639 . 2004Sci...305...86R . 20936301 . etal.
• Ballabeni A, Melixetian M, Zamponi R . Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis. . EMBO J. . 23 . 15 . 3122–32 . 2005 . 15257290 . 10.1038/sj.emboj.7600314 . 514931 . etal.
• Saxena S, Yuan P, Dhar SK . A dimerized coiled-coil domain and an adjoining part of geminin interact with two sites on Cdt1 for replication inhibition. . Mol. Cell . 15 . 2 . 245–58 . 2004 . 15260975 . 10.1016/j.molcel.2004.06.045 . etal. free .
• Kulartz M, Knippers R . The replicative regulator protein geminin on chromatin in the HeLa cell cycle. . J. Biol. Chem. . 279 . 40 . 41686–94 . 2004 . 15284237 . 10.1074/jbc.M405798200 . free .
• Beausoleil SA, Jedrychowski M, Schwartz D . Large-scale characterization of HeLa cell nuclear phosphoproteins. . Proc. Natl. Acad. Sci. U.S.A. . 101 . 33 . 12130–5 . 2004 . 15302935 . 10.1073/pnas.0404720101 . 514446 . 2004PNAS..10112130B . etal. free .

Notes and References

1. Rialland M, Sola F, Santocanale C . Essential role of human CDT1 in DNA replication and chromatin licensing . J Cell Sci . 115 . Pt 7 . 1435–40 . March 2002 . 10.1242/jcs.115.7.1435 . 11896191 .
2. Nishitani H, Taraviras S, Lygerou Z, Nishimoto T . The human licensing factor for DNA replication Cdt1 accumulates in G1 and is destabilized after initiation of S-phase . J Biol Chem . 276 . 48 . 44905–11 . November 2001 . 11555648 . 10.1074/jbc.M105406200 . free .
3. Web site: Entrez Gene: CDT1 chromatin licensing and DNA replication factor 1.
4. Web site: CDT1 gene. Genetics Home Reference. en. 2018-07-19.
5. Book: Hematology : basic principles and practice. Hoffman, Ronald, 1945-, Benz, Edward J., Jr.,, Silberstein, Leslie E.,, Heslop, Helen,, Weitz, Jeffrey I.,, Anastasi, John. 2018. 9780323509398. Seventh. Philadelphia, PA. Chapter 17, 176–185. 1001961209. Hoffman. Ronald. Benz Jr.. Edward J.. Silberstein. Leslie E.. Heslop. Helen. Weitz. Jeffrey I.. Anastasi. John. Salama. Mohamed E.. Abutalib. Syed A..
6. Wohlschlegel JA, Dwyer BT, Dhar SK, Cvetic C, Walter JC, Dutta A. December 2000. Inhibition of eukaryotic DNA replication by geminin binding to Cdt1. Science. 290. 5500. 2309–12. 10.1126/science.290.5500.2309. 11125146. 2000Sci...290.2309W.
7. Hofmann JF, Beach D . cdt1 is an essential target of the Cdc10/Sct1 transcription factor: requirement for DNA replication and inhibition of mitosis . EMBO J. . 13 . 2 . 425–34 . January 1994 . 8313888 . 394824 . 10.1002/j.1460-2075.1994.tb06277.x .
8. Nakajima H, Watanabe N, Shibata F, Kitamura T, Ikeda Y, Handa M . N-terminal region of CCAAT/enhancer-binding protein epsilon is critical for cell cycle arrest, apoptosis, and functional maturation during myeloid differentiation . J. Biol. Chem. . 281 . 20 . 14494–502 . May 2006 . 16531405 . 10.1074/jbc.M600575200 . free .
9. Maiorano D, Moreau J, Méchali M . XCDT1 is required for the assembly of pre-replicative complexes in Xenopus laevis. . Nature . 404 . 622–5 . April 2000 . 10766247 . 6778 . 10.1038/35007104 . 2000Natur.404..622M . 4416138 .
10. Li X, Zhao Q, Liao R, Sun P, Wu X . The SCF(Skp2) ubiquitin ligase complex interacts with the human replication licensing factor Cdt1 and regulates Cdt1 degradation . J. Biol. Chem. . 278 . 33 . 30854–8 . 2003 . 12840033 . 10.1074/jbc.C300251200 . free .
11. Machida YJ, Dutta A . Cellular checkpoint mechanisms monitoring proper initiation of DNA replication . J. Biol. Chem. . 280 . 8 . 6253–6 . 2005 . 15591064 . 10.1074/jbc.R400037200 . free .