title: Cell cycle markers for live cell analyses.
abstract: Many cellular processes are regulated by cell cycle dependent changes in protein dynamics and localization. Studying these changes in vivo requires methods to distinguish the different cell cycle stages. Here we demonstrate the use of DNA Ligase I fused to DsRed1 as an in situ marker to identify S phase and the subsequent transition to G2 in live cells. Using this marker, we observed changes in the nuclear distribution of Dnmt1 during cell cycle progression. Based on the different nuclear distribution of DNA Ligase I and Dnmt1 in G2 and G1, we demonstrate that the combination of both proteins allows the direct discrimination of all cell cycle phases using either immunostainings or fusions with fluorescent proteins. These markers are new tools to directly study cell cycle dependent processes in both, fixed and living cells.
authors.affiliation: Max Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Hariharan P
authors.initials: HP
authors.lastname: Easwaran
authors.forename: Heinrich
authors.initials: H
authors.lastname: Leonhardt
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Cardoso
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001973:Bromodeoxyuridine / Q000494:pharmacology; D019556:COS Cells; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000737:chemistry*; D004261:DNA Replication; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes / Q000737:chemistry; D016195:G2 Phase; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D016196:S Phase; D014162:Transfection
chemical_list: D018797:Cell Cycle Proteins; D005456:Fluorescent Dyes; C000607892:LIG1 protein, human; D011993:Recombinant Fusion Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse; D011088:DNA Ligases; D000072481:DNA Ligase ATP; D001973:Bromodeoxyuridine