Replication and transcription sites are colocalized in human cells.
HeLa cells synchronized at different stages of the cell cycle were permeabilized and incubated with analogues of nucleotide triphosphates; then sites of incorporation were immunolabeled with the appropriate fluorescent probes. Confocal microscopy showed that sites of replication and transcription were not diffusely spread throughout nuclei, reflecting the distribution of euchromatin; rather, they were concentrated in 'foci' where many polymerases act together. Transcription foci aggregated as cells progressed towards the G1/S boundary; later they dispersed and became more diffuse. Replication was initiated only at transcription sites; later, when heterochromatin was replicated in enlarged foci, these remained sites of transcription. This illustrates the dynamic nature of nuclear architecture and suggests that transcription may be required for the initiation of DNA synthesis.
Hassan
A B
AB
CRC Nuclear Structure and Function Research Group, Sir William Dunn School of Pathology, University of Oxford, UK.
Errington
R J
RJ
White
N S
NS
Jackson
D A
DA
Cook
P R
PR
D001324:Autoantigens / Q000378:metabolism; D001710:Biotin / Q000031:analogs & derivatives / Q000494:pharmacology; D002453:Cell Cycle; D002467:Cell Nucleus / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication / Q000187:drug effects; D003856:Deoxyuracil Nucleotides / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D012313:RNA / Q000096:biosynthesis; D017411:Ribonucleoproteins, Small Nuclear; D014158:Transcription, Genetic / Q000187:drug effects; D055517:snRNP Core Proteins; D014544:Uridine Triphosphate / Q000031:analogs & derivatives
D001324:Autoantigens; D001710:Biotin; D004247:DNA; D003856:Deoxyuracil Nucleotides; D012313:RNA; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; C087624:biotin-16-dUTP; D014544:Uridine Triphosphate; C032549:bromodeoxyuridine triphosphate