Competition between chromatin and transcription complex assembly regulates gene expression during early development.
Xenopus early development is characterized by a generalized absence of transcription, which resumes at the midblastula transition (MBT). We analyzed this regulation using a plasmid containing the c-myc promoter that is under the same developmental control when injected into fertilized eggs. We find that the repression of transcription can be relieved simply by preincubating the reporter plasmid with TATA binding protein (TBP). However, the repression of gene activity normally occurring before the MBT soon becomes dominant over this activation independent of cell cycle phases. This inactivation correlates with chromatin assembly, and titration of chromatin components not only relieves repression of TBP-dependent transcription but also permits the establishment of stable transcription during early development. Our data suggest that the large excess of histones represses gene activity during early development through a dynamic competition between chromatin assembly and transcription complex assembly.
Prioleau
M N
MN
Institut Jacques Monod, Molecular Embryology Unit, Paris, France.
Huet
J
J
Sentenac
A
A
Méchali
M
M
D000818:Animals; D002843:Chromatin / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D016195:G2 Phase / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D008845:Microinjections; D009866:Oogenesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012319:RNA Polymerase II / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics*; D014981:Xenopus / Q000196:embryology
D002843:Chromatin; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D012319:RNA Polymerase II