S-Phase progression mediates activation of a silenced gene in synthetic nuclei.
Aberrant expression of developmentally silenced genes, characteristic of tumor cells and regenerating tissue, is highly correlated with increased cell proliferation. By modeling this process in vitro in synthetic nuclei, we find that DNA replication leads to deregulation of established developmental expression patterns. Chromatin assembly in the presence of adult mouse liver nuclear extract mediates developmental stage-specific silencing of the tumor marker gene alpha-fetoprotein (AFP). Replication of silenced AFP chromatin in synthetic nuclei depletes sequence-specific transcription repressors, thereby disrupting developmentally regulated repression. Hepatoma-derived factors can target partial derepression of AFP, but full transcription activation requires DNA replication. Thus, unscheduled entry into S phase directly mediates activation of a developmentally silenced gene by (i) depleting developmental stage-specific transcription repressors and (ii) facilitating binding of transactivators.
Crowe
A J
AJ
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45267-0524, USA.
Piechan
J L
JL
Sang
L
L
Barton
M C
MC
D000818:Animals; D006528:Carcinoma, Hepatocellular; D002843:Chromatin; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase; D013698:Templates, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D014981:Xenopus; D000509:alpha-Fetoproteins / Q000235:genetics*
D002843:Chromatin; D004268:DNA-Binding Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000509:alpha-Fetoproteins