The Spemann organizer-expressed zinc finger gene Xegr-1 responds to the MAP kinase/Ets-SRF signal transduction pathway.
The transcriptional activity of a set of genes, which are all expressed in overlapping spatial and temporal patterns within the Spemann organizer of Xenopus embryos, can be modulated by peptide growth factors. We identify Xegr-1, a zinc finger protein-encoding gene, as a novel member of this group of genes. The spatial expression characteristics of Xegr-1 during gastrulation are most similar to those of Xbra. Making use of animal cap explants, analysis of the regulatory events that govern induction of Xegr-1 gene activity reveals that, in sharp contrast to transcriptional regulation of Xbra, activation of Ets-serum response factor (SRF) transcription factor complexes is required and sufficient for Xegr-1 gene expression. This finding provides the first indication for Ets-SRF complexes bound to serum response elements to be activated during gastrulation. MAP kinase signalling cascades can induce and sustain expression of both Xegr-1 and Xbra. Ectopic Xbra can induce Xegr-1 transcription by an indirect mechanism that appears to operate via primary activation of fibroblast growth factor secretion. These findings define a cascade of events that links Xbra activity to the signal-regulated control of Xegr-1 transcription in the context of early mesoderm induction in Xenopus laevis.
Institut für und Molekulare Zellbiologie, Universität Göttingen, Germany.
F
F
Panitz
B
B
Krain
T
T
Hollemann
A
A
Nordheim
T
T
Pieler
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D051766:Early Growth Response Protein 1; D005326:Fetal Proteins; D005346:Fibroblast Growth Factors / Q000502:physiology; D005775:Gastrula / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D017874:Immediate-Early Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010455:Peptides / Q000502:physiology; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D050783:Proto-Oncogene Proteins c-ets; D026362:Serum Response Factor; D015398:Signal Transduction / Q000235:genetics*; D020825:T-Box Domain Proteins; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000502:physiology; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology*; D016335:Zinc Fingers / Q000235:genetics*; D000098908:Brachyury Protein
D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; D005326:Fetal Proteins; D005346:Fibroblast Growth Factors; D017874:Immediate-Early Proteins; D009687:Nuclear Proteins; D010455:Peptides; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D026362:Serum Response Factor; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D000098908:Brachyury Protein; C486111:EGR1 protein, Xenopus