The heat shock response in Xenopus oocytes, embryos, and somatic cells: a regulatory role for chromatin.
The heat shock response in Xenopus laevis has been reported to be developmentally regulated at the transcriptional level. We find that the heat shock response of an exogenous Xenopus hsp70 gene introduced into Xenopus oocytes, embryos, and somatic cells is dependent on the transcriptional assay conditions employed. Under conditions of efficient chromatin assembly, transcription from the Xenopus hsp70 gene promoter is repressed in oocytes and embryos, yet the promoter responds to heat shock by activating transcription. Under conditions of inefficient chromatin assembly, the Xenopus hsp70 gene is constitutively active in oocytes and somatic cells. Our results resolve previous controversy concerning the existence of a heat shock response for the hsp70 promoter in oocytes and illustrate the importance of considering chromatin assembly as a contributory factor in reconstructing the developmental control of gene expression.
Landsberger
N
N
Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
Ranjan
M
M
Almouzni
G
G
Stump
D
D
Wolffe
A P
AP
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000502:physiology* / Q000648:ultrastructure; D004247:DNA / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006358:Hot Temperature; D008845:Microinjections; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism*
D002843:Chromatin; D004277:DNA, Single-Stranded; D018840:HSP70 Heat-Shock Proteins; D004247:DNA